Keywords: Wearable assistive and augmenting devices, Rehabilitation and assistive robotics, Biomechatronic and human-centred design
Abstract: For interactive humanoids, rehabilitation robots, and orthotic and prosthetic devices, the human-robot interaction is an essential but challenging element. Compliant Series-Elastic Actuators (SEAs) are ideal to power such devices due to their low impedance and smoothness of generated forces. In this paper we present the ServoSEA, which is a miniature Series-Elastic Actuator (SEA) based on cheap RC servos, and which is useful for actuation of orthotic, prosthetic or robotic hands. RC servos are complete packages that come with rotary motor and sensor and have an integrated control board to control the output angle. In the ServoSEA, a small rotational spring is attached to the output shaft and the internal rotary sensor is relocated to measure the spring deflection. These small modifications immediately make the integrated control board behave as a series-elastic torque controller. Here we present several design alternatives and report on the performance of our implementation that will be used in the active SCRIPT wrist and hand orthosis. The performance measurements showed that feedforward control of the example implementation of the ServoSEA results in acceptable, though not perfect, force tracking behavior. It is clear that although the ServoSEA concept is universal, final performance strongly depends on the quality of the original RC servo.

Keywords: Prosthetic devices, Rehabilitation and assistive robotics, Human-machine interaction
Abstract: This paper presents an algorithm to process the electromyography signal (EMG). It requires low computational power which allows it to be implemented in embedded, low cost platforms. The proposed algorithm uses the Short-Time Fourier Transform (STFT) and the feature extraction methods, namely, modified mean frequency, and the first spectral moment (SM1). This algorithms is able to identify four different movements of one upper limb, allowing to control a robotic assistance tool with four degrees of freedom. Thanks to the properties of this algorithm, rural populations can have access to this type of technologies.

Keywords: Prosthetic devices
Abstract: Dynamically monitoring muscle contraction is an important task in sports training and rehabilitation programs. Internal muscles monitoring are specially challenging because they cannot be accessed by palpation or surface EMG. It is well known that blood flow through skeletal muscle can increase 15- to 25-fold during extreme exercise compared to its rest state. Additionally, at rest, some muscle capillaries have little or no blood flowing, but during strenuous exercise, all the capillaries open. With regard to electrical properties, blood resistivity is about half of muscle resistivity. Thus, global muscle resistivity have a tendency to change when it goes from rest to activity state. Recent results suggest that resistivity changes are related to contraction rate. Bearing that in mind, Electrical Impedance Tomography turns out to be an interesting signal to monitor muscle contraction by sensing resistivity changes related to muscle activity. If low intensity current is injected and electric potentials are measured through electrodes attached on skin, resistivity maps can be obtained using this data to solve an ill-posed inverse problem. In this work the electrical impedance was measured while a muscle was under repetitive contractions. Significant changes of electrical impedance were found in the frequency of contractions.

Keywords: Prosthetic devices, Wearable assistive and augmenting devices, Biomechatronic and human-centred design
Abstract: Development of active systems in the field of prostheses and orthotics is currently one of the main topics in medical rehab research. As in this field different researcher from different disciplines, not only from technical areas like informatics, mechanical engineering and electrical engineering, but also from medical and biological research do have to work together, there is a strong need for an integrative development procedure. In this paper a systematic and methodical approach for the development of active systems in the field of Prosthetics and Orthotics is presented. Two examples of active powered devices in this field are shown. One is an active powered knee prosthesis. The other one is an active powered arm orthosis. The presented procedure starts with the definition of the boundary conditions, which are derived from the application, and ends with a graphical description of the important parameters for the power train in powered P&O devices.

Keywords: Human-machine interaction
Abstract: Sleep disorders affect about one third of the general population. Rocking movements may help to shorten sleep onset latency and enhance sleep quality. However, from a scientific point of view, the relation between vestibular stimulation and sleep remains unclear. This paper presents a novel device to investigate the influence of vestibular stimulation on sleeping human subjects. The developed device includes two actuated bed platforms allowing to provide adjustable rocking motion along five different movement axes: three translations along the longitudinal, lateral, and vertical body axes, and two swing-like rotations along longitudinal and lateral direction. The robotic platforms have been designed in order to fulfil the special requirements of sleep research. Rocking trajectories with linear velocity below 15 cm/s ensure smooth, confortable, and quiet conditions (L_eq<40 dBA) for all the five axes. The presented approach will allow to systematically investigate the influence of different kinds of rocking movement on human sleep.

Keywords: Human-machine interaction, Rehabilitation and assistive robotics
Abstract: A proper seating is important as an aid for cerebral palsy patients, and has good influence on patients’ physical conditions and mentalities. Deformity of spine causes gaps between their backs and backrests of wheel chairs. Generally, urethane cushions are used to fill up the gaps. However, this method cannot handle their dynamic motion that will happen in daily life. In the previous study, we developed the first prototype of the intelligent seating system (i-Seating 1) by using a conventional adjustable-belt type seating and some air bags on the belts. We could control the posture and pressure of users, but there is a severe limitation for real situations. In this paper, we propose to use an adjustable sheet mechanism for the wheelchair seating. The adjustable sheet mechanism is very simple and a combination of a main sheet and adjustment belts. We installed this mechanism in the conventional adjustable-belt type seating. For convenience of the adjustment, we also developed a back-shape measurement system and proposed an adjustment method on the basis of the measurement results. Finally, a validation test was conducted and evaluated. The experimental result indicated that the adjustable sheet fit to the complex back shape and controlled a good posture and even pressure for a dummy deformed backbone.

Keywords: Human-machine interaction, Rehabilitation and assistive robotics, Wearable assistive and augmenting devices
Abstract: The development of a glove-based sensor using flexible optical fiber microbending transducers for applications in biomechatronics is reported. The devices are attached onto the dorsal surface of monitored joint, with sensibility to detect of variations of ~4° in angular displacements. In addition, the sensor system was evaluated for the real-time detection of hand movements, as well as for the assessment of grasping patterns during the manipulation of cylindrical objects. The preliminary experiments indicated that sensor could be suitable for practical applications in robot-assisted rehabilitation and diagnosis of impaired subjects.

Keywords: Rehabilitation and assistive robotics, Locomotion and manipulation in robots and biological systems, Human-machine interaction
Abstract: A mechatronic system for neurorehabilitation of motion system of the human lower limbs is presented. Moreover, the structure of the complex and its components – feet training device with acupressure effect on feet, half-bed standing frame (verticalizer), lower limbs exoskeleton to operate them in case of loss of mobility or for active workouts are presented. The complex is designed to help patients who have lost the mobility of the lower limbs, or to work with athletes or astronauts on different stages of rehabilitation.

