Abstract: [Objective] In order to detect the tiny defects of the edges of the bamboo slices, micro amplitude vibration of ultrasonic motor was utilized. The relationships between the micro amplitude vibration parameters of the ultrasonic motor and the size of the bamboo slices were studied. The device was designed to detect the change of the edge size of bamboo slices within 100 microns. It provides the theoretical basis for the on-line rapid detection of the production process.[Method] Using the converse piezoelectric effect of piezoelectric ceramics, elliptical motion in the stator of an ultrasonic motor drives the bamboo movement. The driving point is the edge of the bamboo slices. Under the normal pressure, sliding friction and wave number of different ultrasonic motors with fixed driving frequency of ultrasonic motor, analysis of the motion velocity of bamboo slices and the motion of the stator particle of the ultrasonic motor was analyzed by the stator kinetic equation. The movement of bamboo slices was analyzed by microscopic observation of the micromorphology of the bamboo slices.[Result] 1) The number of wave peaks of an ultrasonic motor driving bamboo is proportional to the driving force produced by an ultrasonic motor. With the change of the edge size of the bamboo slices, there is a gap between some stator driving particles and the bamboo slices when the bamboo slices are in contact with the stator. The number of wave peaks in a certain time point is reduced,Resulting in a decline in the speed of the bamboo motion. The number of wave peaks which drive the bamboo slices is reduced, which leads to the decline of the speed of the bamboo motion. 2) The normal pressure produced by the bamboo slices is evenly distributed on the wave peak driving point produced by the ultrasonic motor. When the size of the edge of the bamboo strip is reduced, the normal pressure is reduced. The driving force decreases, which reduces the speed of the bamboo motion. 3) Ultrasonic vibration produced by the stator of an ultrasonic motor produces ultrasonic friction reduction effect. The speed of the bamboo motion is reduces with the reduction of normal pressure. 4) Bamboo slices with error value from 0 to 50 microns were detected using the device for detecting the edge of bamboo. The relationship between the average speed of bamboo slices and the degree of bamboo defect is proportional. 5) When single bamboo was measured many times, its velocity fluctuated greatly. There are two reasons for the speed fluctuation. Firstly, the elastic modulus of different parts of bamboo is different, which leads to the change of the output force. Secondly, the micro morphology of the same piece of bamboo is very different. Under the microscope, the surface of the qualified bamboo slices has a micron level lack of edge phenomenon, which leads to the uneven contact surface of the bamboo edge driven by the ultrasonic motor. Therefore, the contact condition of the ultrasonic motor and the bamboo is changed. A change in the movement speed of bamboo slices caused by the change of contact surface condition.[Conclusion] The velocity of bamboo motion is proportional to the number of wave peaks of the ultrasonic motor that drive bamboo. The velocity of bamboo motion is reduced by the normal vibration of the ultrasonic motor. The increase of the pressure between the bamboo slices and the ultrasonic motor can increase the speed of the motion of the bamboo slices. The detection accuracy of the device for testing the lacing of bamboo slices is 48 microns. By measuring its speed, devices can distinguish the change of the defect size of the bamboo more than 48 microns. The size of bamboo slices cannot be measured accurately because of the large change in the size of the bamboo slice boundary size within the micron range.

Key words: side lace of bamboo, ultrasonic motor, micro amplitude vibration, ultrasonic vibration, detection