Automatic elasticity tuning of industrial robot manipulators

We present a method for automatic elasticity tuning of industrial robot manipulators. The main contributions of the work are: a) The parameters of a mechanical mass-spring-damper equivalent of any order are solved given, only partial state information (motor encoder position and motor torque). b) The method is fully automatic with no operator input and can easily be applied in the field to update the dynamic model parameters. The ability to automatically update the elasticity parameters is particularly useful when the robot operators mount flexible tooling or equipment on the robot arms. c) The method separates friction and elasticity identification. d) The method is demonstrated on an industrial ABB robot. e) We combine an important result from the vibration literature (Yam and Elhay, 1996), with the solution of inverse eigenvalue problems (Gladwell, 1986). To our knowledge, this is the first time that these methods have been combined and applied to the identification of flexible robot manipulators. The main advantage of the method compared to other identification methods is the fact that only motor encoder position and motor torque are required to identify the springs, masses and dampers of an Nth order system