A Real-Time Planning and Control Framework for Robust and Dynamic Quadrupedal Locomotion

Abstract

Legged locomotion poses significant challenges due to its nonlinear, underactuated and hybrid dynamic properties. These challenges are exacerbated by the high-speed motion and presence of aerial phases in dynamic legged locomotion, which highlights the requirement for online planning based on current states to cope with uncertainty and disturbances. This article proposes a real-time planning and control framework integrating motion planning and whole-body control. In the framework, the designed motion planner allows a wider body rotation range and fast reactive behaviors based on the 3-D single rigid body model. In addition, the combination of a Bézier curve based trajectory interpolator and a heuristic-based foothold planner helps generate continuous and smooth foot trajectories. The developed whole-body controller uses hierarchical quadratic optimization coupled with the full system dynamics, which ensures tasks are prioritized based on importance and joint commands are physically feasible. The performance of the framework is successfully validated in experiments with a torque-controlled quadrupedal robot for generating dynamic motions.

Bio-Inspired Gait Transitions for Quadruped Locomotion

“…With the reference motions and forces from the motion planner a whole-body hierarchical inverse dynamics controller [4], accounting for system dynamics, is needed to compute joint torque commands. It formulates all robot tasks as affine functions generalised accelerations and external generalised forces, and defines strict priorities and the importance of weighting of each task within a hierarchy.…”

“…The stored gaits can vary from slow to highly dynamic, thereby necessitating a robust control framework for their stable execution in quadruped robots. State-ofthe-art frameworks typically employ model predictive control (MPC) for online trajectory optimisation to enhance stability [3], and a whole-body controller (WBC) for maintaining stable contact forces [4]. These strategies have proven successful in achieving highly dynamic locomotion.…”

High Utility Teleoperation Framework for Legged Manipulators Through Leveraging Whole-Body Control

“…CoM trajectory planners see frequent use for quadrupedal robot locomotion, such as in [30,31]. Therefore, in order to allow this WBC to be compatible with these planners, a CoM tracking task is included.…”

Gait generation for real-time quadruped locomotion

“…Current state-of-the-art legged robotic platforms in the literature focus on high-speed locomotion with dynamic manoeuvres [1,2,3], exemplified by platforms like Boston Dynamics' Spot and Agility Robotics' Digit. These platforms are capable of running [4], jumping [5], and traversing stairs [6], finding applications in mapping and industrial inspection [7,8].…”

“…In these environments, where fast locomotion and agility are not a priority, mechanical design complexity and cost can be reduced while improving durability. However, most gait generation techniques in the literature remain complex and require powerful processors [1]. Our focus is on computationally inexpensive gait generation methods adaptable in real-time to the changing terrain.…”