Inverse Model Command Shaper for a Flexible Gantry Robot

Abstract

Subject of this paper is an industrial gantry robot with elastic behavior. To suppress residual vibrations command shaping filters are widely used. These filters, however, Change the shape and duration of the originally commanded trajectory. Therefore, a command shaping filter is proposed which is based on the inverse model of the flexible robot dynamics. To that end, a planar dynamics model of the robot is derived which is suitable for control design. It captures the relevant dynamics of vibrations including the non-minimum Phase characteristics. Based on the inverse dynamics, a feedforward filter for vibration suppression is developed. The tracking error due to filter delay is reduced compared to other command shaping techniques. The non-minimum phase properties of the flexible dynamics are avoided by using a virtual reference Point for plant inversion. Experimental results show the effectiveness of the roposed Inverse Model Command Shaper compared to other types of filters tuned for vibration suppression.