Keywords: Micro/nano technologies in medicine and biology, Technology for assisted surgery and diagnosis, Biological systems modeling
Abstract: An experimental research of the drug pyrazinamide is analyzed and tested with potentiometric method. By understanding the biomechatronic system, consisted of a mechanism of action of the drug Pyrazinamide in a biological system, and an electrical signals, voltametric measures, a method to detect resistance to this specific drug is developed and tested firstly in vitro, then in cultures and finally in decontaminated sputum.

Keywords: Biologically-inspired systems, Locomotion and manipulation in robots and biological systems, Prosthetic devices
Abstract: For almost 20 years, dielectric elastomer actuators (DEAs) have been the subject of intense research in material science. A large number of publications describe artificial muscles based on DEAs as a promising alternative for an energy efficient, lightweight and flexible actuation architecture. DEAs could improve and extend the capabilities of robotic and prosthetic devices in terms of their dynamical performance and their eligibility for energy autarkic operation. However,up to now DEAs are not available on a large scale with reproducible characteristics nor are they yet usable on a system integration level. In this paper we present recent findings of our ongoing five-year project to qualify DEAs as feasible artificial muscles for usage in compliant robot kinematics and soft prosthetic devices. The focus of this contribution lies on a new automated production process using Aerosol Jet Printing for stacked DEAs with very thin layers for reduced driving voltages and improved mechanical characteristics resulting from the additive manufacturing. Secondly, a new set of lightweight power electronics based on pulse width modulation (PWM) is presented which aims at the improvement of the overall specific power of DEA driven kinematic systems.

Keywords: Rehabilitation and assistive robotics, Prosthetic devices
Abstract: The goal of this paper is to investigate the temporal-spectral decomposition content during a maximal electrically evoked contraction (MEEC) in two spinal cord injured participants using triaxial mechanomyography (MMG). Two male spinal cord injured volunteers performed the tests both injured at T7 neurologic level. The triaxial MMG signal of rectus femoris muscle was processed with Cauchy wavelet transform adjusted to third-order 5-50 Hz bandpass Butterworth filter. A custom electrical stimulator voltage-controlled was configured: pulse frequency set to 1 kHz (20% duty cycle) and burst (modulating) frequency set to 70 Hz (20% active period). The MEEC force was performed by increasing the electrical stimulating magnitude (~3 V/s to avoid motoneuron adaptation/habituation) until the force started to level off. We conclude that the peak energy of MMG signal frequency did not occur simultaneously with the maximal electrically evoked contraction to rectus femoris muscle. Moreover, the vibration vector of muscle, expressed in three axes (X, Y and Z), presented different fired frequencies, mainly between X (transverse) and Z (perpendicular) axis, where the frequencies fired by Z axis were greater.

Keywords: Neuro-robotics, Biologically-inspired systems, Neuroengineering
Abstract: The cerebellum plays a crucial role in motor learning and it acts as a predictive controller. A biological inspired cerebellar model with distributed plasticity has been embedded into a real-time controller of a neurorobot. A cerebellum-driven task has been designed: the Vestibulo-Ocular Reflex (VOR), which produces eye movements stabilizing images on the retina during head movement. The cerebellar controller drives eye compensation, by providing joint torque based on network output activity. We compared a cerebellar controller with only the cortical plasticity and a cerebellar controller with also the plasticity mechanisms at deep nuclei, in VOR multiple sessions. The results were interpreted using a two state multi-rate model integrating two learning processes with different sensitivities to error and different retention strengths. The cerebellar model showed effective learning along task repetitions, allowing a fine timing and gain adaptation based on the head stimulus. The multisite plasticity proved superior to single-site plasticity in generating human-like VOR during acquisition, extinction and consolidation.

Keywords: Human-machine interaction, Rehabilitation and assistive robotics
Abstract: This work deals with the development of a controller for a robotic platform conceived as a rehabilitation device for the human upper limb. The mechanical system is a three-degree-of-freedom parallel mechanism which is coupled to the actuators, three DC-motors and the drives that provides the desired control signals (position, velocity and current). Regarding the control system, two techniques are utilized: the computed torque control for the motion control and the impedance control for force control. Simulations are performed in MatLab software in order to evaluate the interaction with a user.

Keywords: Locomotion and manipulation in robots and biological systems, Biologically-inspired systems
Abstract: In this paper, we investigated the dynamic characteristics in the gait of a quadruped robot, which is controlled by an oscillator network constructed based on the physiological concept of central pattern generators and the physiological evidence of phase resetting. From the observation in humans, two parameter cusp catastrophe is suggested to be embedded in the walk–run transition with the locomotion speed and additional load as control parameters. In our previous work, simulation studies revealed that a quadruped robot model produces the walking and trotting gaits depending on the locomotion speed and it shows the cusp bifurcation due to additional weights similar to humans through dynamic interactions among the robot's mechanical system, the oscillator network system, and the environment. The aim of the present study is to verify such dynamic characteristics in the cusp catastrophe of the gait transition in the locomotion of our quadruped robot model in the real world by using a quadruped robot.

Keywords: Micro/nano technologies in medicine and biology, Locomotion and manipulation in robots and biological systems, Surgical navigation and robotics
Abstract: In this paper, we proposed an intravascular therapeutic microrobot using an electromagnetic actuation (EMA) system with bi-plane X-ray imaging device. The proposed EMA system consists of Helmholtz-Maxwell coils, uniform-gradient saddle coils. The Helmholtz-Maxwell coils are located along y-axis, and uniform-gradient saddle coils are located perpendicular to y-axis. In order to align the microrobot along a desired angle in 2D (dimensional) plane, it is necessary to control of the currents on Helmholtz coil and uniform saddle coil. For a forward and backward direction movement of the microrobot, we precisely control the currents of Maxwell coil and gradient saddle coil. Because the saddle coils can be rotated around the y-axis, the effective actuation plane of the microrobot can be also rotated, and the microrobot can move in 3D space. In addition, for the position recognition of the microrobot in a blood vessel, we adopted a bi-plane X-ray fluoroscopy. If the saddle coils are rotated around the y-axis, an open area is changed. Therefore, the saddle coils and bi-plane X-ray fluoroscopy must be rotated simultaneously. To confirm the feasibility of 3D locomotion of the microrobot, we executed a locomotion test of the microrobot in the blood vessel phantom, where the blood vessel phantom was fabricated by the rendering data from computed tomography (CT) images of the iliac artery and 3D printer.

