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4.2 Project Details
As concluded by J. Buhmann at al. [3] a robot must solve each of the following tasks to achieve the overall goal:
- Map building
- Motion planning
- Collision avoidance
- Localization
These tasks have been implemented separately and in the given order but for the localization function(omitted because of lack of time).
The program was elaborated through foollowing stages: Explorer#1, Explorer#2 and Explorer#3.
Robot building
A robot deemed fit for the needed requirements was constructed. Figure 2.2 shows an image of our fancy robot.
| Figure 2.2 |
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Explorer#1
Tasks solved:
This program rotates its head 360° while converting the polar readings (angle head, ultrasonic distance) into cartesian coordinates that allow saving in a 2-dim array. The robot then travels forward 5 cm and repeats the first step and so on. Figure 2.3 shows a functional flowchart of Explorer#1.
| Figure 2.3 |
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Explorer#2
Tasks solved:
- Motion planning
- Collision avoidance
- Start positioning
The main idea here was to explore the room in a clockwise direction by always following the wall on the left side. Once the robot reaches the position it originated from the program stops. Figure 2.4 shows a functional flowchart of Explorer#2.
| Figure 2.4 |
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Explorer#3
Tasks solved:
- Map building ¹
- Motion planning ¹
- Collision avoidance ¹
- Start positioning ¹
- Measure environment (light, noise)
- Course correction
- Exit condition
- Save map to Targa (TGA) [4] image format
¹ task solved before
The formula used to determine the environmental quality is:
q = (100 - noise + light)/2 q ∈ (0, 100)
Course correction is implemented through a FIFO buffer that stores and compares the actual and the past 3 distances to the wall on the left side. When too many values in the buffer differ from each other a course correction is executed. The exit condition uses a defined start area, once left the program exits if the current position is within the starting area. The map is finally saved to a Targa file. Figure 2.5 shows a functional flowchart of Explorer#3.
| Figure 2.5 |
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