Assembling the Chassis
First attach the Drive Motor Mount to the Chassis with eight 3/4 inch 8-32 bolts as shown below. Make sure that the large hole in the chassis is at the back of the robot.
Now drill the three holes in the Swivel Wheel Mount as indicated below using a 3/16 inch drill:
Then attach the Swivel Wheel Mount together with the Pi Mount Bracket using two 1-1/4 inch 8-32 bolts as shown below:
Next attach the three Motor Controller Mounts, two on the top and one on the bottom, using four 1/2 inch 8-32 bolts as shown below:
Next, attach the two Power Distribution Modules using four 1/2 inch 8-32 bolts. Place the red one on the left and the black one on the right as shown below:
Now attach the two Drive Motors to the mount using three 1/4 inch M3 screws. Be careful to not use longer screws as they can penetrate the gear casing far enough to interfere with the gears. Once you have attached the two drive motors, use zip ties to fasten the other end of the motors to the chassis as shown below:
Next attach the Swivel Wheel to the back of the robot using four 1/2 inch 8-32 bolts as shown below:
Now attach the wheels using two 6mm bore hex couplers. Then use a 1/4 inch M4 screw to attach the wheels to the hex couplers:
Now attach the Arduino Mount with two 8-32 bolts on the underside of the chassis in the position shown below:
Next we are going to attach the power wires that will connect to the battery. Cut a 14 inch piece of 16 gauge red and black wire. On one end, crimp U connectors that will screw into the power distribution module. On the other end connect the proper connector for the battery you have chosen. (In my case these are XT60 connectors):
Then feed the wire from the top through the large hole and connect the red and black wires the their respective power distribution modules:
We will now mount the first of 3 Step Up Regulators. Note that if you are using a 12v battery, this first regulator is not needed. In that case you should connect the battery directly to the motor controller.
Cut two pieces of red and black 20 gauge wire, one that is 6 inches, and a second that is 10 inches. Attach the 6 inch wires to the out+ and out- terminals on one of the Step Up Regulators making sure that the red wire is attached to the out+. Then attach the 10 inch wires to the in+ and in- again making sure that the red wire is attached to the in+:
Now using a zip tie, mount the voltage regular on the back of the right top Motor Controller Mount. Make sure that the voltage adjust potentiometer knob is pointing up.
Now route the input wires to the positive power distribution module on the left and the negative power distribution module on the right. Cut off any excess wire and then crimp both the positive and negative wires with a U shaped connector and screw them into the power distribution modules:
Connect a voltmeter to the output wires of the Step Up Regulator and connect the battery and reset the Circuit Breaker. With a small screwdriver adjust the little potentiometer on the regulator until the voltmeter reads about 12.5v and then disconnect the battery.
Next mount the Motor Controller using two 3/8 inch 4-24 sheet metal screws as shown below. Run the output wires from the regulator underneath the motor controller and screw the red and black wires into the terminal block as shown. Take note of the polarity and attach the red wire to the right and black wire to the left as shown below:
Now repeat this process with the second Step Up Regulator and attach it to the left top Motor Controller Mount. This regulator will be used to control the voltage for the LED light on the camera which requires 10.75v. If you are using a 12v battery then this regulator needs to be replaced by a step down regulator to supply the needed 10.75v.
After you have attached the regulator and connected it to the Power Distribution Modules, connect the output to the voltmeter, connect the battery and then adjust the output voltage to about 10.75v. This is the voltage that the camera LED requires and if you use a much higher voltage the LED will overheat.
Now mount a Motor Controller using two 3/8 inch 4-24 machine screws and connect the output from the regulator taking care of the polarity as shown below:
Now set up the third Step Up Regulator and mount it along with it’s Motor Controller on the underside of the board. Set the voltage of this regulator to 12.5v, the same as the first one:
Next attach the Auxiliary Arduino Board to the Auxiliary Arduino Mount using three 3/8 inch 4-24 machine screws:
Now connect the red and black power wires from each of the drive motors to the Motor Controller on the bottom of the robot as shown below:
Note that the motor to the left in this picture is connected to the leftmost output of the motor controller, and the motor on the right is connected to the rightmost output of the motor controller.
Now we are going to connect the wires from the two drive motor’s quad encoders to the Auxiliary Arduino. First crimp Male Crimp Connectors to the Blue, Yellow, Green and White wires from each of the two motors. Then insert the Blue, Yellow and Green connectors into a 2×3 housing as shown below:
Take care to make sure that the wires are inserted in the proper order with the wires coming from the left motor (as shown in the picture above) going to the left most 3 slots of the connector when viewed as above. The wires coming from the right motor should go to the rightmost slots.
Now connect this connector to the Auxiliary Arduino as shown below making sure that the yellow wires are closest to the Arduino:
Next, insert the White wires from the two motors into a 1×6 housing as shown below:
Note that the white wire from the left motor is to the left of the white wire from the right motor.
Now use a 4 conductor piece of 20 cm male to female Dupont Jumper Cable and place the male connectors into the 1×6 housing that has the two white wires from the motors, and place the female connectors into a 1×4 housing as shown below. The color of the wires you use is not important, just be sure that they are in the same order for both connectors (in my case blue, green, yellow and red).
Then attach the cable from the Auxiliary Arduino Board to the Motor Controller on the left. Take care to be sure that the order of the wires are the same for both connections: