Let's Make Robots!

4 channel motor cotroller with encoder mixing circuit


AttachmentSize
4_Channel_instruction_manual.pdf1.42 MB
Vendor's Description: 


This is the 4 channel motor controller from DAGU. Although designed for the Rover 5 chassis this controller is suitable for any small robot using Omni or Mecanum wheels.

Features:
4x low resistance FET "H" bridge rated for 4.5A stall current each.
4x Current sensing circuit with an output of aproximately 1V per amp of current draw.
4x Quadrature encoder mixing circuit.

The built in mixing circuitry mixes the 2 inputs from the quadrature encoder into a single output of twice the frequency. This allows a single interrupt pin to monitor both outputs of a quadrature encoder. Speed and distance can also be measured with twice the resolution compared to monitoring a single output. See the attached instruction manual for more details.

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

No it isnt antistatic foam it is neoprean and is just to rule out any issue of shorting while testing, it is not part of the final design. The frame is the Rover5 which is mostly plastic.

The connector you can see on the direction and PWM pins goes to a copper track board with header pins. This is so I can easily plug it into the Arduino. I have tested this connector with a multi meter several times to ensure there are no shorts and that each pin goes to the correction place. I have connected the Arduinos VIN pin to the VBatt connector on the motor controller so when i connect the battery pack the arduino will also be powered. I have then connected the Arduinos 5V pin to the VCC terminal on the motor controller. I have checked each connection to ensure it matches several examples I have seen on the web including your image above.

I am using the battery pack that was supplied with the Rover5 which is 6x 1.5v AA batteries.
Rover5image1

I was wondering what retailers carry this in the US.  I was searching around for some but all I found was Robotshop who says they "should" be getting some around Nov. 4th.  So even if they did get it then, I probally wouldn't get it till about the 10th.  I wanted to get one to use on my Rover 5 platform for the Google Science Fair and for a school project which is coming up.

Thanks

Joe 

Sorry,we sold out pretty quick and are producing a new batch now. Robot Savvy might have some but they are in the UK.

I just got one of these baby's and a red back spider controller to put on my Rover5 chassis. Is there some sample code for that kind of setup, do I need to customize the code from the Rover5_Arduino.zip?

I am assuming you have the 4 motor 4 encoder chassis and are using the original treads.

I do not have sample code for 4 motor and 4 encoder with treads. Only mecanum wheels which is a different ball park. Start by connecting your four motors up (ignore the encoders for now).

For the left motors connect you direction pins together so that both motors go in the same direction. Do the same for the right motors.

Try joining your left PWM pins together as well. Measure the current draw of both motors as you drive them forward and backwards. If both motors are drawing roughly the same amount of current (no more than 5% difference) then that should be fine. Otherwise you may need to PWM each motor seperately to ensure they share the load evenly.

Once you have that worked out then do the same on the right motors. Ideally both motors on either side should draw the same current. Once you've done that you can start writing code and using the encoders.

 

Looks pretty interesting, OddBot. Why do you describe the board for use with Omni or Mecanum wheels? Wouldn't it work just as well for any motor-driven wheel?

With the current sensing and encoder features of this board, you have a lot of capabilities!

G'day IG. True the board is suitable for any robot using multiple DC brushed motors. The motor driving circuit is the same used for Mr. Tidy which has 4 brushed motors.

I mentioned Omni wheels and Mecanum wheels simply because I thought that was the situation where most people will want to drive 3 or 4 DC motors.

In most other robots like the "Start Here" robot, only two motors are driven with "H" bridges and the rest of the motors are usually servos or occasionally steppers.

Before anyone starts nit picking (don't worry Rik, I won't mention your name :-)

Yes servos usually use DC brushed motors as well but they also include their own "H" bridge to drive them eliminating the need for this circuit.