I have a toy car that I wanted to make autonomous.
It has a motor for rear drive (seen in the bottom of the photo hidden in the gear-box) and a motor for rack and pinion steering (located just above the webcam in the photo). Reversing the polarity allows the car to reverse, as well as steer in the opposite direction.
I have successfully added break out cables from these two motors, hooked up in addition to the toy's original wires to them. These cables (red/black for drive motor and light/dark green for steering motor in photo) have been hooked up to an Arduino. I was able to control both motors with relative ease using Node.js.
However, the toy car has four 1.5v batteries to power it. When I check how much power arrives at the motors using the Arduino, it's under 1v, and the toy car can't drive when placed on the ground, nor can it steer the wheels (I just hear a click and see the rack move about 1mm each way).
If I check with a multimeter, the lines seem to get ~5v, but once they're connected to the motors, they drop to under 1v.
I tried desoldering the original lines that went from the car's PCB to the motors, but it didn't seem make a difference. If I use the car's original remote control, the wheels fly along and receive the normal ~5v.
I am wondering if it's possible to use relays to let the Arduino control the switching and polarity, but have the car's original power source provide the final power. I'm aware how relays work, but I'm curious if they're compatible with requiring the polarity switch. If it's possible, would I need special relays or just one of the normal Arduino ones?
In case you couldn't tell, I'm new to Arduino, with this as my first project.