Active stereo vision for robot guidance Principal investigators:- Dr John Pretlove and Dr Nongji Chen Pictured left is the Vice-Chancellor of the University, Prof. Patrick Dowling, with the prototype (phase 1) stereo head developed by the MSRR Group.

Active vision systems seek to dynamically and intelligently gather selective scene information. It is a distinctly active problem which requires probing and exploring of the entire visual field for the information that is salient to the current task. In the MSRR group there are several activities which are concerned with Active Machine Vision Systems, and we have the experience of building several high performance active stereo vision systems and their associated controllers.

A work-programme, completed way back in 1994, applied active machine vision to the problem of overcoming the uncertainties in a robotic-based workcell. A mechatronic, light-weight eye-in-hand sensor was designed and built to be capable of multi-resolution image processing. The system allows real-time adaptive control of robot motion. A photograph of the sensor is shown in here.

The original stereo head's primary function was to provide intelligent sensory information so that it could accurately guide the robot tool to a known object at an unspecified location and orientation within the robot workcell. Once there, the robot could perform a variety of functions such as assembly, pick and place, bin-picking, visual tracking and interception of objects on a conveyor system, inspection and 3D gauging. An animated GIF (354kbytes) showing the head mounted on a Puma 560 arm and performing 2D tracking of a shape in real time is can be viewed here, and another (304kbytes) showing 3D tracking (following stereo camera calibration) can be viewed here.

Following the work above, a much larger structure, termed GETAFIX, was then built for exploratory lab work by our neighbours in the VSSP Group at the University. This is a thirteen degree of freedom system with fully controllable cameras, independent vergence, collective pan and tilt and automatic zoom adjustment. This system is based on stepper motor design and is therefore exhibits a fairly slow response time and poor acceleration characteristics but is a very useful laboratory tool. It was not designed for robotic mounting or mobile work.

The next piece of work featured a collaboration with DERA in producing a robotic stereo head capable of mimicking the actions of a human operator for remote telepresence operations. An animation (181kbytes) of this head in action whilst slaved to a Polhemus sensor mounted on a HMD can be viewed here.

The most recent stereo vision system is an advance on our previous systems, being extremely small and designed to mount on a small laboratory mobile vehicle. It has been primarily designed as a robust remote telepresence system. Click here for a picture of the latest (scarlet painted !) head alongside the original system.

Further information :-

Dr John Pretlove
email: john.pretlove@no.abb.com

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Last change: April 2000