Baloo: A Large-Scale Hybrid Soft Robotic Torso for Whole-Arm Manipulation

TL;DR

Baloo is a large-scale hybrid soft-rigid robotic torso that demonstrates high payload capacity and effective whole-body manipulation in contact-rich environments, leveraging passive compliance for improved performance.

Contribution

We introduce Baloo, a novel hybrid soft-rigid robotic torso with high payload capacity and successful generalization in grasping diverse objects, showcasing advantages of soft actuators in manipulation.

Findings

Capable of lifting up to 19 kg payloads.

Achieved 100% success in grasping six diverse objects.

Demonstrated effective generalization with simple control strategies.

Abstract

Soft robotic actuators can simplify the design of controllers when operating in contact-rich environments. Importantly, their passive compliance fundamentally alters contact mechanics by smoothing impacts and distributing forces over large areas. By integrating soft actuators, we can perform high-impact, dynamic, and contact-rich tasks that are challenging or impossible for traditional rigid robots. In order to explore the benefits of passive structural compliance and learn to utilize it effectively, we present a prototype robotic torso named Baloo. Baloo's hybrid soft-rigid design incorporates both adaptability from soft components and strength from rigid components with two meter-long, pneumatic robot arms mounted on a rigid torso. The hybrid design is capable of lifting end effector payloads of up to 19 kg, far exceeding many hybrid robot designs. Such payloads are competitive with similar-sized rigid robots, but with a much higher strength-to-weight ratio. Through 30 physical whole-body grasping experiments, we also demonstrate how a simple control strategy can generalize for effective lifting across six challenging objects with diverse shapes, sizes, and weights. A 100% success rate across all objects--achieved with the simple control strategy--underscores the potential of our hybrid soft-rigid robot design for contact-rich, whole-body tasks.