mBot motor speed = 50

#1

Is there an issue with the mBot motors running when issued the standard mBlock Robots command “set motor Mx speed + or -50”? The motors appear to work fine with default speeds +/-100 or +/-255, but will not start when set to +/-50. All that is heard is an audible tone, but no motor movement. (I have tried this with an external power source at +5.5v to eliminate possible battery problems).

#2

I have the same issue. SPEED = 100 works fine, but not 50. Expecially, run forward and run backward do not work.

#3

@dave, I had an exchange with @Pioneer on this on another thread … here. (I initially didn’t get a response to the post on this thread, and was following up on what I thought might be a related motor topic).

He basically confirmed that it takes a motor speed setting of 100 (or higher depending on surface) to get the motors going. (I was able to get them spinning at 75 in free air, but haven’t played around with it too much more). Not exactly sure why there are +/-50 settings in the dropdown menu for motor speed as they apparently won’t start at this low of a level … perhaps this will be changed in future mBlock revisions.

(I haven’t tried seeing if once started at a higher speed the motors can be switched to the slower +/-50 levels).

#4

Updating my last post … @Pioneer did not actually ‘confirm’ the motor speed needed to be higher than 50 to operate … I just inferred from his comments that 100 was likely a more appropriate value for operation in best case conditions (i.e. a hard surface). Sorry if I misspoke. (… and sorry I initially posted this on the other thread by mistake).

#5

@davepark0323, normally, turn around need more torque than moving forward and backward, thats why you need to increase the speed value. And the speed value depends on the friction of the surface, you can try higher value, if still cant work, you can send email to us: support@makeblock.cc

#6

@larry, we are appreciated of your explaination, which can help to eliminate the misunderstanding of other customers.

#7

I don’t agree @Pioneer about the motor speed needs be more than 50. I created a very simple example to stop mBot when a linefollower returns 0 with a motor speed 100. In this case, my mBot always fell down from my table. And I tried to use the motor speed 50, sometimes, it worked fine and my mBot stopped before falling down, but sometimes, it turned left or right, not moved forward. Even examples in website is using the motor speed 50.

#8

@davepark0323, mBot has some direction deviation, after running some distance, mBot would turn left or right, its normal, and cant be completely eliminated.

#9

Related to this, I notice two additional things…

  1. From a dead stop if you set the left and right motors to 50 (or 100), you’ll get a buck sometimes and the mbot will kick left or right before starting forward.

As expected, same result if you just use move forward.

  1. Sometimes I do find that the mbot won’t start forward at 50. What I do is set the motors to 100 and then ramp down to 50. This seems to work but there is still the occasional kicking left/right.
#10