Keywords: Biologically-inspired systems, Locomotion and manipulation in robots and biological systems
Abstract: The multiple robot coordination strategies have several advantages when compared to strategies based on a single robot, in terms of flexibility, gain of information and reduction of map building time. In this paper, a local pheromone map integration method is proposed based on the inter-robot observations, considering a method for the environment exploration named the Inverse Ant System-Based Surveillance System strategy (IAS-SS). Simulation results show that the map integration method is efficient, the trials are performed considering a variable number of robots in an indoor environment. Results obtained from several experiments confirm that the integration process is effective and suitable to execute the control of the access to pheromones in a virtual way.

Keywords: Biologically-inspired systems, Micro/nano technologies in medicine and biology, Locomotion and manipulation in robots and biological systems
Abstract: For the actuation of a swimming microrobot, various types of electromagnetic actuation (EMA) systems were proposed. Compared with a conventional actuation system using an electric motor or shape memory alloy (SMA), EMA system has many advantages for a wireless actuation of a microrobot. This paper introduces a biomimetic swimming tadpole microrobot. The developed microrobot could be driven by an external uniform magnet field using 3-pairs of Helmholtz coils. The swimming microrobot consists of a buoyant body, NdFeB magnets, and silicone fin. Especially, the tadpole swimming microrobot has a single silicone fin which is directly linked to the NdFeB magnet. The external alternating magnetic field from 3- pairs of Helmholtz coils could generate the propulsion and steering force of the tadpole microrobot in 3-dimensional (D) space. The proposed swimming tadpole microrobot can be used in medical areas such as a capsule endoscope and drug delivery system.

Keywords: Biological systems modeling, Wearable assistive and augmenting devices, Rehabilitation and assistive robotics
Abstract: This paper presents a novel estimation method for extracting the activation rate of the human leg muscles using the recursive least squqres algorithm. It is shown that the output force of each leg muscle group can be simply estimated from the reconstructed real measurement data. The estimation result turned out to be fairly comparable to those from electromyography, yet much simpler and faster. Considering the importance of the knowledge regarding the activation and deterioration state of each leg muscle group for rehabilitation, the proposed method is expected to contribute to the progress in the fields of biomechanics, by providing a simple, accurate, and fast estimation data to the developers, which will lead to the controller design of adaptive type walking assist devices.

Keywords: Micro/nano technologies in medicine and biology, Biologically-inspired systems, Locomotion and manipulation in robots and biological systems
Abstract: Microrobots are useful for application in various fields. However, they have limitations with respect to their actuators and motilities. In this study, we fabricated the two types of flagellated bacteria-actuated microrobots using the flagellated bacteria Serratia marcescens and Salmonella typhimurium that could be utilized as microactuators. First, we fabricated the Serratia marcescens-actuated microrobot, where we adopted the selective bacteria adhering on the surface of SU-8 microcubes through the selective coating with bovine serum albumin. Many number of Serratia marcescens attached on bovine serum albumin-uncoated side of SU-8 microcubes. The average velocity of the selective Serratia marcescens-attached SU-8 microcubes was increased more than two times from SU-8 microcubes with a nominal Serratia marcescens attachments. Second, we fabricated the Salmonella typhimurium-actuated microrobots that have a selective bacteria patterning on the surface of polystyrene microbeads using bovine serum albumin. Similarly, the average velocity of the selective Salmonella typhimurium patterned polystyrene microbeads was 5 folds faster than that of the polystyrene microbeads where the bacteria were attached on the whole surface of the microbeads. Consequently, the experimental results mean that the flagellated bacteria could be utilized as microactuators for microrobots and the selective patterning of the bacteria could enhance the velocity of the bacteria-actuated microrobots.

Keywords: Micro/nano technologies in medicine and biology, Locomotion and manipulation in robots and biological systems, Biologically-inspired systems
Abstract: This paper proposed an analysis program which can filter the moving phase of Peritrichous bacteria and analyze the rotational motion of a bacteria-based nanorobot (bacteriobot) with a spherical body. Using this program, the chemotactic steering of Salmonella typhimurium was quantitatively analyzed. The program used the bacterial running phase only to obtain an exact direction of the bacteria. As another implementation of this program, the motility of a bacteriobot which consists of an alginate microbead and flagellated bacteria has been analyzed. It showed a slow translational velocity and a relatively high angular velocity of a bacteriobot with a single attached bacterium. These results mean the propulsive force of a single bacterium gives some torque to the microbead. Therefore, the bacteriobot needs an additional external sources for an efficient translational motility such as chemical gradients, light intensity and magnetic fields.

Keywords: Locomotion and manipulation in robots and biological systems, Biomechatronic and human-centred design, Rehabilitation and assistive robotics
Abstract: Understanding how the postural control system is impaired with aging can help identify elderly at risk of falling. In order to study the postural control, center of pressure (COP) behavior can be analyzed. The objective of this study was to evaluate the capacity of Detrended Fluctuation Analysis (DFA) to discriminate the postural control of elderly in horizontal and inclined (14 degrees) surfaces, with and without visual input, comparing the results with that obtained with the classical variables, such as mean velocity and total COP displacement. Results with classical variables revealed significant differences in all comparisons executed, but DFA was not able to discriminate the differences between conditions. It is suggested further studies to verify the efficiency of DFA in physiologically different groups, like subjects with some pathology that affects the balance or the ones wearing a robotic prosthesis from healthy subjects, in which it seems to have a greater sensitivity.

Keywords: Biologically-inspired systems, Locomotion and manipulation in robots and biological systems
Abstract: Humanoid fall avoidance is the ability of a robot to avoid falling when pushed. The decision surface is a region on the phase diagram delimiting the states beyond which the robot cannot recover from a disturbance. The disadvantage of the decision surface is that it is limited to perturbations in the sagittal and coronal planes. This paper deals with the generalisation of the decision surface to a decision volume, used for the prediction of limiting states for recovery from disturbances in any orientation. A second contribution is the extension of the ankle strategy for humanoid fall avoidance to disturbances in random directions. The model used is a 3D Linear Inverted Pendulum Model (LIPM). Both, ankle strategy and decision volume are tested on the Webots simulator then implemented on a real humanoid robot.

Keywords: Locomotion and manipulation in robots and biological systems, Biologically-inspired systems, Biological systems modeling
Abstract: This paper presents a study of the center of pressure (COP behavior during anticipatory postural adjustments phase (APA of gait initiation in different conditions which are commonly required in daily activities. Twelve young subjects enrolled in this study and performed gait initiation in horizontal and upward and downward inclined surfaces. Significant differences were found only in the medial-lateral (ML) displacement and velocity of COP on both inclined surfaces. These results suggest a smaller transfer of the center of mass to the support foot in this phase on inclined surfaces. This should be taken in account in the design of bipedal robots once the ML COP control is an important aspect of gait initiation.

