A miniature bio-inspired position sensing device for the control of micro-aerial robots

Here we present an example of a novel bio-inspired active vision system with a vibrating eye that can rotate freely by means of a miniature rotary piezo motor. Active micro-vibrations were applied to the eye by using an innovative micro-mechanism based on a tiny stepper motor. The hyperacuity of this inexpensive position-sensing device, which results from the active micro-vibrations, makes it capable of measuring the angular position of a contrasting edge. Among the many miniature rotary actuators available, piezomotors are often used when small size, low mass, great accuracy and high dynamics are required. The newly off-the-shelf miniature ultrasonic piezomotor presented in this study along with its position servo control system is supplied ready-integrated into a printed circuit board (PCB). The PCB Piezomotor (or PCBMotor) has many advantages, such as high torque (it requires no reducer), fast dynamics (the mechanical time constant is 3 ms), a low mass (1 gram) and a compact size (it is only 20 mm in diameter and 2.6 mm thick). The results of the tests conducted show that the performances of the PCBmotor connected to a custom-made miniature electronic driver make it a good alternative to the actuators classically used in robotic applications. In addition we present a simple visual processing, implemented onto a tiny microcontroller, composed of simple linear filtering and arithmetic operations. We show that our visual scanning sensor is a genuine position sensing device able to measure the relative angular position of a visual object with only two pixels and very few computational resources.