Miniature Ultrasonic and Tactile Sensors for Dexterous Robot

Miniature ultrasonic and tactile sensors on Si substrate have been proposed, fabricated and characterized to detectobjects for a dexterous robot. The ultrasonic sensor consists of piezoelectric PZT thin film on a Pt/Ti/SiO2 and/or Sidiaphragm fabricated using a micromachining technique; the ultrasonic sensor detects the piezoelectric voltage asan ultrasonic wave. The sensitivity has been enhanced by improving the device structure, and the resonant frequencyin the array sensor has been equalized. Position detection has been carried out by using a sensor array with highsensitivity and uniform resonant frequency. The tactile sensor consists of four or three warped cantilevers which haveNiCr or Si:B+ piezoresistive layer for stress detection. Normal and shear stresses can be estimated by calculation usingresistance changes of the piezoresitive layers on the cantilevers. Gripping state has been identified by using the tactilesensor which is installed on finger of a robot hand, and friction of objects has been measured by slipping the sensor.