Drive Unit Mathematical Model of Robot Gripping Devices

Abstract

Today, the task of increasing the drive unit technical characteristics of robot gripping devices is relevant. In many respects, the drive motor and gear unit determine the quality of work of such modules, which can introduce additional elasticity, backlash and friction into the system. In turn, backlash and friction in the control loop decrease the speed and accuracy of the mechatronic module and can cause self-oscillations. However, significant progress in hardware performance of mechatronic and robotic systems makes it possible to more accurately estimate and control the force and torque state parameters in the output link and to carry out active algorithmic compensation for the effects of friction and elasticity.
 Such observers are usually based on detailed mathematical models and allows to implement force control without the use of special sensors, which is especially important in advanced gripping devices due to the requirements imposed on the mass-dimensional parameters of the product. Therefore, the purpose of this article is to make a general mathematical model of the robot drive unit with a rational relationship of complexity and accuracy. The models’ parameters should be easily identified from the constituent elements of passport data or the experiment results. The model should allow estimating the state parameters of mechanical transmission in real time; take into account the main friction effects. However, it should be simple enough for analytical conclusion and numerical modeling. As part of the article, various friction models are considered. On the basis of this analysis, a modified friction model is proposed. It makes possible to estimate the state parameters of mechanical transmission in real time. It is built into the general mathematical model of the mechatronic module. The results of mathematical simulation are close to experimental data. The considered drive unit mathematical model can be used to identify the state parameters of the mechatronic module in real time and implement force control based on estimation. In addition, the obtained model allows to conduct mathematical simulation of the robot taking into account the drive unit dynamics.