Design and Control of a Miniature Quadruped Rat-inspired Robot

Robot-rat interaction test is a promising way to characterize the animal sociality for biomedical application. However, currently developed robotic rats are mostly driven by wheels, resulting in limited movement agility. It is an arduous task to realize both the morphology and functionality of rat limbs within restricted dimension. In this specified scale, it is not only difficult to design efficient mechanism to achieve high-speed movement but also difficult to integrate many actuated joints to accomplish multiple motion modes. To address these problems, we modularly designed a miniature quadruped robot making full use of connecting rod mechanism to mimic rat limbs. To generate bio-inspired quadruped gait by using a compact control board, we developed a locomotion controller based on central pattern generators (CPG). Together with particle swarm optimization (PSO) algorithm, the stride frequency and length can be adjusted by parameters. Both simulation and experimental tests show that our quadruped rat-inspired robot is able to implement three motion modes. 1) Crouch-standing action: the robotic rat is able to stand up from initial state (kneeling action) without manual support. 2) Forward walking: the robot reaches a maximum speed of 10cm/s. 3) Turning action: the robotic rat has a small turning radius of 12 cm that is only half of its body length. The outperformance of this robotic rat show high promises in performing natural robot-rat interaction in future.