New ur modern driver ros-control follow joint trajectory

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This uses the pos_based_pos_traj_controller, can I use the vel_based_pos_traj_controller? but use the same action client?

The link I posted was just an example. A few lines down the velocity-based joint_trajectory_controller is configured (here).

They expose the exact same FollowJointTrajectory action server.

Thanks very much, I realised that that part of the yaml is there. My actual question should be: Do we need a different trajectory that specifies the velocity instead of the position of every way point? Or does the driver already work out the velocity from the position specified? Anyway, I tried using the vel_based action server but then the ur3 stopped by the controller because of safety! I am not sure why yet.

The actual error was: A dialogue box with the title Protective Stop, the box contains: C153A1: Protective Stop: Postion deviates from path: Shoulder.

I have tried all afternoon. It seems that the behaviour of the ur3 depends on the velocity that it moves. There is a slider on the UR teach pandent and can be used to adjust the speed the manipulator moves. When it is 100%, when the manipulator halfway to the destination, it was stopped because its position deviates from the path. When the slider is used to reduce the speed of the manipulator to 70%, it crashes on the workpiece before it reaches the target (or goal). When the speed is 80%, it still crashes on the workpiece but nearer to the target. So, it seems the position of the end effector depends on the speed of movement as well as the weight of the end effector. Is this true? I am just guessing.

You cannot use the slider on the TP: it must be at 100% always. Otherwise the assumptions in the driver about performance of the robot and the influence of the parameters for the motion commands don't hold and nothing will work correctly.

But you still haven't answered my questions: are you using a regular UR3 or an e-series, and are you using the kinetic-devel branch of ur_modern_driver?

I'm sorry. Yes, I am using a regular UR3 not an e-series. I am using the kinetic-devel branch of the ur_modern_driver.

Further my questions, does it mean that the payload must be accurately specified? It seams that all these relationship of position, velocity and acceleration depends also on the inertia. So the pay load is very important and sensitive. Isn't it?