Relative Distance Estimation for Indoor Multi-Robot Control Using Monocular Digital Camera

Abstract

Distance measurement methodologies based on the digital camera usually require extensive calibration routines, some are even derived from complicated image processing algorithms resulting in low picture frame rates. Particularly, in a dynamic camera system, due to the unpredictability of intrinsic and extrinsic parameters, the reliable measuring results are highly dependent on the accuracy of extra sensors. In this paper, a simple algorithm for relative distance estimation is proposed for multi-robot control with a monocular digital camera. Reasonable accuracy is achieved by judging the 2D perspective projection image ratio (PPIR) of robots' labels on a TFT-LCD (Thin Film Transistor-Liquid Crystal Display) monitor without any additional sensory cost and complicated calibration effort. Further, the algorithm does not contain any trigonometric functions so that it can be easily implemented on an embedded system using the field programmable gate array (FPGA) technology.