Approximating material area, volume,and velocity for belt conveyor systemapplications using 3D depth sensor technology

Abstract: Time of Flight (ToF) technology describes products or systems which measure distance by calculating the distance emitted light travels before bouncing off its surroundings and ending back up at the system. Since the early 2000s, many advancements in the area of ToF systems have been made leading to much use for the ToF variant LiDAR. Alternative technologies are on the rise, one of which is 3D ToF depth sensors. This report explores ToF depth sensor technology within the setting of belt conveyor system (BCS)applications. More specifically, methods for area, volumetric, and velocity approximation are explored and a comparison is also made against LiDAR. The aim of the report is split. One part aims to compare the accuracy of a ToF depth sensor to a 2D LiDAR scanner. The second one is to propose algorithms that, using only a ToF depth sensor, calculate the volume of material transported by a BCS and approximate the velocity at which said material is traveling. Methods for testing include strictly experimental setups in a controlled environment where both technologies were used to collect data on selected scenes. Results indicate that ToF depth sensors can achieve accuracy equivalent to LiDAR sensors. ToF depth sensors can resolve the volume of objects with relatively good results and algorithms that are not computationally complex. By implementing a proposed algorithm, the velocity of material traveling on a BCS was able to be approximated with up to 99% accuracy. However, effects of common sources of error are present in the result and hence have to be considered moving forward. Therefore, this report also highlights future improvements to establish a more robust methodology and reduce errors. The results can be used to improve current BCS, such as increased range of functionality, reduced costs, and raised quality control while also aiding in the enabling of Industry 4.0 implementation.