If a robot system can take various shapes, then it can play various roles, such as humanoid, dog robot, and robot arm. A modular robot is a robot system in which robots are configured using multiple modules, and it is possible to configure robots of other shapes by varying the combinations of the modules. In conventional modular robots, the shape is restricted by gravity, and configurable shapes are limited. In this study, we propose a gravity compensation modular robot to solve this problem. This paper describes the design and prototyping of the gravity compensation modular robot, and provides examples of robot shapes configured using the gravity compensation modules and motion experiments of the robots. In the experiments, there were motions that the robots could perform and could not perform. We considered the lack in the gravity compensation level and module rigidity as the main factor of the failures. This paper also discusses the solutions to these problems.
