Correction Algorithm of Sampling Effect and Its Application

The sampling effect of the imaging acquisition device is long considered to be a modulation process of the input signal, introducing additional error into the signal acquisition process. This paper proposes a correction algorithm for the modulation process that solves the sampling effect with high accuracy. We examine the algorithm with perfect continuous Gaussian images and selected digitized images, which indicate an accuracy increase of 106 for Gaussian images, 102 at 15 times of Shannon interpolation for digitized images, and 105 at 101 times of Shannon interpolation for digitized images. The accuracy limit of the Gaussian image comes from the truncation error, while the accuracy limit of the digitized images comes from their finite resolution, which can be improved by increasing the time of Shannon interpolation.

Field Distortion Model Based on Fredholm Integral

Field distortion is widespread in imaging systems. If it cannot be measured and corrected well, it will affect the accuracy of photogrammetry. To this end, we proposed a general field distortion model based on Fredholm integration, which uses a reconstructed high-resolution reference point spread function (PSF) and two sets of 4-variable polynomials to describe an imaging system. The model includes the point-to-point positional distortion from the object space to the image space and the deformation of the PSF so that we can measure an actual field distortion with arbitrary accuracy. We also derived the formula required for correcting the sampling effect of the image sensor. Through numerical simulation, we verify the effectiveness of the model and reconstruction algorithm. This model will have potential application in high-precision image calibration, photogrammetry and astrometry.

Intelligent Tire-Based Slip Ratio Estimation Using Different Machine Learning Algorithms

Estimation of the longitudinal slip ratio of tires is important in boosting the control performance of the vehicle under driving and braking conditions. In this paper, the slip ratio is estimated using four machine learning algorithms (Neural Network, Gradient Boosting Machine, Random Forest and Support Vector Machine) based on the acceleration signals from the tri-axial MEMS accelerometers utilized in the intelligent tire system. The experimental data are collected through the MTS experimental platform. The corresponding acceleration signals within the tire contact patch are extracted after filtering to be used for the training the aforesaid machine learning algorithms. A comparison is provided between the implemented ML algorithms using a 10-fold CV. NRMS errors in the CV results indicate that NN has the highest accuracy in comparison with other techniques. The NRSM errors of NN, GBM, RF, and SVM are 2.59\%, 3.30\%, 4.21\%, and 5.34\%, respectively. Among these techniques, GBM has a more stable results as it has the smallest output variance. The present study with the fusion of intelligent tire system and machine learning algorithms paves the way for the accurate estimation of tire slip ratio, which is critical for the development of reliable vehicle control algorithms.

Composing photomosaic images using clustering based evolutionary programming

Photomosaic images are a type of images consisting of various tiny images. A complete form can be seen clearly by viewing it from a long distance. Small tiny images which replace blocks of the original image can be seen clearly by viewing it from a short distance. In the past, many algorithms have been proposed trying to automatically compose photomosaic images. Most of these algorithms are designed with greedy algorithms to match the blocks with the tiny images. To obtain a better visual sense and satisfy some commercial requirements, a constraint that a tiny image should not be repeatedly used many times is usually added. With the constraint, the photomosaic problem becomes a combinatorial optimization problem. Evolutionary algorithms imitating the process of natural selection are popular and powerful in combinatorial optimization problems. However, little work has been done on applying evolutionary algorithms to photomosaic problem. In this paper, we present an algorithm called clustering based evolutionary programming to deal with the problem. We give prior knowledge to the optimization algorithm which makes the optimization process converges faster. In our experiment, the proposed algorithm is compared with the state of the art algorithms and software. The results indicate that our algorithm performs the best.