An Efficient Paradigm for Feasibility Guarantees in Legged Locomotion

TL;DR

This paper introduces an efficient method for designing feasible CoM and body trajectories in legged robots, ensuring dynamic balance and kinematic limits, validated through simulations and experiments on HyQ and Aliengo robots.

Contribution

It presents a generalized feasible region formulation that guarantees dynamic balance and kinematic constraints, along with a planning strategy for legged locomotion.

Findings

Validated on HyQ and Aliengo robots

Achieved feasible trajectories with dynamic balance guarantees

Demonstrated efficiency of the planning strategy

Abstract

Developing feasible body trajectories for legged systems on arbitrary terrains is a challenging task. In this paper, we present a paradigm that allows to design feasible Center of Mass (CoM) and body trajectories in an efficient manner. In our previous work [1], we introduced the notion of the 2D feasible region, where static balance and the satisfaction of joint torque limits were guaranteed, whenever the projection of the CoM lied inside the proposed admissible region. In this work we propose a general formulation of the improved feasible region that guarantees dynamic balance alongside the satisfaction of both joint-torque and kinematic limits in an efficient manner. To incorporate the feasibility of the kinematic limits, we introduce an algorithm that computes the reachable region of the CoM. Furthermore, we propose an efficient planning strategy that utilizes the improved feasible region to design feasible CoM and body orientation trajectories. Finally, we validate the capabilities of the improved feasible region and the effectiveness of the proposed planning strategy, using simulations and experiments on the 90 kg Hydraulically actuated Quadruped (HyQ) and the 21 kg Aliengo robots.