I've created a robot in the engine by piecing it together in the engine and connecting the parts via HingeJointDescriptors.

I want to get a smooth joint trajectory using the LSPB method. I have to apply a torque to the axis of rotation to actually get the joint to move. I multiply by an arbitrary offset value to increase the velocity enough to move the joint. To get it to stop I find the current angular velocity then apply a torque equal to the joint mass * the negative of the angular velocity vector. This somewhat works, but there is a degree of error involved.

is there an easier way to move and stop the joint? Ideally, I want to say "move to this angle" [angle here].

Hello,

A classic way to perform this task in robotics is a PID controller
http://en.wikipedia.org/wiki/PID_controller
Basically, the power commands sent to a motor is proportional to the angle error.

In the beta, we have provided a "DriveJoint" that simulates a motor (a HingeJoint with a TargetVelocity field).
Unfortunately, you can't read the current "angle" value on this joint.

In the release, we have removed the DriveJoint and added a MotorizedHingeJoint and a MotorizedSliderJoint where you can both set a target velocity and read the current joint position.

You can still use PID controllers with the beta but you have to write some code to calculate the angle between the two actors moved by the joint (by using their world matrix).

Regards,
Vincent