Risley-prism-based visual tracing method for robot guidance.

A visual tracing model based on Risley prisms is proposed in this paper. Combined with the boresight adjusting technology and the visual detection technology, a new visual system is established. Placing Risley prisms in front of the camera, the field of view of the camera can be dynamically adjusted so that the imageable area of this camera is expanded greatly. Two real-time visual tracing strategies for dynamic targets are proposed, which effectively avoid the problems of target loss and tracking instability. The deviations between the reference trajectory generated by the manipulator and the actual trajectory detected by our visual system are measured. Experimental results show that the deviations are less than 1.5% in the 250 mm motion space of the manipulator. It is verified that the visual system can be used to guide robots with high precision, which provides a potential method for robot navigation.

Risley-prism-based tracking model for fast locating a target using imaging feedback.

Fast imaging tracking technology exhibits attractive application prospects in the emerging fields of target tracking and recognition. Smart and compact tracking model with fast and flexible tracking strategy can play a decisive role in improving system performance. In this paper, an effective imaging tracking model from a target to a rotation Risley prism pair embedded with a camera is derived by the beam vector propagation method. A boresight adjustment strategy using the inverse ray tracing and iterative refinement method is established to accomplish the function of fast locating a target. The influence of system parameters on boresight adjustment accuracy and even the dynamic characteristics of the tracking system are investigated to reveal the coupling mechanisms between prism rotation and imaging feedback. The root-mean-square tracking error is below 4.5 pixels by just once adjustment in the static target experiment, while the error in the dynamic experiment is below 8.5 pixels for a target moving at the speed of 50 mm/s, which validates the feasibility of the proposed method for fast imaging tracking applications.