eViper: A Scalable Platform for Untethered Modular Soft Robots

Soft robots present unique capabilities, but have been limited by the lack of scalable technologies for construction and the complexity of algorithms for efficient control and motion. These depend on soft-body dynamics, high-dimensional actuation patterns, and external/onboard forces. This paper presents scalable methods and platforms to study the impact of weight distribution and actuation patterns on fully untethered modular soft robots. An extendable Vibrating Intelligent Piezo-Electric Robot (eViper), together with an open-source Simulation Framework for Electroactive Robotic Sheet (SFERS) implemented in PyBullet, was developed as a platform to analyze the complex weight-locomotion interaction. By integrating power electronics, sensors, actuators, and batteries onboard, the eViper platform enables rapid design iteration and evaluation of different weight distribution and control strategies for the actuator arrays. The design supports both physics-based modeling and data-driven modeling via onboard automatic data-acquisition capabilities. We show that SFERS can provide useful guidelines for optimizing the weight distribution and actuation patterns of the eViper, thereby achieving maximum speed or minimum cost of transport (COT).

I. Introduction

Research on robots with rigid components has a long history. Designing and controlling soft robots for a variety of tasks - from crawling on surfaces to carrying different payloads - is just beginning to be understood [1], [2]. Soft robots are attractive because: (1) they are deformable and can closely mimic animal behavior; (2) they are soft and thus more collision-resilient than traditional rigid-body robots; (3) they can perform tasks that rigid robots cannot perform [3]–[10]. The actuators in a soft robot can be activated electrically, thermally, or pneumatically [11]. Many factors affect the locomotion of soft robots, including the actuation patterns of the actuators, the weight distribution across the soft robot body, and the capability of untethered operation. Some of the above demonstrations are tethered hence only consider the impact of weight distribution in the context of tethered operation. Some other designs have limited control degrees of freedom (DOF). Research on the energy efficiency, and actuation-locomotion co-design is still at the early stage [12].