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 mechanism 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 hydraulic 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 collective modular robot achieves desired motion tasks while keeping all normal contact forces of the connectors being lower-bound. The results are also explained in the supplementary video.