Attachments: Video
Keywords: Biomechatronic and human-centred design, Biological systems modeling, Biologically-inspired systems
Abstract: This paper presents a control approach to express muscle-tendon complex in a musculoskeletal humanoid robot. Kenshiro is a full body tendon driven humanoid robot and is designed from the data of average 14 year old Japanese boy. By winding wires by motors we can express the contraction of muscles, and in this paper we introduce novel actuation system realized by integrating “Tension controlled Muscle(TCM)” and “Non-linear Spring Ligament(NSL)”. Combination of active and passive compliance control is explained in this paper to realize the behavior of muscle-tendon complex(MTC). This enables flexible behavior of Kenshiro, and mimic joint trajectory of human when external force is applied. At the same time the tension data of the load cells can be regarded as muscle tension. In this way it becomes possible to use musculoskeletal humanoid robots for measuring biological data quantitatively. Application of Kenshiro as actively movable car crash simulation mannequin is illustrated by an example as a future work.

Keywords: Locomotion and manipulation in robots and biological systems, Biologically-inspired systems
Abstract: In this study, we conducted computer simulation of splitbelt treadmill walking by the hindlimbs of a rat based on a neuromusculoskeletal model. We developed the skeletal model based on anatomical data and constructed the nervous system model for locomotion based on the physiological findings of muscle synergy, central pattern generator, and sensory regulation by phase resetting. Our simulation results show that even in asymmetric environment due to the speed discrepancy between the left and right belts of a splitbelt treadmill, the rat model produced stable walking. The sensory regulation model contributed to generation of adaptive splitbelt treadmill walking while inducing the modulation of locomotion parameters, such as relative phase between the legs and duty factors, as observed in splitbelt treadmill walking of humans and animals. This helps understanding of the adaptation mechanism in locomotion through dynamic interactions among the nervous system, the musculoskeletal system, and the environment.

Attachments: Video
Keywords: Biologically-inspired systems, Biomechatronic and human-centred design, Locomotion and manipulation in robots and biological systems
Abstract: Muscle has a remarkable ability to continue functioning despite sustaining damage. This paper presents an actuation platform that, like muscle, is composed of discretely activated motor units with an integrated compliant coupling. This modular structure endows an actuator made up of these units with the same damage-resistant properties, as well as the ability to ``grow'' (by adding units) rather than replacing the actuator to cope with changing load requirements. Controlling an actuator composed of on-off motor units may seem to entail a reduction in performance and an increase in complexity, but due to the inherent compliance and fast-moving active elements, the reduction in dynamic performance is expected to be slight. This actuation platform presents a means by which algorithms for control of muscle-like systems can be studied and evaluated, and where further ways to exploit discretization and redundancy in muscle-like control can be discovered.

Several performance metrics particular to muscle-like ac- tuators are introduced and calculated for a sample prototype of this technology. The prototype has a blocked force of 2.51 N, a strain rate of 21.1 %, and has an input density of 5.46 103 inputs/m2. It consumes 18 W of power during a full isometric contraction. The actuator unit is 41.0 mm3 in size. Experiments are conducted to measure the force during isometric contractions as it varies with activation.

Keywords: Biologically-inspired systems, Locomotion and manipulation in robots and biological systems, Rehabilitation and assistive robotics
Abstract: Living organisms are characterized by their smooth adaptability to environmental changes and their robustness against morphological modifications. To investigate the computational mechanisms behind such learning scheme, we proposed tacit learning as a novel learning method. In tacit learning, there are no clear distinctions between learning and motor control: learning is a simple accumulation process embedded in the controller. In previous work, tacit learning was applied with success to bipedal locomotion of a 36 DoF humanoid robot. In this paper, we generalize the structure of the controller such as applying adaptive integration to a wider range of systems and behaviors. This is achieved by applying the principle of tacit learning in a hierarchical fashion, in which the value of a virtual periodic dynamic variable is tuned for continuous adaptation. This resulting PD-PI (proportional-derivative periodic-integration) controller preserves the advantages of tacit learning that the controllers do not include any prior knowledge of the system in which they are embedded. It also shares with biological systems the property that control and adaptation progress without explicit distinction between them.

Keywords: Biologically-inspired systems, Wearable assistive and augmenting devices, Locomotion and manipulation in robots and biological systems
Abstract: We present a novel sampling and processing method for detecting gait events from an insole pressure sensor. Inspired by how tactile data is processed in the brain, we propose the use of timing, instead of intensity, as our event detection feature. By sacrificing the need for accurate intensity measurements, it is possible to achieve superior temporal resolution, which is arguably more important given the need for timely feedback. In this paper, we demonstrate temporally accurate gait-event detection of 1.2/7ms (mean/standard deviation) for heel-strike and 0.2/14ms for toe-off events compared to the reference system, and a success rate of above 97% in most trials, using only 1 bit of pressure information per channel. Our method thus has the potential to achieve much lower computational complexity and bandwidth, both of which are key to low-cost, portable solutions for prosthetics, exoskeletons or long-term gait monitoring applications.

Attachments: Video
Keywords: Biologically-inspired systems, Biological systems modeling, Locomotion and manipulation in robots and biological systems
Abstract: Elastic properties of muscles and tendons are assumed to play a central role for the energy efficiency and robustness of locomotion in biological systems. Yet, the way in which the nervous system controls highly nonlinear body dynamics to produce stable periodic motions is far from being well understood. On the basis of a simple but very effective control law, which we developed and verified for variable impedance robots, we propose a controller model, which might be a very plausible hypothesis also for biological systems. The original robot controller has a bang-bang action triggered by the generalized force acting along a coordinate corresponding to the principal oscillation mode of the system. This coordinate is computed in a model-free, adaptive manner. It turns out that the control law can be easily realized with a neural network, whose weights are adapted according to the Hebbian learning rule. If this hypothesis is confirmed, cyclic body motions can be very easily and robustly implemented, with a surprisingly small number of neurons.

Keywords: Biologically-inspired systems
Abstract: A flapping-wing micro air vehicle mimicking the fruit flies strategy of biasing their wing hinges to indirectly modulate its wings’ angle of attack to create yaw torques was built. This concept could also generate roll torques by oscillating the wing hinge at the flapping frequency of the vehicle. The roll, yaw and pitch torque generation capability was characterized using a custom single axis torque sensor. The vehicle could produce 0.8μNm of roll torque, 1μNm of yaw torque and 0.8μNm of pitch torque which enables it to have turning performances comparable to fruit flies.

