I have a small question regarding the speed limit of a stepper motor.
I understand that the MMS “speed limit” parameter applies to the speed as it is being measured by the position sensor.
When the (stepper) motor tries to reach a target setpoint, the speed increases but there seem to be speed limit. If the mechanism is at a limit, or the sensor is not correctly driven, it could lead the motor to dangerous speeds.
I would like to limit the speed in terms of rev/s or steps/s, in other words the phases frequency applied to the the stepper motor.
Hi Marc
The CVL parameter in Granity/Goals tab will limit the maximum speed.
Kind regards, Esa
Sorry, this does not work.
[BTW : out machine is a “position control” mode]
CVL seems to “filter” the position setpoint (replace jumps by ramps) so it limits the rotation speed in closed-loop, under the position sensor control.
Whenever the mechanics goes open-loop (for any reason, for example the mechanism is at its limit, or blocked), the motor speed increases. I can hear it very clearly going to several kHz (whereas a sensible step frequency should be no more than 100 Hz).
Hi Marc
Please describe your system in very detailed manner, and please also reply with your IONI configuration file.
Kind regards, Esa
The system is a position control servo, with a small stepper motor driving a worm screw, and no limit switches. Under some circumstances, unwanted events may occur (that’s life), for example the targeted setpoint cannot be reached or the mechanics gets stuck. In those cases, the motor will rotate to adjust the position, so it rotates and rotates and accelerates more and more. I can make it accelerate slowly but it accelerates anyway, I measured up to 6 kHz on the phases.
29_avril.drc (9.5 KB)
Hi
Is your encoder connected to the motor or the worm gear?
Your configuration shows you are using closed loop mode 2, but your PIV parameters don’t follow our wiki suggestions.
https://granitedevices.com/wiki/Using_stepping_motor_with_IONI
What is the intended mode for the motor? Open loop, stepper with encoder for position error, or servo mode?
Kind regards, Esa
Mode 2, I suppose.
I have been trying mode 3 already but MT=2 phases AC does not rotate the actuator.
I’ll try this again after my holidays - each in turn 
Hi
Please read:
https://granitedevices.com/wiki/Essential_Basics
https://granitedevices.com/wiki/Servo_motor_torque_mode_test
Kind regards, Esa
I tried with [MT] = “2 phases AC” motor.
The motor replicates the sensor motion, with a fixed ratio (independent of [AXS], [MUL] and [DIV]). There is no motion dynamics, as there is no speed per se even with a high [KVP] value. Setpoints changes have no effect.