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

Soft robotic actuators and their inherent compliance can simplify the design of controllers when operating in contact-rich environments. With such structures we can accomplish high-impact, dynamic, and contact-rich tasks that would be difficult using conventional rigid robots which might either break the robot or the object without careful modeling and design of high bandwidth controllers. In order to explore the benefits of structural passive compliance and exploit them effectively, we present a prototype robotic torso named Baloo, designed with a hybrid rigid-soft methodology, incorporating both adaptability from soft components and strength from rigid components. Baloo consists of two meter-long, pneumatically-driven soft robot arms mounted on a rigid torso and driven vertically by a linear actuator. We explore some challenges inherent in controlling this type of robot and build on previous work with rigid robots to develop a joint-level neural-network adaptive controller to enable high performance tracking of highly nonlinear, time-varying soft robot dynamics. We also demonstrate a promising use case for the platform with several hardware experiments performing whole-body manipulation with large, heavy, and unwieldy objects. A video of our results can be viewed at https://youtu.be/eTUvBEVGKXY.