H∞ control design for positioning performance of gantry robots

When gantry robots are used for precision tasks such as circuit board assembly, structural vibrations limit the performance achievable from traditional controllers. This paper presents methods for modeling and controlling such robots, with the goal of simultaneously achieving fast and accurate positioning. Several joint position feedback model matching controllers are designed and compared, including a simple PD controller and three parametrized H_∞ controllers. One of the H_∞ controllers is shown to provide nearly optimal settling times with reduced structural vibration and reduced actuator requirements