A low power laser rangefinder for autonomous robot applications

Autonomous robots require specific vision systems capable of providing accurate three-dimensional scene analysis. Direct time-of-flight laser rangefinders present themselves as an attractive alternative to other vision systems commonly employed in robotic vision systems, such as triangulation and ultrasound rangefinders, thanks to their superior radial and lateral accuracy. However, laser rangefinders present safety problems, due to the power level of the emitted beam, which condition their use in human environments. In the present work, the authors deal with the problem of safety, reducing the emitted power by employing different means to enhance receiver sensitivity. A first result of this work is presented in this paper, describing the development and preliminary experimental results of a direct detection laser rangefinder, which covers a maximum range of 7 metres with an emitted optical power of only 2 milliwatts. This prototype will be installed and tested on a RWI B21 mobile robot.