Electrostatic Brakes Enable Individual Joint Control of Underactuated, Highly Articulated Robots

TL;DR

This paper introduces a stackable electrostatic brake for robotic joints that is lightweight, power-efficient, and enables complex manipulation with fewer motors, mimicking biological muscle properties.

Contribution

The development of a novel electrostatic brake that matches muscle strength and weight, enabling underactuated, highly articulated robots with improved efficiency and dexterity.

Findings

Brake-equipped joint is four times lighter than electromechanical motors.

Robot with brakes can manipulate multiple objects simultaneously.

In-hand re-positioning is 45% faster with lower error using brakes.

Abstract

Highly articulated organisms serve as blueprints for incredibly dexterous mechanisms, but building similarly capable robotic counterparts has been hindered by the difficulties of developing electromechanical actuators with both the high strength and compactness of biological muscle. We develop a stackable electrostatic brake that has comparable specific tension and weight to that of muscles and integrate it into a robotic joint. Compared to electromechanical motors, our brake-equipped joint is four times lighter and one thousand times more power efficient while exerting similar holding torques. Our joint design enables a ten degree-of-freedom robot equipped with only one motor to manipulate multiple objects simultaneously. We also show that the use of brakes allows a two-fingered robot to perform in-hand re-positioning of an object 45% more quickly and with 53% lower positioning error than without brakes. Relative to fully actuated robots, our findings suggest that robots equipped with such electrostatic brakes will have lower weight, volume, and power consumption yet retain the ability to reach arbitrary joint configurations.