Stereo Vision System Module for Low-Cost FPGAs for Autonomous Mobile Robots

Stereo vision uses two adjacent cameras to create a 3D image of the world. A depth map can be created by comparing the offset of the corresponding pixels from the two cameras. However, for real-time stereo vision, the image data needs to be processed at a reasonable frame rate. Real-time stereo vision allows for mobile robots to more easily navigate terrain and interact with objects by providing both the images from the cameras and the depth of the objects. Fortunately, the image processing can be parallelized in order to increase the processing speed. Field-programmable gate arrays (FPGAs) are highly parallelizable and lend themselves well to this problem. This thesis presents a stereo vision module which uses the Sum of Absolute Differences (SAD) algorithm. The SAD algorithm uses regions of pixels called windows to compare pixels to find matching pairs for determining depth. Two implementations are presented that utilize the SAD algorithm differently. The first implementation uses a 9x9 window for comparison and is able to process 4 pixels simultaneously. The second implementation uses a 7x7 window and processes 2 pixels simultaneously, but parallelizes each SAD algorithm for faster processing. The 9x9 implementation creates a better depth image with less noise, but the 7x7 implementation processes images at a higher frame rate. It has been shown through simulation that the 9x9 and 7x7 are able to process an image size of 640x480 at a frame rate of 15.73 and 29.32, respectively

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum