Soccer Playing RC Car
*Won first place in CSU ASME Competition*
The Soccer Playing RC Car is a personal project that myself and three other students took on for a competition that the American Society for Mechanical Engineers (ASME) club hosted at CSU. I decided to sign up because I wanted to gain more hands on experience with Arduino, programming, and electrical wiring and thought this would be the perfect opportunity to learn more about it.
GENERAL RULES
The general rules that we were provided have been summarized below. For a more comprehensive set of rules, the rulebook for the competition can be viewed here.
Robot Constraints
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1. At the start of the competition, your football squad (all robot devices and controls, any extra batteries, and any tools your team would use to make minor repairs during the competition) must fit within a rigid sizing box that is no more than 50 cm x 50 cm x 50 cm (internal dimensions). Your football squad will be sequestered inside your sizing box throughout all of the rounds of the competition. Teams will have one minute to prepare your device(s) to compete in each round after removal from the box.
2. All energy for the device must be provided by rechargeable batteries. Teams may replace batteries between rounds, however replacement batteries must be identical to the original and mounted in the same way to the device.
3. Your device or devices must be controlled either via remote control through a transmitter/receiver radio link or through an umbilical cord.
4. Flying devices are not allowed. Devices must remain intact throughout the game (for example, a part of the device may not be fired at a ball).
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Playing Arena
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1. The playing surface dimensions are 5m x 5m, with boundary wall barriers that are at least 8 cm tall. Goals are 50 cm wide by 50 cm high, located in the center of each side of the playing surface. A 50 cm x 50 cm penalty box in front of each goal will be marked by tape on the ground.
2. The playing surface will be level, and may be either hard surface or carpet typically found in public areas.
Gameplay Rules
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1. At the start of each game, the four teams will be randomly assigned a color (blue, red, green, or yellow) for that round. The color determines the goal the team is defending and the points that will be earned for each goal scored.
2. At the start of each game, the four teams will be randomly assigned a color (blue, red, green, or yellow) for that round. The color determines the goal the team is defending and the points that will be earned for each goal scored.
3. Games consist of two 5 minute halves. At the start of the 1st or the 2nd half of each game, eight tennis balls (two balls marked with each of the four colors) will be placed on a 1m x 1m square marked by tape on the ground. All teams’ devices will begin both the 1st the 2nd half of each game within the penalty box that is their designated color for that game.
4. All the teams’ devices will attempt to gain control of the balls and score goals in any of the other three goals that are not their team’s designated color. A team scores a goal when a ball that they control and propel goes into another teams’ goal.
5. Teams will earn points for goals scored against the other teams as follows:
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five points for scoring with a ball into the same color goal
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two points for scoring with a ball into a different color goal
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shot that deflects off another team, into a goal counts as a goal for the original team controlling and shooting the ball
6. Teams lose one point for every goal scored in their own goal. This includes deflected or own-goals.
DESIGN
After considering the rules of the competition, the team decided that a Bluetooth remote controlled car with an outer shell to push the ball around would be the most reliable approach. Below is a list of parts that were used:
Wheels x4
TT Gear Motors x4
HC 06 Bluetooth Module x1
Lipo Battery x1
Chassis Frame (3D printed) x2
9v Battery x1
Arduino Uno x1
L298N Motor Driver x1
With just these parts, the team was able to build a very basic remote controlled car. These particular motors were chosen because of their low cost and durability, however it should be noted that they do not have speed control capabilities. The four TT gear motors were glued to one of the 3D printed chassis frame parts and the wheels were inserted onto one axle of each motor. The second chassis frame part was adhered to the top of the motor, leaving the entirety of its top surface for the electrical components. To finish, an outer caging made of heavy duty wire was installed around the entire car and another scoop shaped bumper was mounted to the front to push the ball around.
The wiring diagram for the electronics can be viewed below. As previously mentioned, these were all mounted to the top of the chassis frame, which allowed for easy access in case items needed to be replaced or batteries needed to be swapped out and charged.
Next, a code to control the electrical components was written using the Arduino interface. The Bluetooth module was connected to a phone application, allowing the motors to be conducted by the user through the phone. Since we were working with very simple motors, the turning function was slightly tricky to implement. In order to overcome this, we were able to control the power allowed to specified motors through the H-bridge in the motor driver. Certain commands on the phone application were designated to different motors being turned on and off. For example, to turn right, both motors on the right hand side of the car would be turned on and both motors on the left hand side of the car would be turned off. To move forward, all motors were to turn in the clockwise direction and to move backward, all motors were to turn in the counterclockwise direction.
THE COMPETITION
On competition day, there were 5 other teams competing in the tournament. Right before the competition started, an axle on one of the motors broke off. Unfortunately, the team did not have time to replace the motor entirely, therefore we had to resort to gluing the axle back on, which proved to be a short-term solution - during one of the final matches, the wheel popped off, seen in one of the following videos. Although this obstacle presented a challenge to the team, the RC car built by my team was superior in speed and control compared to the robots built by other teams. Because of this, we still ended up on top by scoring far more goals than any of the other teams, winning the competition in the end.