Attachments: Video
Keywords: Locomotion and manipulation in robots and biological systems, Rehabilitation and assistive robotics, Biomechatronic and human-centred design
Abstract: This paper presents the Achilles exoskeleton, an autonomous ankle exoskeleton that can generate 52% of the positive plantarflexion power around the ankle of a 80 kg individual with only 1.5 kg of mass added around the ankle joint. The mass of the exoskeleton is lower and the power density is higher than that of existing autonomous exoskeletons. This high power density was achieved by designing a series elastic actuator that consists of an electric motor and ball-screw gear with a carbon fiber reinforced leaf-spring as lever-arm. A dynamic model that includes the motor and gear properties, spring stiffness, and exoskeleton geometry was used to optimize the design parameters for positive power injection. Doing this for multiple combinations of preselected motors and gears and comparing their support to weight ratio, revealed the best drive combination. The performance of the realized exoskeleton was assessed in several tests. The actuator can track the optimized actuator stroke trajectory with a following error that has a RMS of 2.3 mm, it can track force reference signals with amplitudes of 1 N to 100 N with a bandwidth between 8.1 Hz and 20.6 Hz, and it outputs a maximum mechanical power of 80.2 W. These results show that the device is suitable for fulfilling its purpose: reducing the metabolic cost of walking with an autonomous device.

Keywords: Locomotion and manipulation in robots and biological systems
Abstract: The Segmented Spring-Loaded Inverted Pendu- lum model is analysed, and it is shown that it exhibits walking gait. We propose a control architecture that exploits control of the knee stiffness to provide robustness of the system with respect to changes in gait. This controller is extended for a realistic bipedal robot model that uses variable stiffness actuators to control the knee stiffness. The variable knee stiffness is then used to stabilise the system into a walking gait and to inject energy losses generated by friction and foot impacts.

Keywords: Locomotion and manipulation in robots and biological systems
Abstract: The Spring-Loaded Inverted Pendulum (SLIP) model has been shown to exhibit many properties of human walking, and therefore has been the starting point for studies on robust, energy-efficient walking for robots. In this paper, the problem of gait variation during walking on the SLIP model is addressed by controlling the leg stiffness and the angle-of-attack in order to switch between gaits and thus regulate walking speeds. We show that it is possible to uniquely describe SLIP limit cycle gaits in fully normalised form. Using that description, we propose both an instantaneous switching method and an interpolation method with an optimisation step to switch between limit cycle SLIP gaits. Using simulations, we show that it is then possible to transition between them, after which the system converges back to zero-input limit cycle walking.

Keywords: Locomotion and manipulation in robots and biological systems
Abstract: Passive Dynamic Walking overcomes elegantly several drawbacks of the high gain position control approach to generate bipedal gait of robots. In this scenario the Limit Cycle Walking concept leads to the generation of high energetically efficient gait. The goal of this paper is to demonstrate how the implementation of an ex-novo controller - based on switched reference partial feedback linearization - can increase the basin of attraction of a Limit Walking Cycle. The simulation has been performed on a compass gait model. The controller simulation and the mechanical model description have been defined through a range of initial conditions for the state variables. The results demonstrated that the controller was able to increase the basin of attraction of the compass gait model with respect to the passive system. The novel controller has a low computational load, which makes it a perfect candidate for the implementation on real prototypes.

Keywords: Rehabilitation and assistive robotics, Wearable assistive and augmenting devices, Human-machine interaction
Abstract: This paper describes the design and development of an exoskeleton that can deliver assistance-as-needed to patients or elderly with muscle weakness. Since the proof-of-concept is a first step towards the development of a final commercial prototype, the design had to be adaptable for patients with different heights, be comfortable for the patients, safe in use, energy-efficient and affordable in production. For this reason a modular system was built, using the same compliant actuator system in all joints. This paper describes the global design decisions made and the construction of the actual prototype.

Attachments: Video
Keywords: Locomotion and manipulation in robots and biological systems, Biomechatronic and human-centred design, Biologically-inspired systems
Abstract: This paper introduces ModGrasp, an open-source virtual and physical rapid-prototyping framework that allows for the design, simulation and control of low-cost sensorised modular hands. By combining the rapid-prototyping approach with the modular concept, different manipulator configurations can be modelled. A real-time one-to-one correspondence between virtual and physical prototypes is established. Different control algorithms can be implemented for the models.

By using a low-cost sensing approach, functions for torque sensing at the joint level, sensitive collision detection and joint compliant control are possible. A 3-D visualization environment provides the user with an intuitive visual feedback.

As a case study, a three-fingered modular manipulator is presented. Related simulations are carried out to validate efficiency and flexibility of the proposed rapid-prototyping framework.

Keywords: Locomotion and manipulation in robots and biological systems
Abstract: In this paper development, implementation and experimental validation of a grasp synthesis algorithm for an anthropomorphic robotic arm-hand system in a low dimensional posture subspace is proposed. The algorithm has been developed on the basis of the analysis of human hand postural synergies. Drawing inspiration from neuroscientific studies, a database of grasps has been created through the observation and the analysis of the human finger posture during reaching and grasping tasks of several objects. The optimal hand configuration and wrist pose have been determined by applying an optimization procedure grounded on a stochastic method. The grasp synthesis algorithm has been validated in simulation and on a real arm-hand robotic platform consisting of the KUKA LWR 4+ robot arm and the DLR-HIT Hand II. The experimental results have validated the hypothesis made during algorithm implementation and have shown that the arm-hand robotic platform is able to perform the hand preshaping configurations predicted by the grasp synthesis algorithm.

Keywords: Biological systems modeling, Locomotion and manipulation in robots and biological systems, Rehabilitation and assistive robotics
Abstract: In this study, we propose to explore inverse optimization process to better understand human arm motion in industrial screwing task. The process combines several criteria to minimize such as energy expenditure or trajectory smoothness leading to the optimal trajectory of a typical screwing task, often performed by workers. Estimated joint trajectories are similar with the measured ones, with a mean square error of 4 degrees. The resulting cost-function is mainly composed of energy expenditure and geodesic criteria. Results show the relevance of using composite cost functions in human motion planning. This study has been conducted to assist workers by using cobots in painful task in PSA Peugeot Citroen factories to improve ergonomics of manual workstations.

