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Hi, I'm trying to build a balancing robot like B-Robot. A bought the same Driver and Motor. (This is the motor data sheet: https://s3-ap-southeast-1.amazonaws.com/...20RevA.pdf).

This is the minimal robot : https://dl.dropboxusercontent.com/u/5096...G_0956.jpg

The wheels are 6 cm of radius and we use a poll A4988 driver.
The connection from the motors to the drivers are these:
2B : Blu
2A : Red
1A : Black
1B : Green

The VMOT is 19V

The problem is :
The motor doesn't have enough torque to move the wheel quickly. But Your robot had fast acceleration
The motor is locked
1. Smaller wheels - slower speed.
2. 19V can burn your drivers .
Your motors are rated at 1,68A 2.8V
(06-21-2015 01:50 PM)sasa999 Wrote: [ -> ]2. 19V can burn your drivers .
Your motors are rated at 1,68A 2.8V

This is not correct. The A4988 limits the current to what you set on the driver (in most configurations this is done with a pot) The voltage running through the stepper does not matter that much. What is important is that you dont exceed the rated amperage.

You can safely use the A4988 with up to 35v (this may vary depending on the carrier board that you are using) without destroying the board or the motor.
Max current is only part of this . Total power dissipation is important for not overheat. W = V x A
Hello Everyone,

Let me add m bit of advice to imbrendino and everyone else that might need.

First of all if you've made a custom build, the problem of the lack of strength may be related to the fact that you have not configured the stepper drives for microstepping.
Microstepping is mandatory for motors to be able to move anything attached to them (even if you only have the wheels attached).

So, as you already might have seen in the Arduino code, the B-Robot assumes 1/16 microstepping by default. This can be changed but what you should retain is that whatever you define in the code (variable microstepping), should be reflected in the A4988 microstepping configuration pins - MS1, MS2 and MS3.
You may refer to the A4988 in the Pololu website to learn more about installation and microstepping configuration.

On the tension/current limitation subject, you might want to follow an informative video (also from Pololu) to learn the procedure here.

By the way you should be fine with 19V on VMOT line, but you need to correctly configure both drivers (VRef) to prevent motor/driver damage.
For your motor the VRef should be around 0.6V on A4988.

Also very important: do not rewire anything in motor drivers when connected to power sources. ALWAYS disconnect power to rewire or change the stepping configuration.

HTH
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