Design and Evaluation of a Casting Valve Body Positioning System for Riser-Cutting Robots

Abstract

The current manual method for the removal of the casting riser for the valve body is characterized by low efficiency, and causes both environmental pollution and human health risks. To address these issues, an automatic method for the cutting of the casting riser using a stereo vision system and a manipulator is proposed in this work. The relative position of the valve casting and the end of the manipulator is determined via the position transformation of the valve casting, the manipulator end, and camera coordinate systems. The spatial motion trajectory of the manipulator is then planned to implement the automatic cutting of the pouring riser of the same valve casting with the same pose. The results of experiments show that the position and angle deviations of the repeated and random positioning accuracies of the visual system are within ±2 mm, ±0.5° and ±3 mm, ±1°, respectively. In the cutting test of the pouring riser, the maximum deviation between the actual and theoretical cutting trajectories is 3 mm. Therefore, the proposed method has good reliability and can meet the requirements of cutting accuracy.

Keywords

• casting riser cutting
• coordinate transformation
• valve casting
• visual servo