Equilibrium Points A unifying abstraction for motor control Xue Gu Dana H Ballard University of Texas Computing with a physical device Passive energy storage Mechanical compliance Directly related ideas Faloutsos et al Computers and Graphics 25 6 2001 933 953 Gunther and Ruder Biological Cybernetics 89 89 106 2003 Torres Zipser J Neurophys 88 2355 2367 2002 The Model Motor Simulation Method Use GD on distance error function for kinematics solution Energy consumption optimization with constraints to end effector Motor Simulation in Experiments fastracks Four fastracks are attached to the arm to capture movement data Weights are attached to different segments of the arm to test how the end postures changes weights attached Simulation comparison with human data weights on bicep weights on forearm weights on hand Movement Execution Theory Dynamic skeleton system Springs apply torques to the system is spring stiffness and is viscosity With different and different K B trajectories are generatedK B Movement Execution Implementation Movement execution Use springs in Vortex 2 3 a physics simulation package to simulate muscles Spring controls extension and flexion Planar Arm Reaching Movement Data Comparison 1 End effector trajectories fitting vx t y Speed profile along x vy x human data ooo prediction t Speed profile along y Movement Data Comparison 2 Joint profile comparison Shoulder Elbow Wrist Model Extension of Walking Bi pedal walking 4 Via points are defined for one cycle of walking Every leg has 3 springs which control both extension and flexion Walking Walking Profile Comparison Human data from Boston dynamics Hip Model simulation data Knee Ankle Walking II Complex Movements Generation High DOF system as complicated as human body is hardly tractable Human body parts move in relatively independent manners Divide and conquer Motor routines defined for body parts Motor synergies are used to combine complex movements Motor Synergies Two or more tasks can be planned at the same time during motor simulation Sitting down hip reaches to destination Balancing center of mass remains above the feet Hand Grasping Routine 14 degrees of freedom Grasping is done by setting the EPs inside the objects No high accuracy is required during planning Complex Movements Complex Movements II Graziano Proposed Organization Plan Segement SMA Premotor ctx Execute Segement Spinal cord Segment 1 Segment 2 Segment 1 Segment 2 Movement Control Summary 1 2 Complex Movements Executed in Segments Each Segment Two phases Offline motor simulation phase Online motion Execution phase 3 End posture for current task Equilibrium point theory Abstract spring muscle control model Motor synergies Different routines defined for body parts Combination for whole body movements
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