Development of a Miniature Underactuated Tripod Robot Inspired by Penguin Waddling Gait

Mobile robots utilizing vibration direct drive by eccentric motors have the advantages of compact structure, easy control, and low driving voltage, which facilitate miniaturization, lightweight design, and integration. Inspired by the waddling gait of penguins, this work proposes a vibration direct drive miniature tripod robot powered by a single eccentric motor. This robot demonstrates excellent load capacity and low transport costs. Notably, the waddling motion of the robot is achieved by alternately exciting the eccentric motor with positive and negative pulse-width modulation (PWM) signals. An unbalanced force is generated by using the integrated onboard power supply and control system as the eccentric mass of the robot. The structure design and electrical design are conducted, the working principle is analyzed, and a robot prototype is fabricated. The prototype weighs 12 g and has dimensions of 33 mm × 29 mm × 23 mm. Experimental results demonstrate that it can bear a maximum load of 143 g, which is 11.92 times its self-weight, and achieve a minimum cost of transport of 27.98. This work presents a new approach to research vibration direct drive underactuated miniature robots actuated by a single eccentric motor.