Area of acceptance for 3D self-aligning robotic connectors: Concepts, metrics, and designs

Alignment of module connectors is a crucial component of self-reconfiguration in modular robotics. Accomplishing this process using passive mechanical geometry saves resources such as space and power for the modular robot. We present concepts for evaluation of these geometries as well as a new 3D geometry, the 3D X-Face. For comparing different connectors independent of the rest of the robot, figures of merit are presented which are based on the ability for connectors to mate in the presence of position and orientation errors (offsets). Figures of merit for many current connectors are presented. The 3D X-Face alignment behavior is simulated in Gazebo over several sets of initial conditions to estimate the full area of acceptance, and the connector is tested on a CKBot robotic platform. For the situation without rotation, results indicate a 27% improvement over current gendered connectors and a 467% over ungendered connectors. The 3D X-Face is further simulated over a full five-dimensional set and metrics are estimated on that set.