Line Following Lets review portions of Line Following

Line Following • Let’s review portions of Line Following Exercise. • First we used “bang-bang” control to follow a line’s edge (right side and left side). • Then we got both motors going by using hysteresis (transition overlap). • Let’s introduce proportional control by using the motor() function. motor (motor # , percent full power); We might achieve smoother transitions.

Follow Left Edge of Line Definitions White = 25 Black = 125 port_motor = 1 Buggy starboard_motor = 3

Control Strategy Plot

Pseudo-code sensor = analog(3); /*read the sensor*/ If (sensor < 75) { pmp = 100; /*set port motor power*/ smp = 0; } /*set starboard motor power*/ else { pmp = 0; /*set port motor power*/ smp = 100; } /*set starboard motor power*/ motor (port_motor , pmp); motor (starboard_motor, smp);

Follow Right Edge of Line Definitions White = 25 Black = 125 port_motor = 1 Buggy starboard_motor = 3

Control Strategy Plot

Pseudo-code sensor = analog(3); /*read the sensor*/ If (sensor < 75) { pmp = 0; /*set port motor power*/ smp = 100; } /*set starboard motor power*/ else { pmp = 100; smp = 0; } /*set port motor power*/ /*set starboard motor power*/ motor (port_motor , pmp); motor (starboard_motor, smp);

Follow Left Edge of Line (Get both motors going with hysteresis) Definitions White = 25 Black = 125 port_motor = 1 Buggy starboard_motor = 3

Control Strategy Plot

Pseudo-code sensor = analog(3); /*read the sensor*/ If (sensor < 50) { pmp = 100; /*set port motor power*/ smp = 0; } /*set starboard motor power*/ else if (sensor > 100) { else pmp = 0; /*set port motor power*/ smp = 100; } /*set starboard motor power*/ { pmp = 100; smp = 100; } motor (port_motor , pmp); motor (starboard_motor, smp);

Follow Left Edge of Line (Use proportional control for smooth transitions) Definitions White = 25 Black = 125 port_motor = 1 Buggy starboard_motor = 3

Control Strategy Plot

Pseudo-code sensor = analog(3); /*read the sensor*/ pmp = 100 -1 * (sensor – 25); smp = 1 * (sensor – 25); motor (port_motor , pmp); motor (starboard_motor, smp);

Follow Left Edge of Line (Get both motors going with hysteresis) (Use proportional control for smooth transitions) Definitions White = 25 Black = 125 port_motor = 1 Buggy starboard_motor = 3

Control Strategy Plot

Pseudo-code sensor = analog(3); /*read the sensor*/ If (sensor < 75) { pmp = 100; /*set port motor power*/ smp = 2 * (sensor – 25); } else { pmp = 100 -2 * (sensor -75); smp = 100; } /*set starboard motor power*/ motor (port_motor , pmp); motor (starboard_motor, smp);

Proportional Control (Careful algebra can avoid floats. Save the divide for last. ) Definitions White = 25 Black = 100 port_motor = 1 Buggy starboard_motor = 3

Use Careful Algebra (y = mx+b) to Avoid Floats Inside parentheses executes first – save the divide for last

Pseudo-code sensor = analog(3); /*read the sensor*/ pmp = (100 * (sensor – white)) / (black – white); smp = 100 - pmp; motor (port_motor , pmp); motor (starboard_motor, smp);