Publication | Closed Access
High degree-of-freedom dynamic manipulation
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0
References
2012
Year
Dynamic ManipulationRobot KinematicsEngineeringDexterous ManipulationField RoboticsIntelligent RoboticsObject ManipulationAdvanced Motion ControlTrajectory PlanningKinesiologySystems EngineeringLegged RobotKinematicsRobot LearningHealth SciencesMechatronicsRobot HardwareDynamic LiftingRobot ControlMechanical SystemsRobotics
High‑degree‑of‑freedom dynamic mobile manipulation enables robots to perform difficult tasks, but requires all DOFs to be active, generates high dynamic forces, and demands robust balance throughout tasks. The study investigates using a legged robot’s body and legs to enhance the strength, velocity, and workspace of an integrated manipulator for dynamic manipulation. Trajectory optimization and CMA‑ES are used to generate 13‑dimensional open‑loop behaviors for a 28‑DOF quadruped (BigDog), producing feed‑forward terms that improve tracking and reduce controller gains while respecting torque, velocity, kinematic, and center‑of‑pressure constraints. Hardware tests on a balancing quadruped with a human‑arm‑like manipulator show dynamic lifting and throwing of 16.5‑kg cinder blocks with human‑like motions, and coordinated body motion increases payload capacity.
The creation of high degree of freedom dynamic mobile manipulation techniques and behaviors will allow robots to accomplish difficult tasks in the field. We are investigating the use of the body and legs of legged robots to improve the strength, velocity, and workspace of an integrated manipulator to accomplish dynamic manipulation. This is an especially challenging task, as all of the degrees of freedom are active at all times, the dynamic forces generated are high, and the legged system must maintain robust balance throughout the duration of the tasks. To accomplish this goal, we are utilizing trajectory optimization techniques to generate feasible open-loop behaviors for our 28 dof quadruped robot (BigDog) by planning the trajectories in a 13 dimensional space. Covariance Matrix Adaptation techniques are utilized to optimize for several criteria such as payload capability and task completion speed while also obeying constraints such as torque and velocity limits, kinematic limits, and center of pressure location. These open-loop behaviors are then used to generate feed-forward terms, which are subsequently used online to improve tracking and maintain low controller gains. Some initial results on one of our existing balancing quadruped robots with an additional human-arm-like manipulator are demonstrated on robot hardware, including dynamic lifting and throwing of heavy objects 16.5kg cinder blocks, using motions that resemble a human athlete more than typical robotic motions. Increased payload capacity is accomplished through coordinated body motion.