Force feedback?

[GORDYKD]

Is anyone using haptic or force feedback during teach mode? If so please describe your hardware and setup.

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[TomKerekes]

Hi GORDYKD,

I'm not exactly sure what you are asking but the TeachMotion C# example include with KMotion has code to utilize a force feedback joystick. Besides the simple on screen joystick (used in the video below), or a standard Gamepad, if a force feedback capable device is connected the program should detect it and utilize it. With the idea being that the operator could then feel how close an axis is to a restriction, or potentially the force being applied by the machine. Microsoft's DirectInput API is used. See the file ForceFeedbackJoystick.cs

The TeachMotion Example





One such Joystick - Microsoft SideWinder Force Feedback 2

[GORDYKD]

Thank you for the reply. Sorry for the long delay in response. I am mainly interested in being able to feel the force applied by the machine servos. Is that possible?

[TomKerekes]

Hi GORDYKD,

Could you describe what you mean in more detail?

If using our SnapAmp the motor current (torque/force) would be available to KFLOP. If using 3rd party Analog Drives in torque mode the commanded output would be torque/force. Otherwise you would need to somehow measure current/torque/force and interface it back to KFLOP.

Then this value would need to be upladed to the PC and interfaced to the haptic device.

[GORDYKD]

Good morning Tom,
This is a metal spinning operation and the operator is having great difficulty teaching the control because he can't feel the force as he is used to with a manual machine. There is a lot of "art" to the process. I am just hoping that a feedback joystick might give him the necessary tactile feedback to be able to make it work. Yes the system is using the SnapAmp. Will it need any modification to setup or code to use the sidewinder or will it pick it up automatically?

Thanks

[TomKerekes]

Hi GORDYKD,

The TeachMotion example should auto detect the presence of a force feedback joystick using Microsoft.DirectX.DirectInput. See the file: \PC VCS Examples\TeachMotion\ForceFeedbackJoystick.cs. But this was written many years ago and you may need to update/debug it if it doesn't.

The code applies a force in the Y direction depending on how close the tool is to the measured spinning die profile. See the code before the call to FFJoy.ApplyForce(ForceX, ForceY); in Form1.cs.

You would need to modify the code to instead read the motor current/torque and use that. This would involve a C Program in KFLOP to place the 3 phase measured current into a persist variable for access by the PC. Then the PC's C# code would need to be changed to read the persist variable and apply it as a force to the joystick.

Note this forms a feedback loop with a human and many things and some delays in the loop so can easily go unstable. For example, the operator pushes the joystick (with little resistance) too much, then the servo hits something, force increases too much, then the joystick jerks back, servo reverses, force drops to zero, etc. and repeating forming an oscillation. So it is somewhat complicated to tune. The TeachMotion Code combines the distance to the die, the velocity of the servo towards the die, and a low pass filter to achieve a decent "feel".

HTH