Motors always trying to spin

[Maxolian1020]

Is it just be or when using pybricks my Motors always try to hold position or do something (even with stop.COAST) and you can hear that faint high pitch noise where the motor is trying to spin but it's literally not doing anything or sometimes it feels like and sounds like it's spinning on the inside but not the actual axle and it doesn't seem right for the motor. Prevents me from using pybricks, I'm sure it's not my motors maybe it's how I code idk... anyone else? (Happens with all motors different types and different hubs and multiple firmware installs)

[BertLindeman]

Hi Massimiliano,

Thank you for starting this discussion here.

You exclude as cause:

• the device type
• the firmware version

It is possible a number of motors have a problem, but let us not start with that.

Do you have a short pybricks program that shows your problem,
So I might be able to test it?

Of course best with motor type and firmware version.

The high pitch noise is usually heard if the motor is not completely stopped.
I hear it if resistance is stronger than the torque or duty_cycle of the motor can produce.

Bert

[BertLindeman]

(thanks David for the markup)

To better understand I removed devices not used, simplified and added a debug print of a snippet like this:

from pybricks.hubs import InventorHub

from pybricks.pupdevices import Motor
from pybricks.parameters import Port
from pybricks.tools import wait

hub = InventorHub(observe_channels=[1,2])
Gearbox = Motor(Port.B)
print("Checking Connection to Wheel and Pedal!")

print(hub.ble.observe(1))
print(hub.ble.observe(2))
GearboxPos = -90
Reverse = False

while True:

    if -95 <= GearboxPos <= -85:
        print(f'start gearbox run target   0 Gearbox.angle {Gearbox.angle()} gearboxpos:{GearboxPos}')
        Gearbox.run_target(1000, 0)
        Reverse = False
    elif -185 <= GearboxPos <= -175:
        print(f'start gearbox run target -20 Gearbox.angle {Gearbox.angle()} gearboxpos:{GearboxPos}')
        Gearbox.run_target(1000, -20)
        Reverse = True
    elif -5 <= GearboxPos <= 5:
        print(f'start gearbox run target -20 Gearbox.angle {Gearbox.angle()} gearboxpos:{GearboxPos}')
        Gearbox.run_target(1000, -20)
        Reverse = False
    elif 85 <= GearboxPos <= 95:
        print(f'start gearbox run target +20 Gearbox.angle {Gearbox.angle()} gearboxpos:{GearboxPos}')
        Gearbox.run_target(1000, 20)
        Reverse = False
    Gearbox.stop()
    wait(100)

Running the code I can not hear the high pitched sound from the motor, but I can feel very small movements.
That is due to the run_target.
There is often a small difference in the motor angle and the run_target tries to correct that 10 times a second (due to the wait(100) in the loop).

A snippet of the output I see:

start gearbox run target   0 Gearbox.angle 1 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 1 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 1 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 1 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 1 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 1 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 1 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 0 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 3 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 1 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 1 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 0 gearboxpos:-90
start gearbox run target   0 Gearbox.angle 0 gearboxpos:-90

So nothing problematic I think.

Bert

[Maxolian1020]

Thanks a lot for the help you're providing. I think it's pretty clear it's my code that is the problem, so now I need to fix that. But I was right with the small movements and since the motor maybe in your setup can spin easily mine has quite a bit of resistance and not enough power is generated during those Mirco adjustments. That's the only reason I can think it would cause the high pitched noise, how would I go about not allowing it to make those micro adjustments because even with the coast it still does it idk why, could you help more?

[BertLindeman]

Maybe only "do" the run_target if it is too much off the target for your program.
Now it is done each iteration of the loop and thus micromanaging it constantly..

[Maxolian1020]

Hey thanks for all the input, I just wanted to finish by saying that it's not a problem of pybricks but rather of my coding and yes I understood that running the run_target at each loop does cause a lot of micro adjustments causing what I was experiencing but it's actually normal for the code.

