Sunday, October 17, 2021

Dynamic Hybrid Filter for Vision-Based Pose Estimation of a Hexa Parallel Robot

One of the problems with industrial robots is their ability to accurately locate the pose of the end-effector. Over the years, many other solutions have been studied including static calibration and dynamic positioning. This paper presents a novel approach for the pose estimation of a Hexa parallel robot. The vision system uses three simple color feature points fixed on the surface of the end-effector to measure the pose of the robot. The Intel RealSense Camera D435i is used as a 3D measurement of feature points, which offers a cheap solution and high accuracy in positioning. Based on the constraint of three color feature points, the pose of the end-effector, including position and orientation, is determined. A dynamic hybrid filter is designed to correct the vision-based pose measurement. The complementary filter is used to eliminate the noise of image processing due to environmental light source interference. The unscented Kalman filter is designed to smooth out the pose estimation of the vision system based on the robot’s kinematic parameters. The combination of two filters in the same control scheme contributes to increased stability and improved accuracy of the robot’s positioning. The simulation, experiment, and comparison demonstrate the effectiveness and feasibility of the proposed method.