Study On Driving Characteristics Of Flexible Soft Drive Mechanism

With the progress of science and manufacturing technology,the research of mechanism extends from rigid to flexible mechanism.Robot with Flexible mechanisms is inspired by animals,legged animals can walk on rough road,caterpillar crawl along irregular object.This paper is based on a flexible mechanism which has a nut body with rollers and a flexible shaft.New screw pair in the mechanism is similar with the ball screw pair,which uses spring and rollers to convert rotary motion to linear motion.Due to the flexibility of the spring,this mechanism can walk curve motion.Pipe robot with the mechanism get unstable bending during the motion of the curved pipeline,and it will cause the motor idling.Therefore,this paper aims at modeling the unstable bending and experiment validates for the situation of unstable bending.The specific contents are as follows:First,the combination shaft is analyzed and the structural size is designed.The combination shaft consists of a spring shaft and a slender shaft.Based on structure analysis,the compression stiffness and bending stiffness of the complicated spring shaft are solved.Then the stiffness of the slender shaft is solved during the bending motion.After that,by both consideration of the spring shaft and the slender shaft,the combination shaft modeling is established.In order to improve the contact area,the structural size is changed according to the force deformation of the spring shaft.In order to improve the stability of the combination shaft,the stiffness analysis of the combination shaft is performed.Secondly,the modeling of spring shaft for curve motion is studied.Distinct force of the spring shaft cause differences axis shape and eigenvalue buckling.Under small deflection assumption,the relation of displacement and strain can be derived,but the length of lateral deformation can not be derived in large deflection of the shaft.In the condition of large deflection,the whole length of the shaft is divided into small section.The small section of the shaft build up differential equation and modeling the whole shaft.Instead of iterive method,derivative method is used on solving of the shaft model.And the modeling of the shaft mechanism is established and the relation of the parameter is confirmed.Then,the motion of shaft mechanism and the transmission efficiency is studied.Since the curve motion of the shaft is different on the nut body mechanism and the fixed end,the lateral deformation will be changed according to the previous deformation.Therefore,by using derivative method to build up the curve motion of the shaft at the constant speed,the drive mechanism modeling is established.By calculating the deformation of the spring pitch,the power output and friction energy,the efficiency of the shaft mechanism is derived.Finally,the experiments of the modeling of shaft mechanism and transmission efficiency are discussed.The theoretical and the actual performance in curve motion are compared.The lateral deflection is compared under the spring flexible shaft and the combination flexible shaft.By performing transmission efficiency experiments,the actual result is measured and compared with theoretical result,and the efficiency under different loads,rotate speeds are measured.