Design Problem:

Design a chassis and drive train for a mobile robotic system capable of pulling as much weight as possible. Your chassis should be designed so that it is easily adaptable to other applications.

Criteria:

• Each team member must contribute a possible design be for their team begins building their robot. Designs may be documented through a technical drawing or a CAD model.

• Chassis should have room for additional end effectors located in the following places:

  • At the front of the robot, center to the chassis.

  • Centered in the drive axle of the robot.

• Maximum towing weight will be calculated by the maximum weight the robot can pull 5 feet in 10 seconds.

• Chassis should secure microprocessors, batteries, wires, etc so that they do not interfere with the operation of the robot.

Constraints:

• Chassis should be less that 14"x14"

• Robots may use hardware and 3D printed components pending approval from Mr. Hansen

• At this stage your robot may be remote controlled or autonomous.

• 2 and a half weeks weeks time constraint

Brainstorming, Technical Drawing, and Final Prototype Images:

Design Process:

To begin, we surveyed our robotics parts so we knew what materials we had to work with. After brainstorming ideas, we decided to use the tractor wheels for increased traction and strength. We started construction by building the basic metal frame. We used the mounting kits to attach the motors. We then attached the front wheels of the robot but were unsure of how to connect the tractor wheels. We solved this using two 3D printed pieces. Next we put the electronic parts on the robot by adding three more metal pieces. We used the instructions book to hook them up to the battery so our robot turned on. We used zip ties to secure our wires. Next we entered our code into the motor controller so our robot would drive. We then tested our chassis and discovered it was too back heavy and it flipped. To fix this, we attached another chassis piece to put a piece of wood in for extra front weight. We also added a 5th wheel to the back. We then improved our design in the extra time by adding a gear in between the motor and the wheel.

Evaluation:

Our choice of wheels which is tractor wheels was not as effective as we originally had thought. Since they have such a large diameter, the wheels had less rotations so it did not accelerate very fast. Also the wheels tilted inward while it was being driven. We were about middle of the class in the battles. Our max weight was 15 on a sled without wheels.

After our revision of adding gears, we could pull 22.5 pounds in 10 seconds. This is our max weight. Our torque increased. Adding gears wasn't as effect as we had anticipated for the battles because we did not have time to perfect them. The wheel speed was also further reduced which made our acceleration even slower.

Our robot exceeds the competition in aesthetics. Our robot has actual tractor wheels.

Improvements:

• If we added more gears to our robot, our robot would have more torque.

• By using regular wheels instead of large, tractor wheels, our chassis wheels would have more rotations and therefore a greater speed, which is already slowed with gears. The traction of the wheels to the ground would also increase so we could out pull the competition.

• The tires on our robot were uneven so our robot drifted and the wheels turned in. Straitening these out would have increased both the efficiency and control of the robot.

• Using four motors instead of two would have increased the power of the robot.

• We could have used a line guide to help our robot drive straight.

• Putting more weight on the front of our robot would keep it from flipping over and allow it to be pulled back less easily by the competition.

• If we had made our robot smaller, it would more stable so it does not drift and dip.

• We could also make our chassis taller and steeper and make it front wheel drive so it does not flip. This design proved to more weight during the competition.