[NXC] RotateMotor with speed regulation - How?

[ricardocrl]

Hi everyone,

When using RotateMotor, the speed is not regulated. Does anyone have an idea on how to make this happen?

I found a way that works:

Code: Select all

OnFwdRegEx(motor, speed, OUT_REGMODE_SPEED, RESET_NONE);
Wait(1);
SetOutput(motor, TachoLimitField, angle, UpdateFlagsField, UF_UPDATE_TACHO_LIMIT);

The only problem with this method is that after reaching the position, the motor will Coast and will not control its position, around the target, like it happens with RotateMotor().
Any suggestion?

[afanofosc]

As currently implemented, all the RotateMotor API functions use REGMODE_SYNC even when you only control a single motor. I could change that so when you only use a single motor that it uses speed regulation instead of synchronization.

John Hansen

[ricardocrl]

As currently implemented, all the RotateMotor API functions use REGMODE_SYNC even when you only control a single motor. I could change that so when you only use a single motor that it uses speed regulation instead of synchronization.

John Hansen

Hi John, sorry for the delay.

That is probably a very nice enhancement, I would say.

But I have a question... What is contributing to the fact that the motor will go around the position, stabilizing for a moment, before it returns from the RotateMotor job?
Do you understand my question? I mean, when I ask with a simple SetOutput commands, setting a OUT_REGMODE_SPEED or OUT_REGMODE_SYNC, plus a tacho limit, the motor will run till that position and will stop working on it after it reaches it for the first time, coasting, letting the motor continuing turning.

What is RotateMotor triggering in the Firmware (other than the mode and the tacholimit)?

[afanofosc]

The code in RotateMotor looks like this:

Code: Select all

subroutine __RotateMotor0
  brtst EQ, __rotate_Done0, __rotate_angle0
  sign __rotate_thePower0, __rotate_angle0
  abs __rotate_theAngle0, __rotate_angle0
  mul __rotate_thePower0, __rotate_thePower0, __rotate_power0 // convert __rotate_power to negative value if __rotate_angle is negative.

  set __rotate_theUF0, UF_UPDATE_TACHO_LIMIT+UF_UPDATE_SPEED+UF_UPDATE_MODE+UF_UPDATE_PID_VALUES
  brtst EQ, __rotate_NoSync0, __rotate_sync0
  set __rotate_theOM0, OUT_MODE_MOTORON+OUT_MODE_BRAKE+OUT_MODE_REGULATED
  set __rotate_theRM0, OUT_REGMODE_SYNC
  mov __rotate_theTurnPct0, __rotate_turnpct0
  brtst EQ, __rotate_Start0, __rotate_theTurnPct0
  add __rotate_theUF0, __rotate_theUF0, UF_UPDATE_RESET_BLOCK_COUNT
  jmp __rotate_Start0
__rotate_NoSync0:
  set __rotate_theOM0, OUT_MODE_MOTORON+OUT_MODE_BRAKE
  set __rotate_theRM0, OUT_REGMODE_IDLE
  set __rotate_theTurnPct0, 0
__rotate_Start0:
  set __rotate_theRS0, OUT_RUNSTATE_RUNNING
  setout __rotate_ports0, OutputModeField, __rotate_theOM0, RegModeField, __rotate_theRM0, TachoLimitField, __rotate_theAngle0, RunStateField, __rotate_theRS0, RegPValueField, __rotate_theRVP0, RegIValueField, __rotate_theRVI0, RegDValueField, __rotate_theRVD0, PowerField, __rotate_thePower0, TurnRatioField, __rotate_turnpct0, UpdateFlagsField, __rotate_theUF0

  wait 0 // let the motor(s) start turning

  // Waits till the angle is reached
  index __rotate_firstPort0, __rotate_ports0, NA
__rotate_Running0:
  getout __rotate_power0, __rotate_firstPort0, PowerField
  brtst EQ, __rotate_doneRunning0, __rotate_power0
  getout __rotate_rs0, __rotate_firstPort0, RunStateField
  brcmp EQ, __rotate_Running0, __rotate_rs0, OUT_RUNSTATE_RUNNING
__rotate_doneRunning0:
  brtst EQ, __rotate_Reset0, __rotate_stop0 // skip the speed regulation phase if __rotate_stop is false

  // Regulates for speed = 0
  set __rotate_theOM0, OUT_MODE_MOTORON+OUT_MODE_BRAKE+OUT_MODE_REGULATED
  set __rotate_theUF0, UF_UPDATE_TACHO_LIMIT+UF_UPDATE_SPEED+UF_UPDATE_MODE
  setout __rotate_ports0, OutputModeField, __rotate_theOM0, RegModeField, OUT_REGMODE_SPEED, RunStateField, __rotate_theRS0, PowerField, 0, TurnRatioField, 0, TachoLimitField, 0, UpdateFlagsField, __rotate_theUF0

  wait 0 // let the firmware stop the motor(s)

  // Verifies that motor doesn't rotate for 50ms, else loops
  getout __rotate_RotCount0, __rotate_firstPort0, TachoCountField
__rotate_Stabilize0:
  mov __rotate_OldRotCount0, __rotate_RotCount0
  wait 50
  // check rotation
  getout __rotate_RotCount0, __rotate_firstPort0, TachoCountField
  brcmp NEQ, __rotate_Stabilize0, __rotate_OldRotCount0, __rotate_RotCount0

  // now remove the brake
  set __rotate_theOM0, OUT_MODE_COAST+OUT_MODE_REGULATED
  setout __rotate_ports0, RegModeField, __rotate_theRM0, RunStateField, OUT_RUNSTATE_IDLE, OutputModeField, __rotate_theOM0, UpdateFlagsField, UF_UPDATE_MODE
  wait 0 // let the firmware release the motor(s)

__rotate_Reset0:
  // maybe reset the block rotation count
  brtst EQ, __rotate_Done0, __rotate_theTurnPct0
  setout __rotate_ports0, UpdateFlagsField, UF_UPDATE_RESET_BLOCK_COUNT
__rotate_Done0:
  return
ends

This is pretty easy to translate into NXC, if you need to. I will likely change these low level routines to use speed regulation if the rotate_sync variable is true and you are only controlling a single motor.

John Hansen