Stumped by Servos

I was hoping that someone could give me some guidance with the Minie New6Dof servo motor. I’ve looked at the examples given for regular motors, but unfortunately I still can’t get the servo to work. It is reported as being enabled, but no movement occurs and the joints are still completely loose.

Here’s some example code:

for (PhysicsJoint j : physics.getPhysicsSpace().getJointList()) {
        if (j instanceof New6Dof){
            ((New6Dof) j).set(MotorParam.ServoTarget,4,(float)Math.toRadians(270));
            ((New6Dof) j).set(MotorParam.TargetVelocity,4,0.4f);
            ((New6Dof) j).set(MotorParam.MaxMotorForce,4,2000);
            ((New6Dof) j).getRotationMotor(1).setServoEnabled(true);

            //Outputs true
            System.out.println(((New6Dof) j).isServoEnabled(4));

I assume ServoTarget is an angle expressed in Radians. I’ve messed around with various values for Target velocity and MaxMotorForce (including omitting the lines entirely) as I have no idea what the correct units are. I’m not even sure that they are used in the context of the servo.

By way of background, I’ve modelled a hexapod robot from a collection of RigidBodyControls connected with New6Dofs. After a bit of work, I’ve finally got to the stage of having a working rag doll, with the correct ranges of movement etc and was feeling pretty chuffed! :grin:

Would really appreciate any advice, since I can’t find much information on this, other than what’s in the Minie documentation. It would be brilliant if I could get it working though, as it seems to do exactly what I need it to.

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There’s a servo example here:

I encourage you to experiment with it. Hack away!

Some quick answers:

  1. Yes, all physics-joint rotations are in radians.
  2. Max motor force is very important. Start high (like 9e9f).
  3. Target velocity is also important. For rotations, I believe the units are radians per second.
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Sorry, not sure how I managed to miss this, but it’s exactly what I needed - thanks! Will hack away and see how I get on. :smiley:

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Just in case anyone else has the same problem, it looks like setMotorEnabled(true) needs to be called in addition to setServoEnabled in order for the joint to work.

So now I have movement, now I just need to get the movement I want :slight_smile:

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