What I need to build a mini 3pi robots lab

Robotics and electronics discussion Wireless and radio
1

Dear All,
I would like to build a multi-robots mini lab, where I use the 3pi robots as my individual agents. In the end, I would like to be able to send the speed commands over a wireless communication from a remote computer running (matlab, or ROS) and at the same time to receive the measured robot wheels’ speeds over the same connection. For the localization purpose I will be having a separate tracking system to use… To this end, I would like to know if this would be possible by the products provided by Pololu, and, if yes, then what would be the components I need to purchase per each mobile agent.

Any experience to share is more than welcome!

All the best,
Mohamed

2

Hello, Mohamed.

We have some wireless solutions that can be used with the 3pi. The m3pi expansion kit makes it easy to integrate modules like the XBee and our Wixel programmable USB wireless module. You can read more about using these devices with the m3pi as a wireless interface in the “Using the m3pi” section of its user’s guide.

You might also find the example serial slave program for the 3pi helpful for controlling the 3pi using another device. It allows for control of various features of the 3pi through the TTL-serial port. You can read more about it in the “Serial slave program” section of the 3pi user’s guide.

- Jeremy

3

Hi Jeremy,
Thank you very much for your prompt reply… Then, to build one robot and have it running via wireless communication, I need (a 3pi robot, an m3pi expansion kit, and a wixel programmable USB wireless module… right? )

I still would like to emphasize my question about (reading the current speeds of the robot wheels and feeding them back through the wireless module)… Is it possible for 3pi robots to read their wheels speeds’ measurements?

Thanks a lot in advance!

All the best,
Mohamed

4

Those parts should work well together. Please note, you will need two Wixels in your system for wireless control.

For measuring the motor speed, you will need to add encoders to the 3pi. The 3pi does not directly support encoders, but some of us have been able to add encoders to the 3pi and posted about it in this thread. If you add encoders to your 3pi, you might be able to read them using the Wixel; however, it will probably be easier to use a different microcontroller, like our A-Star microcontrollers, to read the encoders and calculate the speed and have the Wixel as a dedicated device for wireless communication.

- Jeremy