Looking for input from python/odrive experts on whether there is a possibility of mixing the statistics being logged by a pi connected to two odrives (each controlling one axis of a 2-axis project - call the two axes “ROLL” and “TILT”):
Physically, these are two separate odrive (pro) controllers, connected to an industrial-grade USB hub, then through a USB signal isolator, then to a single USB port on the pi. Motors and encoders are identical on the two axes, but their ranges of motion and behaviors are different.
We had an incident where we cooked a motor and melted the surrounding plastic parts on the TILT axis. But the most obvious record of that (railed at max torque for 25 seconds) shows up in the logs as the ROLL axis. It can’t, however, be a full swap of the two axes datasets (or control) from the very beginning, as most of the time the data, control, physical behavior, etc. align with the intended assignments.
Initialization and initial assignment of the two axes is by serial number:
roll_addr = "347436783330" # odrive SN
tilt_addr = "345136613330" # odrive SN
...
def setup_odrive_pros():
global roll_drive, roll_axis, tilt_drive, tilt_axis
# establish communication with odrives. Set them idle, then check for errors.
err = 0
roll_drive = odrive.find_any(serial_number=roll_addr)
roll_axis = roll_drive.axis0
roll_axis.requested_state = AxisState.IDLE # set axes IDLE
tilt_drive = odrive.find_any(serial_number=tilt_addr)
tilt_axis = tilt_drive.axis0
tilt_axis.requested_state = AxisState.IDLE # set axes IDLE
# disable all axes' watchdog timers for now
roll_axis.config.enable_watchdog = False
tilt_axis.config.enable_watchdog = False
...
Logging (and control) is by the objects initialized above:
def log_stats_check_errs(status, step_idx, header=False):
global roll_drive, tilt_drive, roll_axis, tilt_axis, cycle_count, cycle_start_t, errs
if header: # only stuff this one in when asked (likely first call)
logging.info('DATA1, c, elapsed(s), status, (idx), errs, '
'(R), r_pos, r_dest, r_vel, r_vset, r_mpwr, r_teff, r_ibus, r_vbus, '
'(T), t_pos, t_dest, t_vel, t_vset, t_mpwr, t_teff, t_ibus, t_vbus,')
# fetch data values
data_t = time.time()
r_pos = roll_axis.pos_vel_mapper.pos_rel
r_dest = roll_axis.controller.input_pos
r_vel = roll_axis.pos_vel_mapper.vel
r_vset = roll_axis.controller.vel_setpoint
r_teff = roll_axis.controller.effective_torque_setpoint
r_ibus = roll_drive.ibus
r_vbus = roll_drive.vbus_voltage
t_pos = tilt_axis.pos_vel_mapper.pos_rel
t_dest = tilt_axis.controller.input_pos
t_vel = tilt_axis.pos_vel_mapper.vel
t_vset = tilt_axis.controller.vel_setpoint
t_teff = tilt_axis.controller.effective_torque_setpoint
t_ibus = tilt_drive.ibus
t_vbus = tilt_drive.vbus_voltage
if RT_FW_v_064_OR_OLDER:
r_mpwr = roll_axis.controller.mechanical_power
t_mpwr = tilt_axis.controller.mechanical_power
else: # compatability with odrive fw 0.6.5 ++
r_mpwr = roll_axis.motor.mechanical_power
t_mpwr = tilt_axis.motor.mechanical_power
# check for errors
_rep = check_for_odrive_errs_pro() # check for drive errors
if len(_rep) > 0: # if any errors found...
logging.info('Drive Errors found! ' + ', '.join(_rep)) # log them
errs += 2
status = 'drive_error'
# compile the useful bits into a return object
latest = Status_var() # create status var
latest.status = status
latest.data_t = data_t
latest.elapsed = data_t - cycle_start_t
latest.r_dest = r_dest
latest.r_pos = r_pos
latest.r_vel = r_vel
latest.t_dest = t_dest
latest.t_pos = t_pos
latest.t_vel = t_vel
# now log the data, with (new) status
logging.info('DATA1, {}, {:.3f}, {}, {}, {:.1f}, '
'(R), {:.3f}, {:.3f}, {:.3f}, {:.3f}, {:.3f}, {:.4f}, {:.2f}, {:.2f}, '
'(T), {:.3f}, {:.3f}, {:.3f}, {:.3f}, {:.3f}, {:.4f}, {:.2f}, {:.2f},'
.format(cycle_count, latest.elapsed, status, step_idx, errs,
r_pos, r_dest, r_vel, r_vset, r_mpwr, r_teff, r_ibus, r_vbus,
t_pos, t_dest, t_vel, t_vset, t_mpwr, t_teff, t_ibus, t_vbus))
return latest
...
Is there something about the subtleties of python and/or the USB connection that I’m missing, whereby the reads from roll_drive and roll_axis could actually be fetching data from the tilt odrive, and only some of the time (in blocks)??
Thanks for your brain time