Robotic gait trainers are used all over the world for the rehabilitation of stroke patients, despite relatively little is known about how the robots should be controlled to achieve the optimal improvement. Most devices control complete joint trajectories and assume symmetry between both legs by either a position or an impedance control. However we believe that the control should not be on a joint level but on a subtask level (i.e. foot clearance, balance control). To this end we have chosen for virtual model control(VMC) to define a set of controllers that can assist in each of these tasks. Thus enabling the exoskeleton to offer selective support and evaluation of each substask during rehabilitation training. The aim of this explorative pilot study was to assess the performance of a VMC of the step height and to assess if selective control of the step height left the remaining of the walking pattern unaffected. Four young healthy subjects walked on a treadmill with their legs and pelvis attached to the lopes exoskeleton in 3 different conditions: (1) providing minimal resistance, (2) control of the left step height with a low stiffness (3) control of the step height with a large stiffness. We have shown that it is possible to exert a vertical forces for the support of foot clearance during the swing phase. The higher stiffness of the VMC resulted in a greater change of the step height, which was achieved by a larger increase of the maximal hip and knee flexion compared to the low stiffness condition. The control of the step height resulted in minor changes in the cycle time and swing time. The joint angles also showed only minor changes. The preliminary results suggest that we were able to control a subtask of walking, while leaving the remaining walking trajectory largely unaffected. In the near future, control of other subtask will be implemented and evaluated in isolation and in conjunction with each other.

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Based on the human-machine intelligent robot system of lower extremity carrying exoskeleton, the new control method is provided, where the virtual torque control is improved. The exoskeleton model is built using SimMechanics in Matlab. The dynamics mathematics model is gotten by study the human walking to construct the controller. The controller in virtual torque control uses nonlinear direct force control while not PID control. The control law presented in this paper simplifies the controller design and not making use of any information about the operator or of any of the mechanical characteristics of the human-machine interface. The most important of this method is the mass properties need not be identified, which overcomes the maximum defect of the virtual torque control. Simulation results show the valid of the given method.

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Research in robot-assisted gait rehabilitation has seen significant improvements in human-robot interaction, thanks to high performance actuator technologies and dedicated control strategies. In this context we propose a combination of lightweight, intrinsically compliant, high power actuators (pleated pneumatic artificial muscles, PPAMs) with safe and adaptable guidance along a trajectory by means of proxy-based sliding mode control (PSMC). Treadmill walking experiments performed by a healthy subject wearing a powered knee exoskeleton indicate two main challenges: synchronizing the compliant device and the subject, and tuning the control parameters in view of safe guidance. The exoskeleton is able to compliantly guide the test person’s knee along various target trajectories, while ensuring a smooth response to large perturbations.

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We are developing a wearable exoskeleton rotational haptic interface that will fit the human body. First, we developed a force sensor to measure the rotational moment of rotational tasks at the wrist and measured the rotational moment of important tasks. Then, we tried to develop a prototype of the exoskeleton rotational haptic interface.

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Based on pneumatic artificial muscles, the force feedback dataglove is an important interface designed for dexterous manipulations with virtual environments, which provides force display for every segment of the thumb, index and middle finger. The typical mechanism of exoskeleton structure is adopted to allow full range-of-motion of the hand, with the actuator system placed on the forearm. The exoskeleton structure also serves as the hand position measurement function, by integrating non-contact Anisotropic Magneto-resistive sensors. The actuator consists of the pneumatic muscle and brake system. The contracting force of muscle transmitted through the tendon sheath structure is measured by the cantilevered beam sensor installed inside the pedestal. The single PC-based control interface comprises of an industrial computer, pneumatic valves and electronic ISA-bus cards for reading the sensors and implementing pressure control. The grasping force calculated according to the object deformation as well as its modeled compliance is displayed to the finger by regulating the pressure in the muscles based on the isometric characteristics

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