53 research outputs found

    Motion Control for an Intelligent Walking Support Machine

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    Walking is a vital exercise for health promotion and fundamental ability necessary for everyday life. Up to now, many robots for walking support or walking rehabilitation of the elderly and the disabled are reported. In this paper, a new omni-directional walking support machine is developed. The machine can realize walking support by following the user's control intention which is detected according to the user's manipulation. However, the motion of the machine is affected by the nonlinear frictions, center-of-gravity (COG) shifts and loads changes caused by users. It is necessary to improve the machine's motion performance to follow the user intention and support the user. Therefore, this paper describes a motion control method based on digital acceleration control to deal with the problem of nonlinear frictions, COG shifts and loads changes. Simulations are executed and the results demonstrate the feasibility and effectiveness of the proposed digital acceleration control method

    Improving the Motion Performance for an Intelligent Walking Support Machine by RLS Algorithm

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    To make the old people and handicapped people move easily by themselves, an omni-directional walking support machine (WSM) has been developed. In our previous study, to improve the motion performance of the WSM, a digital acceleration control method has been developed to deal with the nonlinear friction. However, the design of the digital acceleration controller requires to know the exact plant parameters of the WSM which are variable due to center of gravity (COG) shift and load changes. The change of the plant parameters affects the motion performance of the digital acceleration control system. Therefore, in this paper, a discrete-time system identification method using recursive least squares (RLS) algorithm is proposed to online identify the WSM’s plant parameters for the digital acceleration controller. Simulations are executed and compared with the digital acceleration controller without using RLS algorithm, and the results demonstrate the feasibility and effectiveness of the proposed control method

    Anthropomorphic Dual-Arm Coordinated Control for a Single-Port Surgical Robot Based on Dual-Step Optimization

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    Effective teleoperation of the small-scale and highly-integrated robots for single-port surgery (SPS) imposes unique control and human-robot interaction challenges. Traditional isometric teleoperation schemes mainly focus on end-to-end trajectory mapping, which is problematic when applied to SPS robotic control, especially for dual-arm coordinated operation. Inspired by the human arm configuration in boxing maneuvers, an optimized anthropomorphic coordinated control strategy based on a dual-step optimization approach is proposed. Theoretical derivation and solvability of the problem are addressed, and the effectiveness of the method is further demonstrated in detailed simulation and in-vitro experiments. The proposed control strategy has been shown to perform dexterous SPS bimanual manipulation more effectively, involving less instrument-interference and is free from singularities, thereby improving the safety and efficiency of SPS operations

    Preliminary in vivo evaluation of a needle insertion manipulator for central venous catheterization

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    Central venous catheterization is associated with potential complications secondary to accidental puncture, including venous bleeding and pneumothorax. We developed a system that avoids these complications and simplifies the procedure using a robot to provide puncture assistance. We herein report a puncture experiment conducted in vivo in a porcine to evaluate the manipulator. The right and left jugular veins of a pig were punctured five times each through both opened and unopened skin at a puncture angle and speed. A venous placement rate of 80% was obtained with opened skin. A much lower rate of 40% was obtained with unopened skin. One of five attempts in opened skin was unsuccessful, likely because of the stick-slip phenomenon. This system was effective for jugular venous puncture of opened skin. Future studies should focus on puncture conditions that facilitate needle placement, inhibit the stick-slip phenomenon, and minimize needle bending due to the presence of skin. © 2014 Kobayashi et al.; licensee Springer.1
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