A novel control methodology for master-slave systems using passive force feedback has been proposed by the authors. The methodology solves the conventional problems of previously developed master-slave systems with force feedback, such as oscillations, complex structures and complicated control algorithm. In the present paper a multi-fingered exoskeleton haptic device (master hand) with passive force feedback function is developed. First, the exoskeleton master hand with three fingers (12 degrees of freedom) is designed and implemented. Each finger of the master hand consists of a link mechanism with elastic-shaft joints and clutches. Using link mechanisms, the master hand measures fingertip positions and angles of index finger middle finger and thumb. Furthermore, it also enables passive force feedback to an operator by the same link mechanism used for the geometric measurements. Then, a virtual reality system of human hand is constructed using the master hand and the control methodology. Using the system, sensory evaluations are conducted on human subjects to confirm the usability of the developed master hand and the possibility of the control methodology in the virtual reality system. As a result, the subjects possibly recognize the stiffness of the objects in the virtual environment.

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The Defense Advanced Research Projects Agency (DARPA) is funding the development of exoskeletal devices that are intended to increase the speed, strength, and endurance of soldiers in combat environments. The purpose for this work was to provide guidance for the design of the lower limbs of an exoskeletal device. In providing design guidance, the authors had two goals. The first goal was to provide estimates of the angles, torques, and powers for the ankles, knees, and hips of an exoskeleton based on data collected from humans. The second goal was to calculate the mean power required for various tasks and the total peak power needed by the lower limbs of the exoskeletal device for two «typical» infantry missions.

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A novel control methodology for master-slave systems using passive force feedback has been proposed by the authors. The methodology solves the conventional problems of previously developed master-slave systems with force feedback, such as oscillations, complex structures and compli-cated control algorithm. In the present paper, a multi-fingered exoskeleton haptic device (master hand) with passive force feedback function is developed. First, the exoskeleton master hand with three fingers (12 degrees of freedom) is designed and implemented. Each finger of the master hand consists of a link me-chanism with elastic-shaft joints and clutches. Using link mechanisms, the master hand measures fingertip positions and angles of index finger, middle finger and thumb. Furthermore, it also enables passive force feedback to an operator by the same link mechanism used for the geometric measurements. Then, a virtual reality system of human hand is constructed using the master hand and the control methodology. Using the system, sensory evaluations are conducted on human subjects to confirm the usability of the developed master hand and the possibility of the control methodology in the virtual reality system. As a result, the subjects possibly recognize the stiffness of the objects in the virtual environment.

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The aim of this study was to investigate the biomechanics and motor co-ordination in humans during stair climbing at different in-clinations. Ten normal subjects ascended and descended a five-step staircase at three different inclinations (24°, 30°, 42°). Three steps were instrumented with force sensors and provided 6 dof ground reactions. Kinematics was analysed by a camera-based opto-electronic system. An inverse dynamics approach was applied to compute joint moments and powers. The different kinematic and kine-tic patterns of stair ascent and descent were analysed and compared to level walking patterns. Temporal gait cycle parameters and ground reactions were not significantly affected by staircase inclination. Joint angles and moments showed a relatively low but sig-nificant dependency on the inclination. A large influence was observed in joint powers. This can be related to the varying amount of potential energy that has to be produced (during ascent) or absorbed (during descent) by the muscles. The kinematics and kine-tics of staircase walking differ considerably from level walking. Interestingly, no definite signs could be found indicating that there is an adaptation or shift in the motor patterns when moving from level to stair walking. This can be clearly seen in the foot placement: compared to level walking, the forefoot strikes the ground first—independent from climbing direction and incli-nation. This and further findings suggest that there is a certain inclination angle or angular range where subjects do switch be-tween a level walking and a stair walking gait pattern.

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This article models a pneumatic system consisting of double-acting or single acting cylinder and a servovalve with the goal of providing an insight into pneumatic design and control requirements for Berkeley Exoskeleton (http://www.me.berkeley.edu/hel/). The modeling approach uses the thermodynamic principles of energy and mass conservation. We demonstrate that pneumatic systems suffer from two effects: unwanted dynamics due to gas compressibility and discontinuous nonlinearities in the servovalves due to choked flow. To obtain a wide control bandwidth, one needs to model these effects thoroughly

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