六自由度平台动力学前馈柔顺控制研究

Research on Dynamics Feedforward Compliance Control of 6-DOF Platforms

与串联机器人相比,六自由度平台具有刚度高、承载能力大等优点,更适合于大型工件的装配。当机器人处于对接和装配状态时,机器人末端受到来自外部环境的力和力矩作用,对机器人的柔顺控制是执行任务的基础。提出了一种基于摩擦补偿的动力学前馈柔顺控制方法,首先建立Stewart平台的动力学模型,利用库仑摩擦模型和黏性摩擦模型对伺服电动缸的摩擦力进行估计,推导出包含摩擦力矩的运动学模型。设计了一种动力学前馈柔顺控制方法,无需在关节末端安装力传感器,平台受到外力时会顺应外力作用移动。最后实验结果表明,所提出的方法是一种经济、有效、可靠的方法,可以实现六自由度平台的柔顺控制。

Compared with the serial robot,the 6-DOF(degree of freedom)platform had the advantages of high stiffness and large load capacity,which was more suitable for the assembly of large workpieces.When the robot was in the docking and assembly states,the end of the robot was subjected to forces and moments from the external environments,and the compliant control of the robot was the basis for completing the tasks.A compliance control method was proposed based on friction compensation.A dynamics model of the Stewart platform was established.The friction forces of the servo electric cylinder was employed by means of the Coulomb and viscous friction model and the kinematics model including friction torque was derived.A dynamics feedforward compliance control method without using any force sensors at the end of the joints was designed.As the platform is subjected to external force,it will move in the direction of the external force.The experimental results show that the proposed unique methodology achieves an inexpensive and effective yet reliable alternative to be used for compliant control of 6-DOF platforms.