Steerable miniature ambulatory robot based on piezoelectric actuation with a caltrop-like structure

Conventional piezoelectric actuators or robots have advantages of miniature sizes, fast responses, good accelerations, and long stroke, but they are difficult to recover their movement after a sudden rollover or overturn. In order to achieve a consecutive motion in an abrupt environment, a steerable miniature ambulatory robot (SMAR) with a caltrop-like structure is proposed based on piezoelectric actuation. A kinematic model of the SMAR is developed to design the structure of the robot and to analyze the working principle. A preliminary prototype is fabricated to verify the working principle that it has a capacity of 2D motion, with the maximum speed of 320 mm s(-1) and the minimum turning radius of 40 mm when the drive voltage is 200 V (peak-peak value). In addition, a control strategy designed in a LabVIEW system which can refine the eigenvalues from complex motion trajectories, is presented for robust steering to a target in a short time, especially after a sudden rollover. Therefore, this SMAR can realize arbitrary and fast movements in a 2D task space, which is also appropriate for a dynamic environment, such as in a moving or rolling channel, and it can also step down with a smooth movement due to its special caltrop-like structure.