Multiple sensor fusion in Arduino - Step-by-Step Execution

Concept Flow - Multiple sensor fusion

Read Sensor 1

↓

Read Sensor 2

↓

Read Sensor 3

↓

Combine Sensor Data

↓

Apply Fusion Algorithm

↓

Output Fused Result

↓

Repeat Loop

The program reads multiple sensors one by one, combines their data, applies a fusion algorithm, and outputs the final fused result repeatedly.

Execution Sample

Arduino

int sensor1 = analogRead(A0);
int sensor2 = analogRead(A1);
int sensor3 = analogRead(A2);
int fused = (sensor1 + sensor2 + sensor3) / 3;
Serial.println(fused);

Reads three analog sensors, averages their values, and prints the fused result.

Execution Table

Step	sensor1	sensor2	sensor3	fused	Action	Output
1	523				Read sensor1 from A0
2	523	487			Read sensor2 from A1
3	523	487	510		Read sensor3 from A2
4	523	487	510	506	Calculate average fused = (523+487+510)/3
5	523	487	510	506	Print fused value	506
6					Loop repeats for next readings

💡 Loop runs continuously; no exit unless device is powered off.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
sensor1	0	523	523	523	523	523
sensor2	0	0	487	487	487	487
sensor3	0	0	0	510	510	510
fused	0	0	0	0	506	506

Key Moments - 3 Insights

Why do we read each sensor separately before combining?

Each sensor value is read step-by-step (see execution_table rows 1-3) to get accurate individual readings before fusion.

How is the fused value calculated?

The fused value is the average of all sensor readings, calculated in step 4 by adding sensor1, sensor2, and sensor3, then dividing by 3.

Why does the loop repeat endlessly?

Arduino loops run continuously to keep updating sensor readings and fused output, as shown in step 6.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of sensor2 after Step 2?

A 510

B 523

C 487

D 0

💡 Hint

Check the 'sensor2' column in execution_table row for Step 2.

At which step is the fused value calculated?

A Step 4

B Step 2

C Step 5

D Step 3

💡 Hint

Look for the step where 'fused' variable gets a value in execution_table.

If sensor3 reads 600 instead of 510, what would be the new fused value at Step 4?

A 506

B 536

C 523

D 540

💡 Hint

Calculate average of sensor1=523, sensor2=487, sensor3=600 as shown in variable_tracker.

Concept Snapshot

Multiple sensor fusion in Arduino:
- Read each sensor separately using analogRead(pin)
- Combine readings (e.g., average) to fuse data
- Use fused value for better accuracy
- Repeat in loop for continuous updates
- Output fused result via Serial or other means

Full Transcript

This example shows how an Arduino program reads three sensors one by one, stores their values, then calculates the average as a simple fusion method. The fused value is printed to the serial monitor. The loop repeats to keep updating the fused data continuously. Variables sensor1, sensor2, and sensor3 hold individual readings, and fused holds the combined average. This step-by-step process helps beginners understand how multiple sensor data can be combined for better results.

Practice

1. What is the main purpose of multiple sensor fusion in Arduino projects?

easy

A. To make sensors work independently without Arduino

B. To combine data from different sensors for better accuracy

C. To reduce the power consumption of sensors

D. To increase the number of sensors connected to Arduino

Solution

1. Step 1: Understand sensor fusion concept

   Multiple sensor fusion means combining data from different sensors to get more reliable results.

2. Step 2: Identify the main goal

   The goal is to improve accuracy by using data from multiple sources.

3. Final Answer:

   To combine data from different sensors for better accuracy -> Option B

4. Quick Check:

   Sensor fusion = combine data for accuracy [OK]

Hint: Sensor fusion means combining sensor data for accuracy [OK]

Common Mistakes:

• Thinking sensor fusion just adds more sensors
• Confusing power saving with fusion
• Assuming sensors work independently

2. Which Arduino function is commonly used to read analog sensor values for fusion?

easy

A. analogRead()

B. digitalRead()

C. sensorRead()

D. readAnalog()

Solution

1. Step 1: Recall Arduino sensor reading functions

   Arduino uses digitalRead() for digital sensors and analogRead() for analog sensors.

2. Step 2: Identify correct function for analog sensors

   analogRead() reads analog sensor values needed for fusion.

3. Final Answer:

   analogRead() -> Option A

4. Quick Check:

   Analog sensor read = analogRead() [OK]

Hint: Use analogRead() for analog sensors in Arduino [OK]

Common Mistakes:

• Using digitalRead() for analog sensors
• Choosing non-existent functions like sensorRead()
• Confusing function names

3. What will be the output of this Arduino code snippet for sensor fusion?

int sensor1 = 400;
int sensor2 = 600;
int fusedValue = (sensor1 + sensor2) / 2;
Serial.println(fusedValue);

medium

A. 500

B. 400

C. 1000

D. 600

Solution

1. Step 1: Calculate sum of sensor values

   sensor1 + sensor2 = 400 + 600 = 1000

2. Step 2: Calculate average for fusion

   Average = 1000 / 2 = 500

3. Final Answer:

   500 -> Option A

4. Quick Check:

   (400+600)/2 = 500 [OK]

Hint: Average sensor values by adding and dividing by count [OK]

Common Mistakes:

• Adding but forgetting to divide
• Dividing by wrong number
• Printing wrong variable

4. Identify the error in this Arduino code for fusing two sensor readings:

int sensor1 = analogRead(A0);
int sensor2 = analogRead(A1);
int fusedValue = sensor1 + sensor2 / 2;
Serial.println(fusedValue);

medium

A. analogRead() cannot be used on pins A0 and A1

B. Serial.println() cannot print integers

C. fusedValue should be a float, not int

D. The division operator has higher precedence, so sensor2 is divided by 2 before adding sensor1

Solution

1. Step 1: Analyze operator precedence in expression

   Division (/) has higher precedence than addition (+), so sensor2 / 2 happens first.

2. Step 2: Understand the effect on fusedValue

   Expression equals sensor1 + (sensor2 / 2), not (sensor1 + sensor2) / 2 as intended.

3. Final Answer:

   The division operator has higher precedence, so sensor2 is divided by 2 before adding sensor1 -> Option D

4. Quick Check:

   Operator precedence causes wrong fusion calculation [OK]

Hint: Use parentheses to control math order in fusion calculations [OK]

Common Mistakes:

• Ignoring operator precedence
• Thinking analogRead() is invalid on A0/A1
• Believing Serial.println() can't print ints

5. You have three sensors giving values: 300, 450, and 500. To fuse these readings and reduce noise, which Arduino code correctly calculates the average value?

hard

A. int fused = (300 + 450 + 500) * 3;

B. int fused = 300 + 450 + 500 / 3;

C. int fused = (300 + 450 + 500) / 3;

D. int fused = (300 + 450 + 500) / 2;

Solution

1. Step 1: Understand correct averaging formula

   Average = sum of values divided by number of values, so (300+450+500)/3.

2. Step 2: Check each option's calculation

   int fused = (300 + 450 + 500) / 3; correctly sums all and divides by 3. int fused = 300 + 450 + 500 / 3; divides only 500 by 3, wrong order. int fused = (300 + 450 + 500) * 3; multiplies sum by 3, wrong. int fused = (300 + 450 + 500) / 2; divides by 2, wrong count.

3. Final Answer:

   int fused = (300 + 450 + 500) / 3; -> Option C

4. Quick Check:

   Average = sum/3 = correct fusion [OK]

Hint: Sum all sensor values, then divide by count with parentheses [OK]

Common Mistakes:

• Missing parentheses causing wrong math order
• Dividing only last value
• Multiplying instead of dividing