Another approach to ensure motion of a robot through complex
environments with obstacles employs a motion planner. The
motion planning problem has been studied well in the literature;
we refer to [38] for a detailed survey. In the case of modular
robots with many DOFs and kinematic constraints, sampling-based
methods can be utilized [39]. Sampling-based methods solve the
task by random sampling of the robot’s configuration space. This
allows the creation of a roadmap of free configurations, in which
a feasible trajectory can be found. Widely-used sampling-based
planners are Probabilistic Roadmaps [40] and Rapidly Exploring
Random Trees (RRT) [41] and their variants. These methods have
been utilized in many applications [42–44], including modular
robotics [45–47] and reconfiguration planning [48].