Autonomous Map Guided Robot

The autonomous map guided robot is a robot project implemented using iRobot Create and mbed chip. The idea of the design is to implement a self-navigated robot without a GPS or a white line on the floor. Using ultrasonic sensors, the robot is able to move along a hallway and make turns at ends of hallways. A user defined map is stored within the program before the robot is started. The robot will make correct turning decisions at the end of hallway according to the map. By using the map, the robot will also realize its arrival at the destination.

mbed Peripherals

• Three LV-MaxSonar-EZ analog ultrasonic sensors
  • Distance sensors used to detect walls on both sides and the end of hallway in the front.

• Voltage regulator
  • Used to provide stable 5V power to the mbed chip and the ultrasonic sensors. Since the sensors require a total of 300mA current draw, a voltage regulator or an external power source is required.

iRobot Create

• A creative robot controllable through serial interface
• For more information, please see the following link: https://mbed.org/cookbook/iRobot-Create-Robot

User Instructions

• 1. Change the map array: arr[] to store your map into the program
• 2. Put the robot at the starting point
• 3. Press the power button on the robot and wait for the robot to navigate by itself
• 4. When the robot stops and plays music, the destination is arrived

Connection

Left ultrasonic sensor

Right ultrasonic sensor

Front ultrasonic sensor

mbed connect with iRobot Create

Power connections

Program

Problem encountered

We spent most of the time solving power issues with the robot. First we realize that the sensors draws too much current from the robot, which cause the robot unable to sustain a stable voltage. Then we find out that the battery of the robot is too old and we had to replace it with a new one. At the beginning of the project, we were thinking about using a digital compass for navigation. However, after a few tests, we realized that the magmatic field generated by nearby electronics is too powerful and the reading can be off by 100 degrees for several seconds. Considering it is very hard to distinguish between the influenced readings and the regular readings, we decided to use the ultrasonic sensor along. A range finder can be helpful when detecting corners of the hallway, but since the ultrasonic sensors work well in most of the situations, we decided to use the ultrasonic sensors only.

Future Works

Range finders can be added to achieve more stable performance at corners. GUI can be developed to help users to generate maps for the robot.

References

https://mbed.org/cookbook/iRobot-Create-Robot