Previous demonstrations of brain-machine interfaces have shown the potential for controlling a neuroprosthesis under pure motion control, i.e. predicting end effector kinematics from neural ensemble activity. For real world tasks, however, pure motion control lacks the information required for versatile manipulation in which the dynamic interactions of forces and torques between the musculoskeletal system and the environment play a crucial role. Thus, our current efforts aim at enabling a subject using a brain-machine interface to volitionally control the mechanical impedance of the prosthetic device. Here we propose the use of a two-link arm exoskeleton to investigate upper limb stiffness in non-human primates. We show that the device can be used to experimentally measure end-point limb stiffness, as well as to control the stiffness when the exoskeleton is used in slave-robot mode. Experimental results show that this platform allows for both stiffness measurement and control of the robotic device.

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This paper presents the design of IKO (IKerlanpsilas Othosis), an upper limb exoskeleton oriented to increasing human force during routine activity at the workplace. It can be considered as a force amplification device, conceived to work in collaboration with the human arm and implementing biomimetic principles. The proposed design is intended to find the best compromise between maximum reachable workspace and minimum moving mass, which are the key factors for obtaining an ergonomic wearable exoskeleton. Power transmission is based on Bowden cables. Dynamic performance and control strategies have been evaluated for the electrical motors and pneumatic muscles used.

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This paper presents the design and the optimal dimensional synthesis of a reconfigurable, parallel mechanism based, force feedback exoskeleton for the human ankle. The primary use for the device is aimed as a balance/proprioception trainer, while theexoskeleton can also be employed to accommodate range of motion (RoM)/strengthening exercises. Multiple design objectives for several physical therapy exercises are discussed and classified for the design of the rehabilitation device. After kinematic structures of mechanisms that are best suited for the physical therapy applications are selected, an optimization problem to study the trade-offs between multiple design criteria is formulated. Dimensional synthesis is performed to achieve the maximum stiffness of the device, while simultaneously maximizing the actuator utilization, using a Pareto-front based framework. An ldquooptimalrdquo design is selected studying the Pareto-front curve and taking the primary and secondary design criteria into account. Once the dimensions of the device are decided, reconfigurability is built into the design such that the device can be arranged as a 3UPS manipulator to administer RoM/strengthing exercises and as a 3RPS manipulator to support balance/proprioception training. Metatarsophalangeal joint exercises are also enabled through a reconfigurable design of the foot plate. Details of the final design of the ankle exoskeleton, CAD snapshots, and an early prototype of the device are also presented.

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Robotics is emerging as a promising tool for training of human functional movement. The current research in this area is focused primarily on upper extremity movements. This paper describes novel designs of three lower extremity exoskeletons, intended for gait assistance and training of motor-impaired patients. The design of each of these exoskeletons is novel and different. Force and position sensors on the exoskeleton provide feedback to the user during training. The exoskeletons have undergone limited tests on healthy and stroke survivors to assess their potential for treadmill walking. GBO is a gravity balancing un-motorized orthosis which can alter the gravity acting at the hip and knee joints during swing. ALEX is an actively driven leg exoskeletonwhich can modulate the foot trajectory using motors at the joints. SUE is a bilateral swing-assist un-motorized exoskeleton to propel the leg during gait.

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This paper proposes an approach of generating the gait pattern that Asian Institute of Technology’s Leg EXoskeleton (ALEX) and its wearer can walk safely with the passing criteria of Zero Moment Point (ZMP) theorem for static and dynamic considerations, respectively. ALEX has 12 DOF (6 DOF for each leg: 3 at the Hip, 1 at the knee and 2 at the ankle), controlled by 12 DC motors. The CAD drawing and assembly of ALEX are exported directly to MATLAB’s Simulink/SimMechanics simulation environment to assure accurate positioning of center of gravity (CG) and moment of inertia of each of the links that make up this 12 DOF robot. The gait pattern is visually observed in virtual environment (VR) using 3D VRML interpreter while ZMP trajectory is monitored using MATLAB’s 2D graphics representation. With this developed simulation of ALEX, the robot can be tested to confirm its balance gait motion prior to the real implementation on the physical system that could cause serious damages to the robot itself and its fragile electronic devices.

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