A Co-Design Framework for High-Performance Jumping of a Five-Bar Monoped with Actuator Optimization

TL;DR

This paper introduces a co-design framework for a five-bar monoped robot that jointly optimizes mechanical, actuator, and control parameters to enhance jumping performance and energy efficiency.

Contribution

It presents a novel two-stage optimization approach that includes actuator design in the co-optimization process for a closed-chain legged robot.

Findings

Jump distance improved by approximately 42%

Mechanical energy consumption reduced by 15.8%

Framework effectively identifies optimal design, actuator, and control parameters

Abstract

The performance of legged robots depends strongly on both mechanical design and control, motivating co-design approaches that jointly optimize these parameters. However, most existing co-design studies focus on optimizing link dimensions and transmission ratios while neglecting detailed actuator design, particularly motor and gearbox parameter optimization, and are largely limited to serial open-chain mechanisms. In this work, we present a co-design framework for a planar closed-chain five-bar monoped that jointly optimizes mechanical design, motor and gearbox parameters, and control parameters for dynamic jumping. The objective is to maximize jump distance while minimizing mechanical energy consumption. The framework uses a two-stage optimization approach, where actuator optimization generates a mapping from gear ratio to actuator mass, efficiency, and peak torque, which is then used in co-design optimization of the robot design and control using CMA-ES. Simulation results show an improvement of approximately 42% in jump distance and a 15.8% reduction in mechanical energy consumption compared to a nominal design, demonstrating the effectiveness of the proposed framework in identifying optimal design, actuator, and control parameters for high-performance and energy-efficient planar jumping.