Whole-Body Trajectory Optimization for Robot Multimodal Locomotion

TL;DR

This paper introduces a unified whole-body trajectory optimization framework for multimodal robots, combining aerial and legged locomotion models to generate feasible trajectories validated on the iRonCub robot.

Contribution

It presents a novel trajectory optimization approach that integrates models for aerial and terrestrial locomotion within a single framework, enabling multimodal robot planning.

Findings

Successfully generates trajectories for both aerial and terrestrial modes.

Validates approach on the iRonCub humanoid robot.

Uses open-source ADAM library for optimization.

Abstract

The general problem of planning feasible trajectories for multimodal robots is still an open challenge. This paper presents a whole-body trajectory optimisation approach that addresses this challenge by combining methods and tools developed for aerial and legged robots. First, robot models that enable the presented whole-body trajectory optimisation framework are presented. The key model is the so-called robot centroidal momentum, the dynamics of which is directly related to the models of the robot actuation for aerial and terrestrial locomotion. Then, the paper presents how these models can be employed in an optimal control problem to generate either terrestrial or aerial locomotion trajectories with a unified approach. The optimisation problem considers robot kinematics, momentum, thrust forces and their bounds. The overall approach is validated using the multimodal robot iRonCub, a flying humanoid robot that expresses a degree of terrestrial and aerial locomotion. To solve the associated optimal trajectory generation problem, we employ ADAM, a custom-made open-source library that implements a collection of algorithms for calculating rigid-body dynamics using CasADi.