Urban Search and Rescue (USAR) Robot

Project

The goal of the project is to successfully simulate an already existing USAR robot in software. The robot is split into three cars with treads on top and bottom. Linking the cars together is a special joint with 2 degrees of freedom. The joint is completely passive is the side to side degree of freedom. The joint employs a spring and motor mechanism in the up-down degree of freedom. This allows the cars to conform to the terrain while also allowing a car to pick up the car in front of it. For the simulation I have been using the Open Dynamics Engine (ODE) Physics SDK. I have been able to successfully model a robot with three cars and two wheels on each side. The link between the robots works what I think is appropriately. Because the robot has treads however, I would like to add a third wheel to the side to simulate closer to the traction of treads. When adding the third wheel to a side the third car falls through the ground. This is a problem. One other problem worth mentioning is the stretchiness of the joints between the robots. The joint don't seem to be too fixed to the place they are attached. I have tried adjusting the CFM and ERP parameters, but haven't found the right mix. Any suggestions are welcome. Respond to Jeffrey Pinney. Here is the code for three of the different builds I have. A lot of the code follows the format of the test buggy code and the comments are not very good right now. I realize I should be shot for posting such horribly formed code, but I am in a pinch and I will hopefully clean it up and add to this post soon.

linkedupper_1.5.cpp - this is a build with the robot working fine but only two cars a side.

the robot resting

second car picking the first one up

the third car picking the second car up

linkedupper_1.7.cpp - three wheels a side with the third car going through the ground

the only thing keeping the car where it is, is the link between it and the second car

linkedupper_1.8.cpp - three wheels a side with the link removed so the third car just goes away

the link is removed, the third car disappeared right through the ground.

Any ideas or responses can be sent to Jeffrey Pinney. Thank you.