Session: 02-10-01: Variation Simulation and Tolerancing

Paper Number: 68437

Start Time: Friday, 11:25 AM

68437 - A Safety-Space-Based Approach to Inspection Path Planning for the Sheet Metal Assemblies 

Abstract: The inspection path planning of assembly dimensional deviations plays an important role in the measurement efficiency of the large free-form surfaces. In the process of path generation with the 5-axis coordinate measurement machine (CMM), the traditional computer-aided inspection planning methods need to consider the large calculation of collision detection and obstacle avoidance. Especially for the contacting measurement of the large complex free-form surfaces, instead of structure simplification with the determined bounding box, the complex surfaces such as the sheet metal assembly surfaces are always gridded with thousands of or even millions of point clouds for precise collision detection between the probe and the inspected measurement object. The huge calculation for collision-free trajectory generation is time-consuming and low-efficiency. Therefore, to address this problem, a safety-space-based modeling approach is proposed to generate a feasible collision-free path for a large number of key measurement point’s inspection. At first, based on the decomposition of the dynamic motion trajectory of the probe and the structural modeling of the inspected object, a continuous envelope space, i.e. safety space is constructed for the candidate path generation of the measurement probe. In the proposed planning strategy, the work of collision detection and avoidance is deleted. Then, a heuristic optimization algorithm is used to generate the feasible trajectory in the constructed safety space for all the measurement points. At last, an inspection path generation case of a car door assembly was used to evaluate the effectiveness of the proposed method. Results showed the calculation efficiency was improved to a great extent.

Purpose of this paper: The project source of this paper is from the computer-aided inspection planning (CAIP) requirement of the auto body manufacturing and measurement processes. For a new car model, the traditional assembly deviation inspection planning for the full auto body always consumes more than 10 working days because of the lack of the automatic CAIP software tool for the complicated sheet metal part surfaces. In practice, most of the commercial CAIP software is used for the inspection planning results verification, but not the wholely automatic trajectory generation process from the start. The main reason is how to get the obstacle avoidance trajectory when the collision problems occur in the original inspection path efficiently. Therefore, this paper proposes a new strategy to obtain a safety-space, which is generated based on collision-free constraints and also inspection standards. Then, in this safety-space, a new path generation method is proposed for the optimal trajectory with a short measurement time. An automatic path planning tool was developed for the sheet metal assembly inspection and applied in the auto body shops. This work was partly supported by the State Key Laboratory of Mechanical System and Vibration (Grant No. MSV202010) and partly supported by the Shanghai SAIC General Motors Corporation (Grant No. PS23038162).

Presenting Author: Chao An University of Shanghai for Science and Technology

Authors:

Yinhua Liu University of Shanghai for Science and Technology
Chao An University of Shanghai for Science and Technology
Zhenxia Duan University of Shanghai for Science and Technology