[ODE] AMotor query

Mark Williams mark at image-engine.com
Wed Nov 21 13:37:44 MST 2007

Mark Williams wrote:
>> Hi, I have an AMotor set up in 3-axis user mode with axes (1,0,0)   
>> (0,1,0)   (0,0,1) locked to the global frame. On all 3 axes, FMax is set 
>> to dInfinity, Vel is set to zero, and ERP is set to 1.0. This motor is 
>> then connected between a body and the static world. If I add any contact 
>> joints to the body, then I see a torque being applied and the body gains 
>> angular velocity. I was under the impression that motors 'look ahead' 
>> and so with the parameters I have set it should be almost impossible to 
>> rotate the body. Am I misunderstanding how motors are implemented?

I'm still investigating this but haven't got very far. What I'm trying 
to do is create immovable geoms by adding an LMotor and an AMotor, both 
trying to bring the linear and angular velocities back to zero with 
whatever force is necessary. I know the "correct" way to create geoms 
that don't respond to collision is to not give them a body, but then if 
those geoms are animated in any way then the contact joints have no 
knowledge of their velocity, giving an incorrect response. Is there any 
other way I can get the velocity information across if the motor 
approach is not going to work?


More information about the ODE mailing list