Integration And Usage Of A Ros-Based Whole Body Control Software Framework

ControlIt! is a ROS-based high performance feedback control framework that enables WholeBody Control (WBC) algorithms to be implemented, instantiated, and integrated into ROS applications. It operates above individual joint controllers but below planners and takes a holistic view of the robot to achieve multiple simultaneous objectives. Such capabilities are particularly useful for highly redundant and multi-branched robots like humanoids where the large number of degrees of freedom (DOFs) and intrinsic multi-tasking like reaching for an object while maintaining balance requires advanced feedback control strategies. ControlIt! provides two software abstractions, a compound task and a constraint set, that enables users to configure, use, and integrate whole body controllers. The compound task consists of prioritized tasks with controllers that operate in a relatively low dimensional space compared to the number of joints. The constraint set specifies physical limits of the robot like points of contact with the environment and mechanical couplings between joints. ControlIt! comes with an implementation of the Whole Body Operational Space control (WBOSC) algorithm, one of the original WBC algorithms. Through prioritized null-space projection, WBOSC achieves each tasks' objectives subjected to limitations from higher priority tasks and the constraint set. Using tasks and constraints, users can make high-DOF multi-branched robots execute sophisticated multi-objective and adaptive behaviors. This chapter presents ControlIt! and provides examples of advanced whole body behaviors it enables.