= Tilt and Pan Platform =
http://www.robotgroup.net/eric/TiltPan/P7312162.JPG GlennCurrie and EricLundquist of the Robot Group are working with [http://www.austinrobot.com Austin Robot Technology] to provide a large tilt/pan platform.  This platform will be mounted on top of the DARPA Grand Challenge vehicle and will carry one pair of high resolution video cameras and a laser scanner.  

== Frame ==
http://www.robotgroup.net/eric/TiltPan/P7312168.JPG The entire frame is constructed from one inch square steel.  This makes the frame very rigid, very strong and very durable. Here you can see the base, pan (with drive gear), and the tilt section all laid out.

== Pan ==
The ability to pan the cameras is required in order to be able to navigate around tight or hairpin turns. The pan mechanism is built from a go-kart hub that came off of a robot drive train owned by GlennCurrie.  This provides very sturdy and very smooth ball bearing motion.  The chain will be driven from a Everest and Jennings wheelchair motor also scavanged from the robot drive train.

== Tilt ==
The tilt mechanism will allow flexibility is choosing the optimum viewing angle with respect to the ground.  Tilt is driven by a heavy duty linear actuator [http://www.powerdrives.com/electrak/electrake150.htm Electrak] that was provided by BillCraig.

= History =

http://www.robotgroup.net/eric/TiltPan/P7092144.JPG July 9, 2005. Initially, we tried using the [http://www.solutions-cubed.com/solutions%20cubed/MMC2003.htm Motor Mind C] controller from [http://www.solutions-cubed.com Solutions Cubed].  The nice thing about the controller is that it supports both rs-232 commands and radio/control servo style commands.  This is useful for testing.  Of course, because we already had some in stock was another big incentive.  Unfortunately, the main problem is that the linear actuators use 4 Amps and the Motor Mind C is only good for 2 Amps per channel.  Even with no load, the controller would quickly go into thermal shutdown mode.

http://www.robotgroup.net/eric/TiltPan/P7302157.JPG Closed Flat Position.  These are a couple of photos of the tilt portion of the tilt/pan unit.  The scissor mechanism was created from standard hinges from the hardware store.  The pin used on the hinge was ground off at one end and then hammered out.  The pin was replaced with a 1/4 hex head bolt that was long enough to go through the hinge and the push rod on the linear actuator.

http://www.robotgroup.net/eric/TiltPan/P7302158.JPG Open or Max Tilt Position.  Note that we will still need some sort of pivot hinge on the rear end of the actuator so that it can swing up/down.

July 30, 2005.  Our friends at [http://www.tecel.com Tecel] have agreed to provide high current H-Bridges in the form of their [http://www.tecel.com/d200 D200] motor controller.  In addition, they are providing a [http://www.tecel.com/p500 P500] 8052 based microcontroller to provide the command interface, for position data acquisition and to drive the motor controllers.  We had to go with the P500 because we needed the built-in A/D conversion capability, as well as, the RS-232 communication capability. 

http://www.robotgroup.net/eric/TiltPan/P7312167.JPG July 31, 2005. We got the main structure for the pan motor mount done today.  The tilt mechanism still needs some work.
  
http://www.robotgroup.net/eric/TiltPan/P8032170.JPG August 3, 2005 Worked on getting a smaller footprint prototype to work.  Here it is in the "closed" position.

http://www.robotgroup.net/eric/TiltPan/P8032171.JPG Prototype tilt mechanism on a test stand in the open (raised) position.

http://www.robotgroup.net/eric/TiltPan/P8132172.JPG August 13, 2005 The hinge idea just wasn't working out for the tilt mechanism.  Version 2 of the tilt mechanism was built with "Heavy Duty" strapping located in the section where they have various metal joiners for 2x4 construction like roofing joists, etc.  These metal bars are rather thick and sturdy with pre-drilled holes to be used to attach 2 2x4's together.  Metal stock is grossly overpriced at Lowes/Home Depot (over $3 per foot!) but since these were joinst materials, they were $1.43 for each 1 foot section.  A little work with the drill and as you can see, we now have a scissor mechanism.  With 2 sections, it is about 5 inches in height.

http://www.robotgroup.net/eric/TiltPan/P8132174.JPG Here you can see the scissor mechanism in the extended position.  With only 2 inches of throw on the linear actuator, the mechanism has extended it to approximately 8 inches of throw!