This is how to build an omnidiretional car, that will follow your hand as you move it above the car. The file "3d prrint omni-bil" is a 3D print, for the frame of the car. The file "omni-car" is the code for your arduino board. In the code there is a constant called "a". Depending on your motor you will need to recalculate this value. It is calculated by dividing the amount of steps needed for one full rotation, by 360. Futhermore the "b" constant is needed if your motor has some "dead time" whilst starting. It should be noted the motors used here where of suspect quality, therefor the "b" value is quite high and the program is a bit untested. The individual parts work but the motor used for direction was to unreliable to proberly test.
For this you will need:
1 arduino bord
2 stepper motors of your own choice
2 DRV8825 stepper motor drivers
2 HC-SR04 ultra sound sensors
M-M and F-M conector cables.
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Step 1: Step 1: Attach the Sensors
once everything is 3D printed grab the box, and two long sticks. Firmly attach the sensors on the raised part end of the stick. Slide the splitted end on to the box. For the wiring of the leftmost sensor, attach the VCC to 5v, the gnd to ground, trig to port 3 on your arduino and echo to port 4 on your arduino. Wire the other sensor to port 5 for trig and port 6 for echo.
Step 2: Step 2: Asseemble the Wheel
Place a rubber band on the wheel to give it traction. Then put the wheel carefully in the holder. Make sure the hole for the axis is on the same side as the mount for a motor. Attach the motor securly to the side of the wheel. Wire the motor up to the driver. The dir pin on the driver needs to be wired to port 10, and the step pin to port 11.
Step 3: Step 3: Attach the Diretion Motor
insert the other motor in the 3D printed box. Make sure to securly mount it. Wire this motor to the other motor driver. This drivers step pin needs to be wired to port 9 and the dir pin to pin 8 on your arduino board.
Step 4: Step 4: Assemble the Rig
The two parts shown in image one are the buttom part of the car. The legs of the buttom, needs to be sawn down to size. They are to long on the model incase the rubber band on the car is to fat. Cut the legs so the wheel is in contact with the ground. Place wheel and holder in the part with three legs. Slide the other part on top, such as the wheel is held in place. The bulbus part of the wheel holder axis needs to be on top of both parts. finally slide the bottom part into the bottom of the box. Take a M-M wire, or a button, and plug it into port 7. Place the other end of the wire in a ground connetion. To start the car, remove this wire and hold your hand above the car for 5 seconds. The car should now follow your hand. Do note port 7 is in pullup mode, meaning if you dont put in a wire it will always be triggered. When it is connected to ground the car will effectively be in "standby" mode.