Robotic Mechanism Driven Agonistically : Collision Experiment and Control of Collision Force

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The object of this project is to increase capabilities of robots by introducing new mechanisms, control methods, and concepts such as interactions with working environment so that they can find new applications. The following four subjects were studied : mechanism driven agonistically ; manipulation of flexible object ; control of space manipulator ; control of underwater manipulator.1.Agonistically driven mechanism One link mechanism driven by a pair of pneumatic artificial muscles was studied to find relations between the air pressure of each muscle and the joint torque/stiffness : (1)The joint torque and stiffness can be independently adjusted by controlling the each air pressure ; (2)Lower stiffness of the joint reduces a collision force when the link comes contact with the environment ; (3)These characteristics were confirmed experimentally as well.2.Manipulation of flexible object by robot Trajectory planning to deform a flexible plate grasped by a manipulator was studied to find an energy effective path. A new concept, which we named manipulative compliance ellipsoid, was introduced to define the manipulability. A load estimator was found effective in the real time control even if the elastic characteristic of the plate is unknown.3.Control of space manipulator We studied the following : (1)Application of an adaptive control to follow a planned trajectory even after grasping an unknown object ; (2)Orientation control by using the nonholonomic characteristics of the space robot ; (3)Real time planning of trajectory. Effectiveness of proposed control methods for respective tasks was confirmed by simulation and/or experiments.4.Control of underwater manipulator In the digital control special attentions have to be paid to the nonminimum phase characteristic and variable nonlinearity of a plant, both features are inherent in a underwater manipulator. A new design algorithm was proposed with simulation and experimental results showing validity of our method.