Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!munnari.oz.au!uniwa!bilby.cs.uwa.oz.au!bilby!chrisp From: chrisp@bilby.cs.uwa.oz.au (Chris Pudney) Newsgroups: comp.robotics Subject: Proximity Sensors (again) Message-ID: Date: 26 Apr 91 08:45:01 GMT Organization: Dept. Computer Science, University of Western Australia. Lines: 41 G'day, I am working on a collision prevention project for our U.M.I. RTX robot arm. The arm has a reach of approximately 1.3m (~4.25ft) and a stopping distance of the order of a few centimetres (a few / 2.54 inches). Collisions will be prevented by sensors mounted on the arm that alert the controller when an obstacle is approaching the arm's stopping distance. The controller then halts the arm before collision with the obstacle can occur. I have considered using ultra-sonic sensors (such as the Polaroid sensor), but have read that this sensor behaves poorly for distances less than 30cm (~1ft). Active damping of the transducer can improve performance for such distances. Also in order to completely protect the RTX arm would require a number of sensors. They cost about $500 each here. Alternatively, I could use I-R sensors. These sensors operate well at distances under 30cm (~1ft) and are less prone to specular reflections than ultra-sonic sensors. They are however affected by surface colour and have a fairly narrow beam width (so I may literally have to plaster the arm with sensors to completely protect it). Again cost may be a limiting factor here. I would appreciate any information (operating ranges, prices, problems etc.) you have that would help me choose a sensor suitable for the task outlined above. Stories of proximity sensors you have used are also welcome. AtDhVaAnNkCsE. -------------------------------------------------------------------------------- Chris Pudney Department of Computer Science, PHONE: (local: 09) (int'l: +61 9) 380 3455 University of Western Australia, Nedlands, Western AUSTRALIA, 6009. FAX: (local: 09) (int'l: +61 9) 382 1688 E-MAIL: chrisp@cs.uwa.oz.au -- -------------------------------------------------------------------------------- Chris Pudney Department of Computer Science, PHONE: (local: 09) (int'l: +61 9) 380 3455