M02AS Position hold tolerance

I have an application where I am moving an anvil to a position and back. I am using a high speed servo valve to control the hydraulic fluid.

My problem is once I am in the holding position the servo valve is constantly working against a pressure that is making the anvil drift. I want to reduce the work the valve is doing; the drift rate is very slow ~6mm in 30s; the operational frequency of this valve is approx 1 operation in 10s total movement of 17mm per stroke; thus the drift is of little concern.

If I could keep the output of the M02AS card at 0V unless outside say 2mm from set point this would be ideal.

I thought this is what the "position lock tolerance" setting was for. Reading the help file says that this is not what I am looking for. Changing this value also has no effect on what the voltage output is between operations.

The reason we are using servo valves is for the speed of the operation; each operation lasts for approx 0.620s for a down-stop-up movement; we may want to push this harder in the future.

For background I am using the MAM command to make the moves; feedback is from tempersonic sensors with a resolution of 0.01mm. The control action itself is very nice and smooth.

If I understand you correctly, you don't need holding position power (you said 0V when at rest and within the deadband). In that case, once your move completes, turn off the servo with a MSF. That will remove power. Monitor the actual position vs desired position and if it is more than 2mm, then turn the servo back on (MSO) and move back to position (MAM).

Thanks for the reply. I had already thought of this and it tried that before posting.

This introduces too much extra delay into the system approx extra 0.6s. This application is also a trial for a much higher frequency operation using the same high speed valves. Operational cycle will be approx 2 - 6 times in a 5s period with an operating period of (targeted) 0.3s; current operation is approx 0.6s.

In this new application drift is even less of a concern due to the high operating cycle frequency.

In the current application there are approx 4000 operations in a 24hr period; adding 0.6s to each operation is not really an option.

In the new application there are upwards of 28000 operations in a 24hr period. Adding even 0.05s to each operation is not an option.