A real-time vision-based 3D motion estimation system for positioning and trajectory following

The authors present a real-time vision-based system for automatic positioning and trajectory following, based on a direct method for 3D motion estimation. The spatio-temporal derivatives of the image function, calculated from time-varying imagery, are used to directly calculate the motion and position of the camera. For demonstration, they have implemented the system on a one-degree-of freedom thruster operating in a laboratory water tank. The estimated position information is communicated to the control system, a PID controller, in order to generate the appropriate signal to correct the thruster system´s position. The performance of the vision system is demonstrated in selected experiments by comparing results with the data from an optical encoder position sensor