The purpose of our project and robot was to find a way to construct a robot that could pull the most weight in the least amount of time. We took aerodynamics, weight, and structural support into consideration and built what we thought to be the most effective robot possible.

Step 1: Building the Sled: Assembling the Sled

Assembling the Sled
- (1) Plate
- (5) Bearing Blocks
- (10) 0.318" (8.1 mm) Plastic Spacers
- (10) 8-32 BHCS x 3/4" (19.1 mm)
- (10) Keps Nuts

Step 2: Building the Sled: Attaching the Hitch

- (1) 9-Hole Long Bar
- (1) 5-Hole Angle Bar
- (2) 0.182" (4.6 mm) Plastic Spacers
- (2) 8-32 BHCS x 1/2" (12.7 mm)
- (1) 8-32 BHCS x 1/4" (6.4 mm)
- (3) Keps Nuts

Step 3: Building the Sled: Adding Weight

- (2) 8-32 BHCS x 1/4" (6.4 mm)
- (2) 2" (5.1 cm) Threaded Beams
- (2) 5lb (2.3 kg) Weights

Step 4: Building the Robot:

1) Take rack off
2) Take off front bar
3) Take off bumper
4) Attach controller on 4th hole starting from the back and use 4 8-32 3/4" screws (one in each corner of the controller) and use 4 keeps nuts to tighten the screws
5) Attach a 9-hole long bar to the 2 inner chassis rails on the back use 2 8-32 3/8" screws and tighten with keeps nuts
6) Grab 6 4-hole long bars and 12 8-32 1/2" screws and grab 12 keps nuts
7) Put 1 4-hole long bar to the front 2 holes on the left sat of chassis rail
8) Do the same to the right set of chassis rails
9) On top of the left set of chassis rails put another 4 hole long bar
10) Do the same to the right set of chassis rails
11) Count 3 spaces from those 4-hole long bars and add another 4-hole long bar on both sides
12) Screw the long bars at the extremities with the screws mentioned and tighten with the keps nuts
13) Take the back wheels off

Step 5: Building the Robot Continued

14) Take the current gear on the back wheel off and replace it with a 64 tooth gear on both sides
15) Take the current gears on the motor and replace them with 36 tooth gears on both motors
16) Attach 1 knobby wheel to each side then secure them with one collar shaft on the end of each wheel
17) Take the front wheel off and everything with it
18) Get a 5” square bar and 4 shaft collars
19) Put 1 shaft collar through the left side of the bar
20) Grab a 100mm wheel and put it through the right side of the bar
21) Put 1 shaft collar through the right side of the bar
22) Now center the wheel and put the shaft collars as tight as you right next to the wheel
23) Take this and put one side of it through the first bottom hole of your left inner chassis bar
24) Take the other end and put it through the same hole on the opposite side
25) Grab 2 remaining shaft collars and put 1 on each side of the square bar and tighten so that it has minimal movement from side to side
26) Attach worm gearbox with 2 8-32 3/4" and 2 keps nuts to the 9 hole long bar 1 hole from the screw on the left, in order to place the battery in

Step 6: Gear Ratio

a.) The gear ratio is 9:16
b.) We changed it to optimize the balance between torque and speed.
c.)The input RPM is 121.82 RPM and the output RPM is 68.52 RPM
d.) The input torque is 1.67 n•m and the output torque 2.97 n•m

Step 7: Wheel Size

The theoretical speed is 46.6 cm/s
The actual speed is 30.21 cm/s

Step 8: Design

(Proposal Sketch above)
First we took the rack, front bar and back bumper off to decrease the weight and make the robot more aerodynamic. We changed the back wheels from the 70mm wheels to the 130mm knobby wheels to increase speed. We changed the middle wheel to 100mm wheels to keep the robot balanced and increase speed. We changed the gears to 9:16 to increase torque.We added the various long bars because we still needed structural support and the long bars are less weight than the front bar and back bumper. Therefore this made our robot steady as well as less weight, and allowed for us to have a bigger wheel in the front.