Robots are known for their different power units for the movement. I built a bot with four special mecanum wheels. Robots using mecanum wheels are able to drive in any direction on the ground. Such a bot is able to strafe from one side to another, to drive a circle, back/forward, turn on the spot or just a curve. Each wheel needs a separate dc motor which is controlled independent to each other. To control the DC motors I installed a Raspberry Pi computer in my robot. I wrote the Python programs I need to control the bot by myself.
To control the four DC motors separately I installed two motor drivers from the type L298N in my robot-car. This design enables me to control each motor separately with the Raspberry Pi and the self-written Python programs. The following picture shows the robot with the two motor drivers in the back (right) of the robot.
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Controlling the mecanum Raspberry Pi robot:
To control the bot I wrote two Python programs. The first one is developed to control the two motor drivers installed in the bot. The second one reads the inputs form the user and controls the movement of the bot like the direction and the speed of the robot-car. Both programs together are enabling the user to control the robot.
Very difficult is the steering of the bot during driving along a curve and then change the direction and let the robot strafe maybe to the left. The user has to change the steering by changing the speed of each dc motor and the program has to manage the transition from a curve movement to a strafe movement of the bot. The nice part of this difficult driving maneuver is that you do not have to change your hardware setup. The only thing you have to do is to change your program because all the movements are controlled from a Python program.
Everybody who wants to see the program could donwload the program from my website.
VIDEO MECANUM ROBOT:
The video shows the first tries to let the robot strafe from one side to another. It is not too easy because of the manual steering with the keyboard. Please don’t be surprised if the result of my driving maneuver is not perfect at all.
Raspberry Pi robot-car component list:
If I could awaken you interest how to build such a robot with a Raspberry Pi computer as central controlling unit you will find a list of components on my blog to help you. The component list is an overview of electronic components or ready to assemble kits which I used by myself and which I could recommend with good conscience. I used most of the components in my own projects and checked the functionality and compatibility with a Raspberry Pi.
This is the link to the component list: component list
The mecanum wheels just do not only look interesting, they enable the bot to drive special driving maneuvers which are not possible with normal wheels. To develop the Python program to control the robot with the mecanum wheels was not easy. After a few reflections how the control program could look like I started with the development. After a few training round in my office the mecanum car makes a lot of fun.