Any way to disable Physx Engine?


  • Hi Taylor:
       I want to build a pure kinematics articulated arm robot.
       As I think , there are two ways: disable Physx Engine or setting the spring property of joint to zero.
       I don't know how to execute the first way , the second way will cause the system unstable.
       Any suggestion?
    Monday, February 16, 2009 11:35 AM


All replies

  • This question should probably be in the Simulation forum. I will move it once you respond.

    I'm not sure what you mean by a pure kinematics arm. Arms composed of joints follow the usual forward / inverse kinematics.

    If you disable Physx, you won't get any simulation.

    Maybe you can explain what you are trying to do?



    Monday, February 16, 2009 5:36 PM
  • I have proposed this question in simulation forum for a month,No answer I propose here.
     I have built the same kinematics articulated robot model : Puma560 .  In MRDS and Matlab robotics toolbox.
       However, I found there was 5 percent difference between them ,about  0.1 to 3 meters.As I think the problem is below:
      (1)  In MRDS Kinematics simulation, We set the angle of joints in "update" of each  frame  >  then Physx Engine will begin Computation for about 1/60 second. and we read the position of the last joint in "update" of  the next frame . so it is not a pure kinematics has been processd by Physx.
             however, in Matlab it is a pure kinematics model , given angles produce end effector position. no consideration of dynamics such as gravity or other things.
      (2) To ingore the gravity .  we often set sping property to very large. I try about 50000.
     I disable gravity but it doesn't help . I think the spring property also take effect. But disable spring    property makes the system unstable.From Physx's document,spring is the amount of force to apply to move the joint to its target position proportional to the distance from the target. I don't know why disble it cause unstable.
    (3)  What do I want to do?  I want to write my thesis . I want to apply MRDS for industrial robot . for kinematics simulation and dynamics simulation.  I want to let MRDS do the work of kinematics simulation and collision simulation.  the first step is that the Matlab robot toolbox will do the dynamics simulation , the feedback of joint angles will export to MRDS for render and path planning. 

         If  the reason is as what I say, any way to build a pure kinematics articulated model in MRDS?


    Tuesday, February 17, 2009 1:37 AM
  • You might be able to get this to work but we don't support physics engines other than PhysX. I.e., making external physics engines work with RDS might be difficult and we have not tried doing anything like this ourselves.
    Tuesday, February 17, 2009 6:52 PM
  • Hi :
        So I can't disable PHYSX Engine? BTW, can I set the sping property to zero? I try this but get an unstable system.
    Tuesday, March 03, 2009 5:13 AM