NOTE: I found that other people such as +Virgil Machine were having good results with just a diode across the coil. Here is a link to his blog page. That didn't work for me possibly to due the relay that I use.
Next I'll mounted the perf board (I used the handy half-size perma protoboard from Adafruit for this which I picked up for 4.95 euro) and the battery on the cart. I connected the the motor, battery and switches to the perf board. Then it was time to test the cart. The first test went miserably because the cart didn't react to the switches. I then connected my bench power supply to the cart and it worked fine. I figured that the capacity of one block battery is insufficient to power the cart. I solved this by placing two block batteries in parallel which doubles the capacity of the power source.
|Testing the nearly finished cart with two block batteries in parallel. The block batteries are connected with alligator clips. The higher capacity was needed to power the circuit and the motor (which is very power hungry).|
With the power problem solved I made the last additions to the cart. I added an on/off switch and a glued a piece of plywood with velcro on it to the back of the cart. I attached the two block batteries to the velcro. Lastly I glued rubber to the front wheel to get more grip.
While testing the cart I noted that it runs way to fast. I already damaged a sensor when cart hit a closet. Also the alligator clips come loose when the cart hits something. Nevertheless I feel I have nearly completed this experiment. I'll probably replace the motor for one with lower RPM (and a less power hungry one).
|The perf board attached to the top of the cart with two bolts and nuts. Note the two diode are added to the circuit.|
|It doesn't look pretty with all those wires but it works. The batteries are attached to the cart with velcro.|
|Side view of the robot cart. A piece of plywood is added to the back of the cart to accommodate the batteries. I glued rubber to the front wheel of the cart to increase traction.|
|The other side of the finished robot cart.|