For my unofficial contribution to the Picasso Design Challenge I am planning to create a holonomic mobile robot which is one which can move in any direction but always maintains the orientation. To do this I am planning to put a step motor on each corner of the chassis. The four step motors will be calibrated to always point in the same direction and then will always move the same number of steps. In this way, hopefully, they will always all be pointing in the same direction. On the shaft of each step motor I will fix (somehow!) a continuous rotation servo motor. I could use DC motors but the servo motors have gearing so should produce quite a high torque, ,which will be needed to move the display I plan to use. If the system cannot move a full size flat screen monitor then I will get a smaller and lighter TFT or LCD display.
I have purchased the step motors and continuous rotation servo motors so now I am designing and implementing one of the corner drive mechanisms. The first thing I have done is just to get one of the step motors rotating as I haven't used this step motor or driver board before. I purchased a nicely boxed set of five step motors with accompanying drivers (based on the ULN2003) and some Dupont interconnection wires from Elegoo. They came quickly and in a nice box.
I am using an Arduino Nano for this initial testing phase as I am not familiar with the Raspberry Pi yet so that I can be sure all the hardware is working. I wrote my own programme which just outputs a pulse in sequence to each of the four phases, A, B, C and D. I tried using the example Step motor programme provided with the Arduino IDE but it didn't work and I couldn't be bothered to work out why. See below:
The next step will be to design the 3D printed widget that will connect the continuous rotation servo motor to the shaft of the step motor. Shold be fun.
Dubbie
Top Comments