Keywords: Rehabilitation and assistive robotics, Human-machine interaction, Locomotion and manipulation in robots and biological systems
Abstract: According to the World Report on Disability, currently 93 million children experience some kind of moderate or severe disability. Several systems including motion capture, serious games, exoskeletons and robotics have been researched and developed for assisting them on recovering basic functionality and daily activities, thus, improving mobility and providing a better quality of life. The popularization of these tools is a challenging task due to the required technical knowledge and the high acquisition costs, yet, the field of didactic robots is growing as an alternative that can be used in education, research, entertainment and other scenarios. This project proposes the development of the emph{Pomodoro} mobile robot as a device for encouraging hand motion exercise through flexion/extension and ulnar/radial deviation movements, for teleoperating the system in users experiencing reduced hand mobility. The system is composed of a low cost non-holonomic robot controlled with an embedded smartphone for on-site interactions through speech, image recognition and touch controls, along with a complimentary hand motion tracking subsystem for teleoperating the system using both real and virtual system, while recording position and orientation data for further assessment.

Keywords: Biomechatronic and human-centred design, Human-machine interaction, Biologically-inspired systems
Abstract: Thumb workspace analysis on touch-sensitive screen is used to assist designers in laying control buttons out on screen devices which are thought to be one- handed operated, eg mobile phones. Using inertial motion tracking system, kinematic variables as position and orientation for thumb link are obtained. Based on Euler angles, the motion angle for each thumb joint relative to its comfort position is lculated for a determined number of touch points on the screen. Additionally, touch points are associated to distal phalange link inclination which correspond to a tip thumb contact area that affect the touch precision. The collected data is used to calculate discomfort index and the contact area over the total thumb workspace and map them on the screen. Through calculations it is possible to conclude that some movements are performed easily (comforting) and/or precisely than others, eg finger vertical sliding is easier than horizontal one. Finally, in order to improve user comfort and precision, on the screen area, where control buttons should be shown. This analysis is applied, as a practical example, on a personal magazine smartphone application, in order to suggest a suitable design for the control buttons.

Keywords: Biologically-inspired systems, Biological systems modeling
Abstract: The unstructured scenario, the extraction of significant features, imprecision of sensors along with the impossibility of using GPS signals are some of the challenges encountered in underwater environments. Given this adverse context, the Simultaneous Localization and Mapping techniques (SLAM) attempt to localize the robot in an efficient way in an unknown underwater environment while at the same time, generate a representative model of the environment. In this paper, we focus on key topics related to SLAM applications in underwater environments. Moreover, a review of major studies in the literature and proposed solutions for address the problem are presented. Given the limitations of probabilistic approaches, a new alternative based on a bio-inspired model is highlighted.

Keywords: Locomotion and manipulation in robots and biological systems
Abstract: Swarm robotics requires the development of new strategies and algorithms integration, which allow improving the design and applications for harvesting or collecting resources. This paper shows how to program and design Finite State Machines (FSM) bio-inspired algorithms for seeker and resource gathering Pherobots systems, like Anthill Known Location (AKL) aggressiveness and sense of panic. FSM designing allows using control architecture for behaviour-based agents and measuring the change in system performance. Simulations demonstrate the capability of the algorithms under different environments and scenarios.

Keywords: Locomotion and manipulation in robots and biological systems, Biologically-inspired systems, Rehabilitation and assistive robotics
Abstract: This paper considers guidance-based motion control of planar snake robots using a dynamic feedback control law. We first present the Euler-Lagrange equations of motion of the robot. Subsequently, we introduce a dynamic feedback control law for the joints of the robot to track a desired gait pattern. This tracking control law depends on the time evolution of the state variables of a dynamic compensator which is used for controlling the orientation of the robot. In particular, we employ the dynamic compensator to practically stabilize a reference head angle defined by a Line-of-Sight path following guidance law. Using an input-output stability analysis, we show the uniform boundedness of the solutions of the controlled system. Furthermore, we use a perturbation analysis to show that the orientation error is ultimately bounded by an arbitrarily small bound. Simulation results are presented to validate the theoretical results.

Keywords: Biologically-inspired systems, Locomotion and manipulation in robots and biological systems, Biological systems modeling
Abstract: Inspired by the aerial prowess of flying insects, we demonstrate that their robotic counterpart, an insect-scale flapping-wing robot, can mimic an aggressive maneuver seen in natural fliers—landing on a vertical wall. Such acrobatic movement differs from simple lateral maneuvers or hover, and therefore requires additional considerations in the control strategy. Magnetic force was chosen to enable attachment to the vertical surface due to its favorable scalability and simplicity. We show that by learning from previous failed attempts, the robotic fly could successfully perch on a magnetic wall after 8 iterations.

Keywords: Locomotion and manipulation in robots and biological systems, Rehabilitation and assistive robotics, Biological systems modeling
Abstract: Our goal is to introduce a more appropriate method of generalising walking gaits across different subjects and behaviours. Walking gaits are a result of complex factors that include variations resulting from embodiments and tasks, making techniques that use average template frameworks suboptimal for systematic analysis. The proposed work aims to devise methodologies for being able to represent gaits and gait transitions such that optimal policies may be recovered. The problem is formalised using a walking phase model, and the nullspace learning method is used to generalise a consistent policy. This policy can serve as reference guideline to quantify and identify pathological gaits. We have demonstrated robustness of our method with motion-capture data with induced gait abnormality. Future work will extend this to kinetic features and higher dimensional features.

Keywords: Prosthetic devices, Human-machine interaction, Biomechatronic and human-centred design
Abstract: In knee prosthetics and orthotics, there is the need to have a change in stiffness within the gait cycle. Doing this using a locking mechanism requires locking high forces using a small amount of energy. This paper presents a novel compact and light-weight locking mechanism which combines a ratchet-and-pawl and a singular position locking mechanism. It is used as a lock in a passive knee prosthesis and allows a change in compliance of the joint. The mechanism is transparent during the swing phase, allowing the joint to flex, and during the weight acceptance phase it provides the same stiffness as a natural knee joint. It is explained that this high stiffness characteristic can be approximated by a linear spring put in parallel with the knee joint. The mechanism uses a small servo motor to unlock the ratchet, other than this the operation is fully passive. The prosthesis has been tested during walking tests with amputee test subjects. The passive knee prosthesis is part of the CYBERLEGs-Project.

