ENGR 100: Robotics Design Project

Introduction:

This project involves working in teams to design and build a robotic wheelchair using LEGO Mindstorms Robotics Invention System to compete in an obstacle course.

Problem Definition:

The objective of this project is to build a computer controlled robot that can safely deliver an immobile person through an obstacle course in the shortest amount of time. To simulate real world situations, the robot must be able to climb a small ramp, cross a street without getting hit by a car, turn corners, fight off aggressive animals, climb stairs and free itself from a sandpit. Educational Goals: The goals of this project are as follows:

1. To provide students with hands on experience building a simple programmable robot.
2. To demonstrate that engineering projects typically involve a multitude of skills and knowledge from many subject areas.
3. To familiarize students with the design process.
4. To introduce students to the basics of computer programming.
5. To spark students' interest in Science and Technology.

http://www.plazaearth.com/usr/gasperi/lego.htm#background

http://www.oreilly.com/catalog/lmstorms/resources/index.html

http://www.robotbooks.com/

Obstacle Course:

The course is set up on a concrete floor as shown in Figure 1. The outer wall consists of two 2 x 4's stacked on top of each other. A 3" tall ramp is located immediately past the starting area, followed by a crosswalk through two-way traffic. A master controller (RCX which directs the traffic and robotic wheelchair) is located near the crosswalk. The next obstacle is a 180° turn at which point the robotic wheelchair encounters two defender robots. The robotic wheelchair must maneuver past these robots, climb and descend the stairs (¼" steps), drive through the sandpit, before reaching the finish line.

Figure 1. Obstacle Couse

Robot Constraints:

Size:

The maximum size of the robot must not exceed 12" by 12" by 12". Moreover, the robot cannot look over the walls of the structure and must never extend itself beyond 12 inches in any dimension. All robots will be carefully measured. Don't risk disqualification because your robot is slightly over the limit!

Weight:

There are no restrictions on the weight of the robot.

Function:

The robot must resemble a regular wheelchair. Additionally, it must be able to safely transport a passenger (will be provided). Robots whose passengers fall out will be disqualified.

Programs:

The robot must have three programs installed on the RCX:

Program 1 - Robotic Wheelchair

This program provides the navigation for the robot to maneuver through the obstacle course. In additional to clearing the obstacles, this program needs to ensure safe passage across the crosswalk. It does this by executing Message 1 (stop) and Message 2 (start again) sent from the Master Controller* when the robot reaches the edge of the crosswalk.

Program 2 - Car

This program causes the robot to behave as a car. A car is defined as a robot that moves forward and backwards across a narrow (4 ft) passage. Additionally, it needs to be programmed to stop for crossing pedestrians (like the robotic wheelchair) and start again. It does this by executing Message 1 (move away and stop) sent from the Master Controller* when the robotic wheelchair reaches the crosswalk.

Program 3 - Defender Robot

This program requires the robot to perform certain actions in attempt to disable competing robots. This robot can have any mechanism or electronic device that can prevent the robotic wheelchair from proceeding through the obstacle course. Additionally it needs to incorporate a value from a light sensor to keep it from entering the "defense free zone".

*The Master Controller is an RCX that is programmed by the instructor. It sends out infrared signals when the robotic wheelchair passes in front of its light sensor. The "signals" do not contain directions, but alert robots in the vicinity to review content coded on their RCX. Thus, you will need to program your robot to execute the messages. It will send out a signal for robots to execute Message 1 (Wheelchair – "Stop" and Car - "Move away and stop") and then wait several seconds before sending out Message 2 (Wheelchair - "Go forward").

Rules:

The following set of constraints must be adhered to during the implementation of your respective designs. If you need further clarification, ask before you implement!!!

1. Wheelchair or car programs that send out messages will be disqualified.
2. Robots must start from rest and cannot to be lifted off the course after starting.
3. No human intervention is allowed during the match.
4. Your machine must be self-contained and self-sufficient. In other words, it must provide its own energy. No "plug-ins" allowed.
5. Robots must be powered by an electric motor. No fuel engine or rocket propulsion is allowed.
6. Robots can be constructed with Lego bricks, or with any type of materials. The structure of the robot, including wheels and legs, can be strengthened or enhanced by any means. Unless otherwise stated, there are no restrictions on the types of motors to be used.
7. You may alter any Lego parts; however, all alterations and manufacturing must be approved by instructor.
8. Using homemade sensors or gadgets (without destroying the existing Lego parts) are encouraged. There are numbers of Lego Mindstorms related web sites that deal with homemade sensors (listed in the Procedure section).
9. The ambient light level in the contest area is impossible to determine until the actual day of the contest. Contestants will be given time on the contest day to make ambient light level readings if necessary to calibrate their robot. Overhead florescent lamps light the room.
10. If requested, all supplemental, unspecified parts (if any) that your design uses must be accordingly priced and approved by your instructor.
11. If requested, all parts used to build your robot must be itemized.
12. No competitor shall employ devices that compromise the safety of competition spectators or machines. Robots deemed unsafe will be banned from the competition. Unsafe machines will be permitted to re-enter after the unsafe feature is removed.
13. Weapons designed to temporally disable or topple other robots are allowed. However, the devices must be operated under the strict safety code as outlined in rule #11.. Devices using projectiles (tethered or otherwise), rockets, explosives, open flame, caustic chemicals, fluid or cut-off discs are strictly forbidden. BTW, Flying Robots are not permitted.

Scoring:

The final score will be awarded based on the following equation: