Hongda Pan

Precision Evaluation of Three-dimensional Feature Points Measurement by Binocular Vision

Binocular-pair images obtained from two cameras can be used to calculate the three-dimensional (3D) world coordinate of a feature point. However, to apply this method, measurement accuracy of binocular vision depends on some structure factors. This paper presents an experimental study of measurement distance, baseline distance, and baseline direction. Their effects on camera reconstruction accuracy are investigated. The testing set for the binocular model consists of a series of feature points in stereo-pair images and corresponding 3D world coordinates. This paper discusses a method to increase the baseline distance of two cameras for enhancing the accuracy of a binocular vision system. Moreover, there is an inflexion point of the value and distribution of measurement errors when the baseline distance is increased. The accuracy benefit from increasing the baseline distance is not obvious, since the baseline distance exceeds 1000 mm in this experiment. Furthermore, it is observed that the direction errors deduced from the set-up are lower when the main measurement direction is similar to the baseline direction.

A Novel Method for Wheel Rim Recognition

The recognition of the wheel rim is a crucial area for vehicle safety. We present a novel recognition method for the detection of wheel rim whose projective curve is an ellipse. An image preprocessing method including the Otsu algorithm to binary the gray image, removing spurious areas and region filling algorithm is introduced to segment the rim area correctly. Then the ellipse rim region is considered as a 2D sheet and the centroid coordinate of the ellipse region is identified by the formula of calculating mass center. At last, all the five parameters to construct the ellipse of wheel rim are obtained according to the geometrical property that the optimum vertex on the semiaxis is the point on the edge of ellipse whose distance between the centroid and the point is maximum or minimum. The experimental results show that the proposed method recognizes the wheel rim efficiently and precisely.

Measurement Performance Assessment: Dynamic Calibration Compared with Static Calibration Method for Roller Tester of Vehicle Brake Force

The measurement performance of the roller tester for the vehicle brake force is evaluated by both proposed dynamic calibration and traditional static calibration to find an effective way for ensuring the vehicle safety. Three static parameters, brake force error of a single bench, difference of the left and right benches, and measurement repeatability, are verified to be eligible in the experiments. However, the experimental results of the dynamic calibration prove that the same brake tester fails on the repeatability with a 10.4% error. The dynamic calibration method improves the measurement performance of the brake tester in practical applications.

The model and simulation analysis for the detection performance of brake tester

In this paper, a model of the roller brake tester is established to simulate the braking process when the wheels are tested on the rollers by Simulink. The real vehicle experiments are used to verify the simulation model. The simulation and experiment results show that the tester will not be influenced by other system structure dimensions when the installation angle is 32°-35° and the experimental results can help to realize the largest friction force.