Keywords: Prosthetic devices, Locomotion and manipulation in robots and biological systems, Biological systems modeling
Abstract: In human gait locomotion analysis, which is one useful method for efficient physical rehabilitation to define various quantitative evaluation indices, ground reaction force, joint angle and joint loads are measured during gait. On the other hand, the analysis of the correlation in the recorded joint motion extracts a few simultaneously activating segmental coordination patterns, and the structure of the intersegmental coordination is attracting attention to an expected relationship with a control strategy. However, this procedure has not been applied to trans-femoral prosthetic gait locomotion yet. Therefore, in this paper, joint angle of the lower limb in gait locomotion of healthy subjects and trans-femoral amputee is focused and motion mode is extracted as intersegmental coordination pattern by applying the evaluation method based on singular value decomposition. Furthermore, quantitative evaluation based on comparative verification of analytical results is aimed. Concretely, conventional three-dimensional motion analysis system is used to measurement and analysis of gait locomotion. Moreover, each motion mode is extracted when one gait cycle is divided into four phases as two double support phases and single support phase in the stance phase and the swing phase. Trajectory of gravity point in gait locomotion of each subject is also calculated. Finally, differences of gait locomotion between healthy subjects and trans-femoral amputee are considered as a comparison and the effectiveness of quantitative evaluation is validated.　As a result of the experiments, analysis and consideration, the effectiveness of the method using singular value decomposition of each joint angle and kinematic consideration, as well as biomechanics, is validated because it can quantitat

Keywords: Prosthetic devices, Biological systems modeling, Biomechatronic and human-centred design
Abstract: Bench tests are not sufficient to compare the performance of foot prostheses since only the dynamic behavior can be evaluated in the testing machines. This work supplements the bench tests described by several standards with a single patient (below knee amputee) kinematic evaluation using the concept of Roll-Over Shape to compare two low-cost prostheses against the sound limb. The Roll-Over Shape is generated first, by experimentally obtaining the trajectories of the patient’s ankle, knee, and center of pressure throughout the stance phase of the gait cycle; and second by mathematically transforming these trajectories into a shank-based coordinate system with the ankle as origin. Unlike previous work that compares the roll-over parameters obtained via the quasi-static method, this paper compares the roll-shape of a trans tibia amputee wearing eather a SACH foot, or a high energy return foot (TEC-LIMBS), and the contralateral sound limb. The outcomes demonstrate a lower difference in the Roll-over radius of the TEC-LIMBS foot with respect to the sound limb (<10%), while the SACH foot presents a greater difference with respect to the sound limb (>40%). The findings of the tests performed in this study indicate that the TEC-LIMBS foot has a better kinematic performance than the SACH type prosthesis, a prosthesis widely used for humanitarian purposes.

Keywords: Prosthetic devices, Locomotion and manipulation in robots and biological systems, Biologically-inspired systems
Abstract: The human gait shows significant differences in the ankle movements during turning and sidestep cutting compared to straight walking, especially in frontal plane. This suggests that the next advancement in lower extremity assistive devices is to extend their design and control to the frontal plane. In this paper, the concept of a multi-axis powered ankle-foot prosthesis is introduced and its feasibility is shown by a proof of concept prototype of a cable-driven, multi-axis ankle-foot prosthesis. The design kinematics and its ankle joint’s mechanical impedance in non-load bearing conditions are evaluated and discussed. It is shown that the developed prototype is capable of closely mimicking the ankle movements in both sagittal and frontal planes during turning and walking on straight path with passive mechanical impedance in sagittal and frontal planes comparable to the ones of the human ankle.

Keywords: Prosthetic devices, Rehabilitation and assistive robotics
Abstract: Development of an anthropomorphic and dexterous robotic prosthetic device becomes an interesting research topic. An anthropomorphic transradial prosthetic arm is proposed in this paper. In order to generate the wrist flexion/extension and ulna/radial deviation a novel wrist mechanism is proposed based on parallel prismatic manipulators. It is expected to realize high speed operation, higher positional accuracy and anthropomorphic features by means of size and weight using the proposed mechanism. The prosthetic arm consists of an under-actuated hand as the terminal device. The hand mechanism is capable of providing the grasping adaptation. With the intention of verifying the effectiveness of the mechanisms in motion generation, a motion simulation and kinematic analysis are carried out.

Attachments: Video
Keywords: Biomechatronic and human-centred design, Biologically-inspired systems, Wearable assistive and augmenting devices
Abstract: Variable compliant actuators play a key role in the development of efficient biomechatronic systems since energy can be stored in the compliant element thus leading to consumption reduction. In this paper, experimental results comparing passivity-based control (PBC) and feedback linearization (FL) for motion control of an actuator with variable torsional stiffness (VTS) aiming at applications like prosthetic knee joints are presented. The concept of VTS and the experimental setup are described and a mathematical model of the latter one is derived. Based on this, a control architecture consisting of an extended Kalman filter (EKF) to estimate the velocities, a friction compensation as well as the mentioned controller types is developed. Both control methods are analyzed in terms of accuracy, dynamics and their control torque. FL and PBC lead to a stable control with high performance whereas the robustness is low by reason of the model-based control design. FL is superior to the PBC in terms of accuracy and control torque, which is mainly due to the high sensitivity of PBC regarding the discrete position signals. In addition, it is shown that FL can be applied for stable operation near the second natural frequency for different stiffness values.

Keywords: Biologically-inspired systems, Rehabilitation and assistive robotics, Wearable assistive and augmenting devices
Abstract: A novel actuator is presented that merges traditional electromechanical motors and multistable composite structures. Previously, it has been shown that these structures are able to arrange themselves in multiple stable configurations corresponding to local minima of their strain energy. When coupled with an electromechanical motor as proposed in this article, the resulting actuator shows significant benefits. These are in terms of safety, energy saving and control implementation using the compliance of the overall structure, the particular shape of the strain energy landscape, and the accurately predictable non-linear behavior. Hence the proposed actuator is well-suited for robotics applications. The parameters characterizing the design of the transmission are analyzed, and a physical model is developed. A case study is presented in which the performance for a particular configuration of the system is evaluated and reported. A conceptual application of the proposed actuator is discussed for assistive robotics, where new perspectives on the use of non-rigid transmission elements might become beneficial in terms of safety and energy harvesting.

Keywords: Neuroengineering, Rehabilitation and assistive robotics
Abstract: We propose and describe two force-feedback based actuation systems to support accurate robot-mediated wrist motor protocols during fMRI: a co-located actuation approach and a remote actuation system based on a plastic cable- conduit transmission. To decouple the load from the non-linearities of the actuators and to enable force feedback, in both system we include physical compliance and additional position and force sensing capabilities. Through a detailed description of the actuators design, we show how the choice between co-located and non co-located actuation influences the design of a wrist exoskeleton, to be used for robot-mediated protocols during continuous fMRI, resulting in a parallel MR-compatible wrist robot design and a serial MR-compatible wrist robot design respectively.

