Whole-Body Motion Tracking for a Quadruped-on-Wheel Robot via a Compact-Form Controller With Improved Prioritized Optimization

Abstract

This paper develops a more general dynamics controller to generate whole-body behaviors for a quadrupedon-wheel robot. To track the quadruped centroidal motion, the wheeled motion is achieved by combining the wheel contact constraints and the centroidal momentum/dynamics model. The dynamics controller is based on a new hybrid hierarchical and prioritized weighted optimization framework. We propose one concept of a recursively updated dynamics model and this model enables to integrate the new prioritized weighted scheme in the hierarchical framework. In contrast with the conventional weighted scheme, we propose to use null-space projections among its sub-tasks. Then the prioritized impedance controller is proposed and integrated in our dynamics model, which enables to influence the hierarchical and prioritized weighted tasks in a decoupled way. The task accelerations in the two schemes are extracted with quadratic forms depending on the actuated torque and the prioritized impedance force using null-space based inverse dynamics. The inequality constraints are modified to ensure the compatibility with the hybrid convex optimization. This dynamics controller is more general and its algorithm is given completely which enables our robot to track the centroidal motion on rough terrain and handle other missions in three simulation scenarios.

State of the art and future trends in obstacle-surmounting unmanned ground vehicle configuration and dynamics

“…Viragh [71] addressed a trajectory optimizer for quadrupedal robots with actuated wheels. Du [72] developed a more general dynamics controller to generate whole-body behaviors for a quadruped-on-wheel robot. Table I is summarized to present the worldwide research status of UGV platforms.…”

Combined Sampling and Optimization Based Planning for Legged-Wheeled Robots

“…To simplify the combinatorial nature of contact schedule planning for legged robots, researchers often use cyclic gaits to restrict the solution space size. Planning with cyclic gaits has been widely used for quadrupedal robots with point feet ( [11], [12], [13], [14]) and more recently, it has been applied to hybrid robots as well ( [1], [15], [5]). Presented controllers run under the flat ground assumption in an Model Predictive Control (MPC) fashion with a prediction horizon of about 2 s. Such a strategy relies on reactive control behavior from MPC, and while it can traverse small irregularities in the terrain, large obstacles still pose an issue.…”

“…A powerful tool used to cope with the increased complexity is Trajectory Optimization (TO). TO has been shown to work well on hybrid systems with many Degrees of Freedoms (DoFs) ( [1], [4], [5]). However, optimization is prone to local minima.…”

Modeling and invariably horizontal control for the parallel mobile rescue robot based on PSO-CPG algorithm

“…The traditional kinematic control methods are often difficult to meet the requirements of the invariably horizontal control of the parallel mobile rescue robot. With the development of intelligent bionic control technology, many methods have become effective ways to solve this problem such as CPG model, neural network, and reinforcement learning [3][4][5].…”