Source code can be found here http://github.com/mobilerobot-io/arduino/ within the src/mctl directory.
Arduino Motorsheild and Distributed Controls
The software in the repository is to be loaded on an Arduino with either an Adafruit v2 Arduino or OSEPP 6612 MotorShield. The software accepts commands as incoming text strings from one of several possible serial inputs; UART, RF Radio, Blue Tooth, etc.
TODO: place diagram showing an arduino accepting commands from a RPi
Input commands are parsed and the commands are acted on accordingly. For example, our SkidSteer provide the following throttle method to change the speed and direction of the vehicle.
I prefer to use an Arduino with a Motor Shield as a dedicated micro-controller regulating the voltage supplied to the DC motors, it may carry on local conversions or control calculations dedicated to proper motor handling.
Additional sensors and guidance inputs can be handled by additional, perhaps less critical controllers. Hopefully reducing the chance of critical motor controllers from failing.
The Big Skidder
My primary vehical is a 4wd, that is 4 DC motors directy spinning two rubber tires. I also have available two, two wheeled vehicals and a train tracked vehical.
In all cases each of these vehicle employ skid steering on account a one wheel (wheels or tread) will be skidding along when your turnin.
Required Motors and Controller
We need to power the following motors (at minimum):
- 4 DC Motors
- 2 Servos
The first phase of building Robots I recommend the Adafruit Motor Shield V2. I also tried the OSEPP 6612 and Adafruit Motor Shield v1 (before I realized there was a version 2).
Links to the shields can be found here:
- Adafruit v2 Arduino DC/Stepper MotorController
- [OSEPP v2 MotorController]()
Insert picture of Adafruit Motor shield
OSEPP Shields v1 & v2
The OSEPP MotorSheilds effectively duplicate the functionality of the Adafruite MotorShields.
The documentation is hard to find and must be pieced together through the documentation of their hardware kits. I do find the hardware to be of a sturdy make. The use connectors to help in learning, the Adafruit are more through for real prototyping.
For particular details about the controller and other hardware please refer to the Adafruit and respective product websites.
Arudio MCTL Software
The code in this library can be compiled by with the Arduino IDE to an UNO with an Adafrutit v.2 (or compatible) motor controller. One of the MBR vehicles OSEPP Two Wheel balancer uses an OSEPP motor library wich is very similar (but) different than the Adafruit version.
Reads From Serial Input
This could be virtually any “stream” of data from a UART, RF, Blue Tooth or Wifi ports. Regardless, the software reads from the appropriate input, parses the incoming commands and adjusts power to the motors accordingly.
Place snippet of Skidder software class here
MQTT and Motor Control Channel
Connect the motor controller to the MQTT control channel. NOTE: on vehicle may use the motor control channel when availble, however, must always be able to regain control (or shutdown completely) if the control channel has been lost.
Testing and Validation
How is this software tested and valided for promotion?
Todo document the testing procedure
Maintanance and Upgrades
Todo document the deployment and production release producedure.
Alas, too many projects, to little time!