Testing and Validation

This document defines the testing procedures, validation criteria, and results for the Autonomous Industrial Line-Following Robot. All tests are designed to verify subsystem functionality before full system integration.

Test Environment

Parameter	Specification
Power Source	7.4V LiPo battery (2S) or 9V alkaline battery
Test Surface	White surface with 25mm black electrical tape line
Ambient Light	Indoor, fluorescent lighting (typical lab conditions)
Measurement Tools	Digital multimeter, oscilloscope (if available)
Test Firmware	Arduino IDE with serial monitor for debug output

Test Plan Overview

Test ID	Test Name	Priority	Prerequisites
T-01	Power Supply Verification	High	None
T-02	Arduino Nano Functional Check	High	T-01
T-03	Sensor Array Calibration	High	T-02
T-04	Motor Driver Validation	High	T-02
T-05	Individual Motor Test	High	T-04
T-06	PD Control Tuning	Medium	T-03, T-05
T-07	Straight-Line Tracking	Medium	T-06
T-08	Curve Navigation	Medium	T-07
T-09	Intersection Detection	Low	T-08
T-10	Endurance Testing	Low	T-08

T-01: Power Supply Verification

Objective: Verify that the LM7805 voltage regulator provides a stable 5V output under varying load conditions.

Equipment: Digital multimeter

Procedure:

No-Load Test
- Connect battery to J1 (SSQ-102-03-F-S)
- Measure voltage at Arduino Nano 5V pin (no Nano installed)
- Record: Expected ≈ 5.0V ± 0.1V
Light Load Test
- Install Arduino Nano
- Measure voltage at 5V rail
- Record: Expected ≈ 4.9V–5.1V
Full Load Test
- Install all modules (Nano, motor driver, sensors connected)
- Run firmware with motors active
- Measure voltage at 5V rail during motor operation
- Record: Expected ≈ 4.7V–5.1V (allowing for regulator droop)
Ripple Measurement (Oscilloscope, if available)
- Measure AC component on 5V rail during motor PWM operation
- Record: Expected < 100mV peak-to-peak

Pass Criteria:

Condition	Minimum	Maximum
No-load 5V	4.90V	5.10V
Full-load 5V	4.70V	5.10V
Ripple	—	100mV p-p

T-02: Arduino Nano Functional Check

Objective: Verify Arduino Nano is operational and can execute basic I/O operations.

Procedure:

Upload Test Sketch

void setup() {
  Serial.begin(9600);
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  Serial.println("Hello from Nano");
  delay(1000);
  digitalWrite(LED_BUILTIN, LOW);
  delay(1000);
}

Verify
- LED on Nano blinks at 1Hz
- Serial monitor displays "Hello from Nano" every second
- No communication errors
ADC Verification
- Upload analog read sketch
- Read A0–A4 with no sensor connected
- Record: Expected ≈ 0–10 mV (floating, should read low)

T-03: Sensor Array Calibration

Objective: Determine sensor threshold values for reliable line detection and calibrate weighted position calculation.

Equipment: Test track with black line on white surface

Procedure:

Individual Sensor Test
- Upload sensor read sketch that outputs all 5 analog values via serial
- Place sensor array over white surface (no line)
- Record readings for each sensor (S1–S5)
- Place sensor array over black line (centered)
- Record readings for each sensor
Expected Results (approximate):

Surface Sensor Reading (ADC)

White surface 600–900

Black line 100–300
Threshold Determination
- Calculate midpoint between white and black readings
- Threshold = (White_Reading + Black_Reading) / 2
- Example: If white = 800, black = 200, threshold = 500
Position Calibration
- Place line under each sensor position
- Verify weighted position calculation outputs expected values
- Position values should range from 1.0 (far left) to 5.0 (far right)
Noise Assessment
- Record 100 consecutive readings with line centered under S3
- Calculate standard deviation
- Acceptable: σ < 30 ADC counts

Surface	Sensor Reading (ADC)
White surface	600–900
Black line	100–300

Calibration Data Template:

Sensor	White Surface	Black Line	Threshold
S1 (A0)	___ mV	___ mV	___ mV
S2 (A1)	___ mV	___ mV	___ mV
S3 (A2)	___ mV	___ mV	___ mV
S4 (A3)	___ mV	___ mV	___ mV
S5 (A4)	___ mV	___ mV	___ mV

T-04: Motor Driver Validation

Objective: Verify TB6612FNG motor driver responds correctly to control signals.

Procedure:

Logic Supply Test
- Measure voltage at TB6612FNG VCC pin
- Record: Expected ≈ 5.0V
Motor Supply Test
- Measure voltage at TB6612FNG VM pin
- Record: Expected ≈ Battery voltage (7.4V–9V)
Direction Control Test
- Manually set AIN1=HIGH, AIN2=LOW via Arduino
- Verify left motor spins forward
- Set AIN1=LOW, AIN2=HIGH
- Verify left motor spins reverse
- Repeat for BIN1/BIN2 (right motor)
PWM Speed Control Test
- Set motor to forward direction
- Apply PWM duty cycles: 25%, 50%, 75%, 100%
- Verify proportional speed response
- Listen for smooth operation (no stuttering)
Brake Test
- Set AIN1=HIGH, AIN2=HIGH
- Verify motor stops abruptly (brake mode)
- Set AIN1=LOW, AIN2=LOW
- Verify motor coasts to stop (coast mode)

T-05: Individual Motor Test

Objective: Verify both motors operate correctly when connected through the PCB.

