Versatile, Robust, and Explosive Locomotion with Rigid and Articulated Compliant Quadrupeds

2025-04-17

AI Summary

Achieving versatile, explosive, and robust locomotion for quadrupedal robots under dynamic uncertainties remains challenging. Method: This paper proposes a template-based modeling and hierarchical control framework integrating parallel compliant structures. It introduces a novel decoupled bipedal spring-loaded inverted pendulum (SLIP) template model—separating spring compliance from motor actuation—that enables singularity-free torso rotation representation for highly dynamic maneuvers including pronking, froggy jumping, and hop-turning. The approach encompasses bi-level trajectory optimization, linear singularity-free tracking control, reduced-order templated modeling, parallel compliant mechanism design, and hardware validation. Contribution/Results: Experiments demonstrate that the new compliant platform improves explosive maneuver performance by 25–30% over rigid platforms, significantly enhances disturbance rejection, and doubles the allowable support-surface height tolerance (100% improvement).

Technology Category

• Intelligent Robots: Manipulation
• Planning, Routing, and Scheduling: Replanning and Plan Repair
• Humans and AI: Human-Aware Planning and Behavior Prediction

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• User Modeling, Personalization and Recommendation: User modeling and simulation for interactive and conversational systems

Abstract

Achieving versatile and explosive motion with robustness against dynamic uncertainties is a challenging task. Introducing parallel compliance in quadrupedal design is deemed to enhance locomotion performance, which, however, makes the control task even harder. This work aims to address this challenge by proposing a general template model and establishing an efficient motion planning and control pipeline. To start, we propose a reduced-order template model-the dual-legged actuated spring-loaded inverted pendulum with trunk rotation-which explicitly models parallel compliance by decoupling spring effects from active motor actuation. With this template model, versatile acrobatic motions, such as pronking, froggy jumping, and hop-turn, are generated by a dual-layer trajectory optimization, where the singularity-free body rotation representation is taken into consideration. Integrated with a linear singularity-free tracking controller, enhanced quadrupedal locomotion is achieved. Comparisons with the existing template model reveal the improved accuracy and generalization of our model. Hardware experiments with a rigid quadruped and a newly designed compliant quadruped demonstrate that i) the template model enables generating versatile dynamic motion; ii) parallel elasticity enhances explosive motion. For example, the maximal pronking distance, hop-turn yaw angle, and froggy jumping distance increase at least by 25%, 15% and 25%, respectively; iii) parallel elasticity improves the robustness against dynamic uncertainties, including modelling errors and external disturbances. For example, the allowable support surface height variation increases by 100% for robust froggy jumping.

Problem

• Achieving versatile and explosive quadruped locomotion robustly
• Modeling parallel compliance in quadruped design for better performance
• Developing efficient motion planning and control for compliant quadrupeds

Innovation

• Dual-legged actuated spring-loaded inverted pendulum model
• Dual-layer trajectory optimization for acrobatic motions
• Linear singularity-free tracking controller integration