SimoBot: An Underactuated Miniature Robot Driven by a Single Motor

A simple-structured, low-cost miniature robot is highly desired for swarm robotics research. In this article, we designed an underactuated miniature robot using only one motor, named as SimoBot, to save space, cost, weight, and energy consumption. Since it has only one motor but needs to travel on the 2-D ground, the design, moving mechanism, and control are all challenging. We conceived a movement strategy based on the interplaying between the centrifugal force and swinging motion of the robot to generate translation and rotation on the ground and finally follow various arbitrary paths. This robot has only five simple components—a vibration motor, a button cell, a microcontroller board, four-pin legs (one of which is shorter than the others), and sensors. This article built the kinematics and kinetics models and analyzed and optimized the parameters. The prototype weighs only 4.76 g, costs 4.7 dollars, and is 20 mm in diameter and 18 mm in height. It can run as fast as 40 mm/s. Its cost of transportation is only 55, smaller than most miniature robots with onboard power and insects. By modulating voltage polarities on the motor and the periods, we demonstrated the controllability of SimoBot by the movement along a straight line, a circle, an “S” curve, and more arbitrary trajectories.