Build O_robot DiffDrive on TI-Driver level + sysconfig

[davidzwa]

Goal:

Calibrate tachometers together with setting 'millimeter per second' speed of wheels. Integrate with differentialDrive calculations to drive robot straight ahead.

Formulas:

• Interrupt edges per REV: gear_ratio * tacho_lines = 120 * 32 = 3840 My TICKS_PER_REV define https://github.com/davidzwa/advanced-iot-lisat/blob/dc2fbd62b001cd7e7f69eb4d5c7fa3c4a3760171/src/MSP432LISAT/MSP432P401R_LISAT_ccs/Robot/robot.h#L18 Seems to mismatch with O_robot (https://github.com/amjadmajid/O_Robot/blob/d5debd43177ae3c0aecf9000c0d1a12346192689/RobotModel/include/differentialRobot.h#L13)

• Wheel circumference: pi * diam = pi * 70mm

• Distance per rising edge (interrupt): wheel_circumference / interrupt_edges_per_rev

• Delta distance (tacho): num_interrupts * distance_per_risingedgeinterrupt

(Pinout config from O_robot):

• P1_6, P1_7 are motor direction
• P2_6, P2_7 are power (pwm?)
• P3_6, P3_7 control sleep

[davidzwa]

CCS10 graph of the interrupt time-difference (in timerA 32kHz ticks) showing the range of ticks vs how accurate the estimation vs noise will be (in this graph under 100 ticks the line gets very nice). The speed was not known, but the duty cycle was (based on 10000 us PWM. The reason was we didnt have speed conversion yet)

Python graph ISR period ticks versus speed. Original graph Odometer_isrticks_vs_speed_lowrange.pdf

[davidzwa]

Duty cycle to speed calibration Speed_mm_per_second => {30, 40, 50, 60, 70, 80, 90, 100, 110, 120}; ISR_ticks_expected => {62, 46, 37, 31, 26, 23, 20, 18, 17, 15}

Resulting speed duty_cycle LUT for an unloaded battery voltage of 7.76V.

PWM period 9000 us, max width 4500 us.

[davidzwa]

PWM period 7000, max width 4000

Lower PWM period is able to push through lower speeds faster/better and more precisely.

With rounding correction:

Another run: