Trade-Offs in Exploiting Body Morphology for Control: from Simple Bodies and Model-Based Control to Complex Bodies with Model-Free Distributed Control Schemes

TL;DR

This paper discusses the advantages and challenges of designing robot bodies with various morphologies, emphasizing a dynamical systems approach and comparing simple versus complex or soft bodies for control, including model-based and model-free strategies.

Contribution

It advocates for a dynamical systems perspective on morphology control trade-offs and critically reviews simple and complex body designs, including soft bodies and control schemes.

Findings

Complex bodies can offload control computation through morphological computation.

Model-based control feasibility varies with morphology complexity.

Soft bodies offer potential but pose modeling and control challenges.

Abstract

Tailoring the design of robot bodies for control purposes is implicitly performed by engineers, however, a methodology or set of tools is largely absent and optimization of morphology (shape, material properties of robot bodies, etc.) is lagging behind the development of controllers. This has become even more prominent with the advent of compliant, deformable or "soft" bodies. These carry substantial potential regarding their exploitation for control---sometimes referred to as "morphological computation" in the sense of offloading computation needed for control to the body. Here, we will argue in favor of a dynamical systems rather than computational perspective on the problem. Then, we will look at the pros and cons of simple vs. complex bodies, critically reviewing the attractive notion of "soft" bodies automatically taking over control tasks. We will address another key dimension of the design space---whether model-based control should be used and to what extent it is feasible to develop faithful models for different morphologies.