I have therefore re-written the whole code from bottom up, it's not finished yet, but here is a version MUCH improved and which doesn't have this micromanagement:

from pybricks.hubs import InventorHub
from pybricks.pupdevices import Motor, ColorSensor, UltrasonicSensor
from pybricks.parameters import Button, Color, Direction, Port, Side, Stop
from pybricks.robotics import DriveBase
from pybricks.tools import wait, StopWatch

hub = InventorHub(observe_channels=[1,2])
# Channel 1 == Steering Wheel
# Channel 2 == Pedal
# 1000 = Max Motor Speed

SteeringMotor = Motor(Port.D)
Gearbox = Motor(Port.B)
Drive = Motor(Port.F)
DifLock = Motor(Port.E)
DistSensor = UltrasonicSensor(Port.C)

RecievedPedal = hub.ble.observe(2)
RecievedSteering = hub.ble.observe(1)


#Variables Here

LastGear = "1"
PedalPressed = "0"
Reversed = False



print("Checking Connection to Wheel and Pedal!")

ConnectionDistancePedal = hub.ble.signal_strength(2)
ConnectionDistanceSteering = hub.ble.signal_strength(1)

#Functions Here

def CheckConnection():
    global ConnectionDistancePedal, ConnectionDistanceSteering
    for _ in range(50):
        TestConnection = [hub.ble.observe(1), hub.ble.observe(2)]
        ConnectionDistancePedal = hub.ble.signal_strength(2)
        ConnectionDistanceSteering = hub.ble.signal_strength(1)
        print("Connection Pedal:", ConnectionDistancePedal, "Connection Steering:", ConnectionDistanceSteering)
    if ConnectionDistancePedal > -128 and ConnectionDistanceSteering > -128:
        print("Connected Successfully to both Steering and Pedal!")
        return 1
    else:
        print("One of the two devices is not connected properly, PLEASE CHECK THE DEVICES BEFORE CONTINUING!")
        return 0

def switchGearbox():
    global LastGear, PedalPressed, Reversed
    SelectedGear = hub.ble.observe(1)
    SelectedGear = SelectedGear[1]
    PedalPressed = hub.ble.observe(2)
    PedalPressed = PedalPressed[1]

    if PedalPressed == 0 or PedalPressed == None:
            if abs(Gearbox.angle()) < 5:
                return
            else:
                print("NOT PRESSING PEDAL, MOVING TO NEUTRAL!")
                Gearbox.run_target(1000, 0, Stop.COAST)
                LastGear = "N-P"
            return
    else:
        if LastGear == SelectedGear:
            return
        else:
            if SelectedGear == "N":
                Gearbox.run_target(1000, 0, Stop.COAST)
                Reversed = False

            if SelectedGear == "R":
                Drive.stop()
                wait(100)
                Gearbox.run_target(1000, -35, Stop.COAST)
                Reversed = True
            
            if SelectedGear == "1":
                Gearbox.run_target(1000, -35, Stop.COAST)
                Reversed = False                
            
            if SelectedGear == "2":
                Gearbox.run_target(1000, 35, Stop.COAST)
                Reversed = False
            
            LastGear = SelectedGear

def RunEngine():
    EngineSpeed = hub.ble.observe(2)
    EngineSpeed = EngineSpeed[0]
    if EngineSpeed < 3:
        EngineSpeed = 0
        Drive.stop()
    else:
        if Reversed == True:
            EngineSpeed = (round(((EngineSpeed * 100) - 200)/3))*-1
            Drive.run(EngineSpeed)
        else:
            EngineSpeed = round(((EngineSpeed * 100) - 200)/3)
            Drive.run(EngineSpeed)

# Main Script Under Here

if CheckConnection() == 1:
    print("Continuing To Main Script")
else:
    print("Exiting the Script Error to connection!")
    hub.speaker.beep(200, 500)
    wait(500)
    hub.speaker.beep(250, 500)
    SystemExit()

while True:
    switchGearbox()
    RunEngine()

It is also much improved and simpler also because I upgraded the sending scripts on the other hubs so that they handle some of the work instead of having to do everything here, the sending hubs already send formatted data meaning that I only need to control the motors on this script instead of also parsing the data and formatting it meaning that it's all much simpler!

[BertLindeman]

Thank you for reporting back and sharing the updates you did.

Woud be great if you share a video after your project is finished.

Coding is fun!

Bert