Hyblock: Hardware Realization and Control of Modular Hydraulic Robots with Dowel Connectors

This paper presents the hardware design and development of Hyblock, a modular hydraulic robot for heavy-duty application such as construction. The robot is equipped with a simple docking mech- anism called a C-type expansion dowel and a novel hydraulic circuit MHSB that matches the modular structure. In this paper, we first report on the design of the robot hardware including the dowel and hy- draulic circuit, then present preliminary experiments on pressure-based torque control and docking control using proximal magnetic sensors. Next, we propose a framework for dynamic reconfiguration and task- space motion control built on the concept of dowel connectors. Simulation results demonstrate that a col- lective modular robot achieves desired motion tasks while keeping all normal contact forces of the connec- tors being lower-bound. The results are also explained in the supplementary video.