I just received my picar-x. I installed the motors, and plugged in the cable, installed the software. While during calibration following the tutorial, the motors do not move at all. There are sound from the board, but the motors are not working (please see the video here). Does anyone know what could be the potential issue?
It’s because the motor power set during calibration was too low, causing the motor to fail to start. It has been changed, try to update it like this:
cd ~/picar-x
git pull origin v2.0
Then try running the calibration again.
I think I know what is broken. The little stuff between motors plugs (marked in red box) is burned after I use the v2.0. It might be the reason to cause the motors not working.
The beeping sound when running calibration is the sound the motor makes because the PWM value does not reach the motor start threshold. Burned is the motor driver chip. It is possible that the motor has not been rotating for a long time and continues to give the motor output, the motor is equivalent to blocking the rotation, and the current is too high for a long time, resulting in the motor driver chip overheating and burning.
Please contact this after-sales service email service@sunfounder.com, the after-sales service team will arrange to send you a new Robot Hat. After you receive the new Robot Hat, please confirm whether you have updated the latest software. Before that, it may be due to the cache file generated by the local folder after installation, which causes the git pulling failure.
You can try clearing the local cache and try pulling again. Note that the following will clear all the changes you have made in the picar-x folder:
cd ~/picar-x
git reset HEAD --hard
git pull origin v2.0
Then run the command to confirm that the speed of the motor test was updated successfully:
cat ~/picar-x/example/calibration/calibration.py | grep "px_power = "
This command outputs px_power = 30, which means the update was successful.
If the root cause is due to the fact that the motors have not been rotating for a long time, does it mean that the motors need to be replaced as well? What if the received new robot hat is burned by the same motors?
First let’s check what the speed of your current motor drive is, again run this command to see what the speed of the motor is set to when you calibrate
cat ~/picar-x/example/calibration/calibration.py | grep "px_power = "
If the return result is px_power = 30, it means it is already up to date.
Secondly, to tell you about the burning principle of this chip: calibration set the motor drive PWM value is too low, this value does not reach the motor start value, resulting in the motor wanting to turn, but the force is not enough. And because the DC motor is a set of wound coils inside, the motor does not turn up if the equivalent of a short circuit. This leads to the problem of too much current. But because the PWM is set low, this short circuit is not as serious. So only in a long time let in the motor does not turn up and continue to give motor output, the chip heat accumulation, and eventually will lead to motor driver chip burned.
So, in order to avoid burning the motor driver chip again after you receive Robot Hat, you can run calibrate, the motor again when this situation, timely stop the motor, close the program can be. If this still happens, please contact us in time.
There is another way to determine if the motor is not strong enough to rotate, install the wheel to the motor, and when the motor beeps after running calibrate, try to manually turn the wheel in two directions (clockwise and counterclockwise) to try to give the motor an initial speed to see if the motor can turn up.
Finally, if you suspect that the motor is jammed, resulting in blocked rotation, you can also put the wheel on, unplug the motor wiring, and then manually turn the wheel and then release it, you can see that the wheel should continue to rotate some under the action of inertia, you can feel whether the motor is jammed. If you feel unable to judge, you can send a video up, we help you see.
I did double check the px_power. It is set up 30 in v2.0.
I also unplugged the motors, and manually turned the wheel and release it. Here is the video. I can feel a little bit inertia for one of the wheel.
BTW, I have already sent an email to service@sunfounder.com. It would be nice if you could help to speed up their processing.
The motor seems to be normal, when you receive the Robot Hat pay attention to the situation, if it does not turn again, stop the motor in time will not burn out. Generally within 5 seconds is no problem.