Procedure:

Left Motor Test
- Connect left motor to st1 connector
- Run test firmware: full speed forward for 2 seconds, pause, full speed reverse for 2 seconds
- Verify smooth operation in both directions
- Measure motor current (if possible): Expected ~100–200mA no-load
Right Motor Test
- Repeat procedure for right motor on st2
Differential Test
- Run both motors forward at equal PWM
- Verify robot moves straight (place on flat surface briefly)
- Run left motor only, verify robot pivots left
- Run right motor only, verify robot pivots right

T-06: PD Control Tuning

Objective: Optimize Kp and Kd gain parameters for stable line following.

Initial Parameters:

Kp = 25.0    (proportional gain)
Kd = 10.0    (derivative gain)
Base_Speed = 150  (PWM value, 0–255)

Tuning Procedure:

Proportional Tuning (Kp)
- Set Kd = 0
- Start with Kp = 10
- Place robot on line, observe behavior
- Increase Kp by increments of 5 until robot oscillates around the line
- Record Kp_oscillation
- Set Kp = Kp_oscillation × 0.6
Derivative Tuning (Kd)
- With Kp set, start with Kd = 0
- Increase Kd by increments of 2
- Observe: Kd should reduce oscillation without causing sluggish response
- Stop when oscillation is acceptable but response remains fast
Speed Tuning
- With Kp and Kd set, adjust Base_Speed
- Start low (100) and increase gradually
- Find maximum speed where robot reliably follows the line

Expected Outcome:

Robot follows straight line with minimal oscillation
Robot navigates gentle curves (< 90°) without losing the line
No wheel stall or erratic behavior

T-07: Straight-Line Tracking Test

Objective: Validate robot can autonomously follow a straight line.

Test Track: 2-meter straight black line on white surface

Procedure:

Place robot on track with line centered under sensor array
Start firmware
Observe robot following the line
Record:
- Does robot stay on line for full 2 meters? (Y/N)
- Number of corrections (lateral movements)
- Average deviation from center (visual estimate)

Pass Criteria:

Robot completes 2-meter straight line without leaving the track
Smooth, minimal oscillation
No manual intervention required

T-08: Curve Navigation Test

Objective: Validate robot can navigate curves of varying radii.

Test Track: Track with curves of decreasing radius (large → medium → tight)

Procedure:

Run robot on track with 500mm radius curve
Run robot on track with 200mm radius curve
Run robot on track with 100mm radius curve (if available)
Record success/failure at each radius

Pass Criteria:

Successfully navigates 200mm radius curves
May lose line at 100mm radius (acceptable for basic implementation)

T-09: Intersection Detection Test (Future Enhancement)

Objective: Test ability to detect and respond to track intersections.

Note: This test requires firmware modifications to implement intersection detection logic. Currently a placeholder for future development.

T-10: Endurance Test

Objective: Verify sustained operation over extended period.

Procedure:

Fully charge battery
Start robot on a closed-loop track (if available)
Record runtime until battery depletion or system failure
Monitor for:
- Thermal issues (motor driver, regulator)
- Cumulative drift in line following
- Any intermittent failures

Expected Runtime: 15–30 minutes depending on battery capacity and motor load.

Common Issues and Troubleshooting

Symptom	Probable Cause	Solution
Robot veers strongly left/right	Sensor calibration incorrect	Recalibrate sensor thresholds
Robot oscillates wildly	Kp too high	Reduce Kp gain
Robot responds slowly to curves	Kp too low or Kd too high	Increase Kp or reduce Kd
One motor doesn't spin	Loose connector or dead driver channel	Check st1/st2 connections
Robot runs in circles	Motor wiring reversed	Swap motor terminal connections
5V rail drops below 4.5V	Battery depleted or regulator fault	Replace battery or check regulator
Erratic sensor readings	Electrical noise, loose sensor	Check sensor mounting height, add filtering
Robot stops unexpectedly	Motor stall or brown-out	Check battery voltage, reduce speed

Test Result Documentation

All test results should be recorded in the following format:

Test ID:    T-XX
Date:       YYYY-MM-DD
Tester:     [Name]
Result:     PASS / FAIL / PARTIAL
Notes:      [Observations]
Data:       [Measured values]

Safety Notes

Disconnect battery before making wiring changes
Do not touch motor terminals during operation
Ensure robot has clear space around the test area
Keep fingers away from moving wheels
Monitor component temperatures during initial testing

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Testing and Validation

Test Environment

Test Plan Overview

T-01: Power Supply Verification

T-02: Arduino Nano Functional Check

T-03: Sensor Array Calibration

T-04: Motor Driver Validation

T-05: Individual Motor Test

T-06: PD Control Tuning

T-07: Straight-Line Tracking Test

T-08: Curve Navigation Test

T-09: Intersection Detection Test (Future Enhancement)

T-10: Endurance Test

Common Issues and Troubleshooting

Test Result Documentation

Safety Notes