Design and Control of a Vibratory Motile Robot

The ability for small-scale robots to move along directed pathways of locomotion is necessary in swarm and collective systems for navigation, coordination, and task execution. In this work, we introduce a minimal vibratory robot capable of directional control using only a single eccentric rotating mass (ERM) motor, a rotary encoder, and a low-resource microcontroller. We encode a software-defined asymmetry by modulating angular velocity as a function of motor rotation angle to enable arbitrary planar motion without physical design asymmetries. We derived a first-principles spring-mass model to predict locomotion behavior under varying motor inputs and validated the model with experimental results. A closed-loop controller enables consistent tracking of spatiotemporal angular velocity waveforms, allowing the robot to achieve directed motion. This control framework significantly expands motion capabilities while maintaining hardware simplicity, laying the foundation for scalable, coordinated behaviors in large groups of resource-constrained robots.