Keywords: Micro/nano technologies in medicine and biology, Technology for assisted surgery and diagnosis, Locomotion and manipulation in robots and biological systems
Abstract: Recently, a conventional capsule endoscope was developed and has been used for a diagnosis to make up for the limitations of conventional flexible endoscopy. However, the capsule endoscope has also some limitations and low diagnostic effectiveness because of its passive movement through the peristaltic motion of digestive organs. To overcome these problems, there are several researches about active mobility of capsule endoscope. In this paper, we proposed helical motion and locomotion mechanism for magnetic capsule endoscope using the electromagnetic actuation (EMA) system. Through the combination of the magnetization direction of the capsule endoscope prototype and the precessional magnetic field which can be generated by 3-pairs of Helmholtz coils, the capsule endoscope prototype can show a precessional motion. In addition, the capsule endoscope prototype can move toward an aligned direction by a gradient magnetic field of Maxwell coils. First, we fabricated a capsule endoscope prototype with a desired magnetization direction and verified its scanning function through the helical motion of the capsule endoscope prototype in mock-up of tubular digestive organs. Second, the capsule endoscope prototype also has a propulsion force to the perpendicular direction of axial vector when it track the helical path, and this force make the capsule endoscope prototype to attach the inner wall of tubular environment. Finally, through the planar locomotion test in stomach phantom, we have verified the feasibility of the capsule endoscope using an electromagnetic actuation system.

Keywords: Micro/nano technologies in medicine and biology, Surgical navigation and robotics, Locomotion and manipulation in robots and biological systems
Abstract: Capsule endoscope is commercial design product used as a medical device for endoscopy test in the small intestine preferably. This paper presented a novel conceptual design and power mechanism in order to perform a capsule endoscope robot with micro-hydraulic biopsy tools system. The capsule endoscope presented can moves as active device, powered externally by an electro-magnetic actuation system (EMA). The EMA system can be frequency adjust to activate the micro-hydraulic pump as the main power generator to perform the micro-actuator and/or micro-biopsy tool. The conceptual design is focused in two capsule containers; these are proposed to be able to obtain additional space for the biopsy tools. Preliminary test of the micro-pump power by EMA system are presented for future application of capsule endoscope with active motion maneuvers and micro-biopsy tools operation in real-time.

Keywords: Rehabilitation and assistive robotics, Human-machine interaction
Abstract: A systematic approach for the supervision-based safe motion control of mobility assistive robots based on invariance control is presented. It allows the formulation of safety features in the form of a constraint admissible state space region that can be kept invariant by proper switching between a nominal and a corrective controller whenever a predefined safety constraint is about violation. Boundaries on the human-robot distance are considered critical safety features for human forward fall and human-robot collision avoidance. The nominal and corrective controller as well as the switching policy are derived. The approach is validated in simulations and experiments and shows high potential for building a systematic safety framework for mobility assistive robots.

Keywords: Rehabilitation and assistive robotics, Biological systems modeling, Human-machine interaction
Abstract: A framework to generate predictive simulations is proposed to investigate the influence of system’s mass on manual wheelchair locomotion. The approach is based on a model of wheelchair propulsion dynamics and an optimal control formulation. In this study, predictive simulations of steady-state wheelchair locomotion are generated for different combinations of model mass and uphill slope inclination angle. The results show that the influence of system’s mass is negligible in level surfaces in steady-state, a finding which agrees with experimental observations in the literature. On the other hand, the results show that the influence of mass on slopes is critical, with large increases in propulsion effort with system’s mass, even for slight inclination angles. This shows the importance of reducing wheelchair mass for improving locomotion performance, particularly in overcoming obstacles and ramps. Decreasing the wheelchair’s mass may not be sufficient. Therefore, and on the light of these findings, we propose the reduction of system’s apparent mass through the implementation of an impedance control scheme in power-assisted wheelchairs.

Keywords: Wearable assistive and augmenting devices, Rehabilitation and assistive robotics, Human-machine interaction
Abstract: Cervical Cord Injury(CCI) causes a form of upper limb dysfunction. In an individual with C5-level CCI, which is the most frequent of all eight types of CCI, force can be applied in the direction of flexion by the biceps brachii, while extension force cannot be applied by the triceps brachii. Without the ability of the triceps brachii to exert this force, individuals with a C5-level CCI cannot propel a wheelchair along a carpet or sloping road. In this study, we developed a propulsion assistance control system for wheelchair operation using an exoskeletal robot. We first analyzed the difference between the wheelchair operations of a healthy person and a C5-level CCI. We then designed a control model that included a user and a wheelchair. The wearer's arm was modeled as a two-link manipulator, and the extension force and hand position were estimated using the equation of motion. The estimated extension force was compared with the driving force required to operate a wheelchair with the target velocity defined at the time of flexion of an arm. We then applied the proposed method via an exoskeletal robot. The effectiveness of the proposed method is demonstrated by experimental of wheelchair operation with C5-level CCI.

Attachments: Video
Keywords: Rehabilitation and assistive robotics, Locomotion and manipulation in robots and biological systems, Surgical navigation and robotics
Abstract: In this work, we present a motion control scheme for a robotic mobile platform using low-cost vision sensor to update encoder values. We track the pose of a power wheelchair using wheel encoders along with a Microsoft Kinect camera. Two methods of pose estimation are implemented and tested. These methods are a) encoder-based odometry and b)ICP(Iterative Closest Point)-based optimized odometry. We evaluate the performance of each method using precise wheelchair pose ground truth data acquired via a state-of-the-art VICON system with eight motion capture cameras. Offline data processing is performed to refine the ICP parameters and estimate the covariance matrices of the Kalman filter. The offline data processing results demonstrate that our ICP-based optimized odometry has very accurate pose tracking. By implementing our control scheme, the position error is improved by a factor of 15 and the localization orientation error is improved by a factor of 13. To demonstrate the robustness of our approach, we apply it for real-time obstacle avoidance. A wheelchair-mounted robotic arm (WMRA) is also included in this platform and will be used for future work on combined mobility and manipulation control with sensor assistance.

Keywords: Rehabilitation and assistive robotics, Human-machine interaction
Abstract: This work proposes the implementation and validation of a new sensor fusion strategy based on force sensors and LRF (Laser Range Finder) to control a robotic walker. This approach combines user information about forearm reaction forces and gait kinematics from the legs scanning localization, to develop a more natural, safer and adaptable human-walker interaction. The work was carried out in four phases. First, a robotic walker platform was developed and the sensor subsystems were integrated. Second, a sensor fusion strategy to obtain the control parameters are defined. Third, the control strategy is presented. Finally, an experimental study to evaluate the sensor architecture and control was developed. One of the advantages of the human-walker interaction here proposed is the computational efficiency. The sensor processing algorithms and the control strategy are executed in real-time, showing stable performance with human speed changes.