Dynamic analysis of feeding drive mechanism in planetary soil automatic drilling sampler

Abstract

It is presented in this paper that a novel soil drilling sampler which can be used to drill deeply automatically in the planetary soil. There are three transmission routes of motion in the drilling sampler: rotating drive mechanism and feeding drive mechanism are used to generate the rotary and axial movement of the driller respectively while impacting drive mechanism is used to assist drilling the hard substance. Drilling sampler has two control modes: constant feeding velocity mode and constant feeding force mode. A detailed dynamic model of feeding drive mechanism is established by using the lumped parameter method. It is shown from the solution of dynamic equations that in constant feeding velocity mode impact can be aroused in the motor and transmissions of feeding drive mechanism on the moment of load force mutation, while the stochastic variation of load force can make the moments/forces in mechanism fluctuate more seriously. In constant feeding force mode, startup of impacting function would make the bit impose periodic impact force on drilling object, and the amplitude of that impact force is larger than sum of the force imposed by bit on drilling object with impacting drive mechanism off and amplitude of impact force imposed by impacting drive mechanism on drive shaft, that can be thought that the drive shaft and driller have transmission amplification effect to the impact force. Works presented in this paper also provides theories for the design of feeding drive mechanism in drilling sampler.