mBot motors not in sync

#1

I purchased the mbot for my son for Christmas.

I am not able to get my mBot motors in sync to make it driving straight forward.
I would think there is an issue with 1 of the motors, because the speed values I need to provide are far apart from each other.

For example some speed values to make it drive less or more straight forward.
M1: 190 and M2: 140
M1: 255 and M2: 160

The motors are clean, so no dust and they also don’t touch the frame of the robot.

Any idea what the problem could be?

Thanks.

mBot DC motors not in sync
#2

Try to loosen the screw in the middle of the slower wheel a bit

#3

Thanks for the feedback. I have tried your suggestion, but no difference.
Any other suggestions?
Should I buy a new motor, or is this covered by guarantee?

Thanks

#4

Hi KimMonnens,

Please kindly take a video for the bahaves on mBot and send it to tec-support@makeblock.com

#5

The motors used by mBot are inexpensive DC motors which are not calibrated. It is natural to see speed differences between the motors even though you are using the same “speed” value. In particular, if you use the “go ‘forward’ at speed ‘100’” block and the motors are not calibrated the same, the mBot will not move straight. You’ll have to use two blocks: “set motor ‘M1’ speed ‘190’” and “set motor ‘M2’ speed ‘140’” to get your mBot to drive straight.

Your options are to buy one or more DC motors from Amazon/eBay/AliExpress/etc. and hope they are in better sync or maybe MakeBlock will send you new DC motors. I do have to say, that of the 45 mBots that we use at TechTown, only one or two do not drive straight.

/Aram

#6

Hello~~ May i know the motor speed is in term of pwm or rpm.for example motor left and motor right i set to speed 100. This value is in pwm or rpm?
Thanks for replies much appreciate.

mBot motor speed in pwm or rpm?
#7

Hi HAO,

The motor speed is in term of rpm.
But in mBlock program, set to speed 100 doesn’t mean that the motor speed is 100 rpm, the 100 is actual a proportion, its actual speed is determined by the load and power provided by the Mainboard.

Take this condition as example: the mainboard can provide full power to the motor and there is no load on a motor which has 185 ±10%rpm no-load speed, when you set to speed 100, the actual speed of this motor is 100/255*185 (rpm).

#8