Line Follower Robot: Detection Scenarios

Robotics Project Framework

• Any robotics project has 2 steps: detecting/sensing a condition, and deciding how to react based on the detection.
• The robot performs the detection and reaction steps in a loop.

Detection Step for Line Follower

• The quad RGB sensor has 4 sensors: 2 left (L1, L2) and 2 right (R1, R2).
• The robot can detect which side of the line it's on, based on the sensor readings.
• There are 4 scenarios: Line sensed only by right sensors; Line sensed only by left sensors; Line sensed by both left and right sensors; No sensors detect a line.

Scenario Details

• Scenario 1: Right sensors detect line, robot is too far to the left.
• Scenario 2: Left sensors detect line, robot is too far to the right.
• Scenario 3: Both left and right sensors detect the line.
• Scenario 4: No sensors detect a line, robot is not on the line at all.

Truth Table Mapping

• The truth table maps sensor values to detection scenarios.
• Decimal value 0 (L2, L1, R1, R2 all 0) corresponds to scenario 4 (no line detected).
• Values 1, 2, 3 (only right sensors detect line) correspond to scenario 1
• Values 4, 8, 12 (only left sensors detect line) correspond to scenario 2.
• Other Values (combinations of left/right sensors) correspond to scenario 3.

Detection Logic: Scenario 4

• If the sensor value is exactly 0, then it is scenario 4.
• In the block program, this can be handled in the "if" branch of an if-then-else block.
• The remaining logic should be placed in the "else" part of the block.

Detection Logic: Scenario 1

• Decimal values less than 4 (1, 2, 3) indicate scenario 1
• The decimal values represent when only the right sensors detect the line.

Detection Logic: Scenario 2

• Values 4, 8, and 12 correspond to scenario 2
• These values are all multiples of 4 between 4 and 15.
• Modulo operator (%) gives the remainder of a division.
• If a number is a multiple of 4, then number modulo 4 equals 0

Detection Logic: Scenario 3

• All remaining sensor values (other than those for scenarios 1, 2, and 4) are mapped to scenario 3.

Reaction Logic: Scenario 4

• No line is detected, robot turns left.
• If starting off the line, place the robot to the right side of the line.

Reaction Logic: Scenario 1

• Line sensed only on the right, robot turns slightly right to center on the line.

Reaction Logic: Scenario 2

• Line sensed only on the left, robot turns left to center on the line.

Reaction Logic: Scenario 3

• Line sensed by both left and right, no correction needed, robot continues forward.