Closed Loop violent vibrations

Support
1

Hello all,

I was using Sensor-less mode because I was waiting for he encoders and the motors were working with some minor issues when stopping abruptly.
I have received the AMT102-V encoders and have been trying the past couple of days to use the ODrive tool to control the motors but to no avail. It is time I ask for some help!

So the current setup is:

  • Odrive 24v powered by a PSU at 12.5V 60A( can go higher but the motors are limited to 15v and don’t want to risk it!)

  • Turnigy Aerodrive SK3 - 2830-920kv (out runner)

  • and finally the AMT102-V encoder.

The encoder came without a wire so I made my own using the housings and pins required as mentioned in its datasheet and solder them direlty onto the Odrive.

What I have tried so far is :

  1. reset the odrive and calibrate it

    odrv1.erase_configuration()
    odrv1.reboot()
    odrv1.axis0.encoder.config.use_index = True
    odrv1.axis0.requested_state = AXIS_STATE_FULL_CALIBRATION_SEQUENCE
    odrv1.axis0.encoder.config.pre_calibrated = True
    odrv1.axis0.motor.config.pre_calibrated = True
    odrv1.axis0.config.startup_encoder_index_search = True
    odrv1.axis0.config.startup_closed_loop_control = True
    odrv1.save_configuration()
    odrv1.reboot()

  2. after calibration enter the closed loop state

  3. Try setting a pos_setpoint (eg 10000) or vel_setpoint — Nothing happens or I get the ERROR_OVERSPEED)

  4. Increase the vel_limit to 100000 - This solves the overspeed, however it starts vibrating and the motor isn’t moving at all.

The above steps were with the default values.

I have tried the exact same steps with the values ( gains ) I got from the Sensoreless setup and increase the motor.config.current_lim to 20. I know that the motors were working with these values.

Here is the output from the odrv.axis:

In [77]: odrv1.axis0
Out[77]: 
error = 0x0000 (int)
step_dir_active = False (bool)
current_state = 1 (int)
requested_state = 0 (int)
loop_counter = 32738166 (int)
lockin_state = 0 (int)
config:
  startup_motor_calibration = False (bool)
  startup_encoder_index_search = True (bool)
  startup_encoder_offset_calibration = False (bool)
  startup_closed_loop_control = True (bool)
  startup_sensorless_control = False (bool)
  enable_step_dir = False (bool)
  counts_per_step = 2.0 (float)
  watchdog_timeout = 0.0 (float)
  step_gpio_pin = 1 (int)
  dir_gpio_pin = 2 (int)
  calibration_lockin: ...
  sensorless_ramp: ...
  general_lockin: ...
motor:
  error = 0x0000 (int)
  armed_state = 0 (int)
  is_calibrated = True (bool)
  current_meas_phB = -0.28109169006347656 (float)
  current_meas_phC = 0.035080693662166595 (float)
  DC_calib_phB = -1.652514934539795 (float)
  DC_calib_phC = 0.08589068055152893 (float)
  phase_current_rev_gain = 0.02500000037252903 (float)
  thermal_current_lim = 48.00704574584961 (float)
  get_inverter_temp()
  current_control: ...
  gate_driver: ...
  timing_log: ...
  config: ...
controller:
  error = 0x0000 (int)
  pos_setpoint = -7610.765625 (float)
  vel_setpoint = 0.0 (float)
  vel_integrator_current = -0.3915861248970032 (float)
  current_setpoint = 0.0 (float)
  vel_ramp_target = 0.0 (float)
  vel_ramp_enable = False (bool)
  config: ...
  set_pos_setpoint(pos_setpoint: float, vel_feed_forward: float, current_feed_forward: float)
  set_vel_setpoint(vel_setpoint: float, current_feed_forward: float)
  set_current_setpoint(current_setpoint: float)
  move_to_pos(pos_setpoint: float)
  move_incremental(displacement: float, from_goal_point: bool)
  start_anticogging_calibration()
encoder:
  error = 0x0000 (int)
  is_ready = True (bool)
  index_found = True (bool)
  shadow_count = -5636 (int)
  count_in_cpr = 2556 (int)
  interpolation = 0.5 (float)
  phase = 0.9716787338256836 (float)
  pos_estimate = -5635.765625 (float)
  pos_cpr = 2556.234375 (float)
  hall_state = 0 (int)
  vel_estimate = 0.0 (float)
  calib_scan_response = 9329.0 (float)
  config: ...
  set_linear_count(count: int)
sensorless_estimator:
  error = 0x0000 (int)
  phase = -2.2962546348571777 (float)
  pll_pos = -2.297368049621582 (float)
  vel_estimate = 0.04372486472129822 (float)
  config: ...
trap_traj:
  config: ...
watchdog_feed()

HW / FW versions:

hw_version_major = 3 (int)
hw_version_minor = 6 (int)
hw_version_variant = 24 (int)
fw_version_major = 0 (int)
fw_version_minor = 4 (int)
fw_version_revision = 11 (int)
fw_version_unreleased = 0 (int)

Also, I have another question about the tuning procedure. Do you enter the closed loop mode and set a vel or pos_setpoint so it will be ‘energized’ and then you start the tuning? If not could someone please clarify the steps before initializing the tuning procedure?

Thank you in advance,

Michail

2

What control mode are you in when you’re trying to send velocity commands?

3

@Wetmelon When I try controlling it with the vel_setpoint coommand the control_mode is set to velocity control and when I try to control it with the position setpoint I switch to the position control.

I made some progress, the default values were not working with this motor ( its KV are much higher than most of the threads ive seen here ). I have reduced the gains quite significantly. To be exact :

odrv0.axis0.controller.config.pos_gain = 5 
odrv0.axis0.controller.config.vel_gain = 0.00005
odrv0.axis0.controller.config.vel_integrator_gain = 0.00025

also changed these :

odrv0.axis0.motor.config.current_lim = 15
odrv0.axis0.motor.config.current_lim_tolerance = 1.5
odrv0.axis0.controller.config.vel_limit = 100000

However, like that if i try to stop the motor with my finger its quite easy. Max A the motor can take is 17A.
Do you think it needs further tuning ? if so any empirical input would be very helpful!

Thank you very much.

4

When you put your finger on it and stop the motor, check motor.current_control.Iq_setpoint. If that’s 15, then you’re putting all of your current to the motor already.

5

@Wetmelon Thank you very much! Will check that first thing thing the morning on Monday!