MMDL researchers have developed high precision piezomotors that operate in the millimeter regime, micrometer regime and nanometer regime. Currently there is no piezoelectric motor that is capable of having accuracy within 20nm, adequate speed and stiffness. The piezoelectric motor is the most commonly used smart material motor in the industry. Optimal motor design is demanded in many fields of industries such as metrology, biomedical research, MEMS and semi-conductor fabrication.
Currently there is no piezoelectric motor that is capable of having accuracy within 20nm, adequate speed and stiffness. The piezoelectric motor is the most commonly used smart material motor in the industry. Varieties of designs are available such as discontinuous motors (inchworm, caterpillar and walking) and ultrasonic motors (traveling wave, elliptical push, pi-shaped, and nanomotor).The MMDL motors are based on the inchworm principle and typically integrate three piezoceramic actuators inside a mechanical frame. Basic working principles of these motors as well as actual prototypes are shown. Optimal motor design is demanded in many fields of industries such as metrology, biomedical research, MEMS and semi-conductor fabrication.
The inchworm motor uses two clamps and an extension actuator to mimic inchworm movement. The movement of the slide is due to the force exerted by the motor clamp. This force is perpendicular to the axis of motion. Therefore the force applied has to be large enough to avoid slippage upon contact. The motor clamp moves in the same direction as the slide. Therefore if there is no slippage (sufficient friction) upon contact between the clamp and slide, the result is desired movement of the slide. The most advanced inchworm motor, developed by University of Toronto, shows improved performance (8mm/s and 20nm accuracy in nano regime). The focus of this project is a finding a better signal control algorithm or a better mechanical system that can reduce inaccuracy effects while not compromising the motor’s advantages.
MMDL researchers have also developed technology to overcome hyseresis and drift in piezoceramics actuators. The real-time compensation technology leads to high accuracy actuators operating over a wide dynamic range. Real-time open and closed loop hysteresis compensation schemes were implemented leading to high accuracy positioning using piezoceramics. The accuracy achieved is in the order of 10 nm over a bandwidth of 500 Hz.