SensorModule

Overview

The SensorModule class provides a unified interface to all hardware sensors on the VEX IQ robotic arm. It manages the Brain, inertial sensor, distance sensors, bumper, and touch LED, offering convenient methods for reading sensor data and controlling outputs. Source: ~/workspace/source/arm_controller/src/main.py:76

Constructor

`init()`

Initializes all sensor hardware components with their port configurations.

sensors = SensorModule()

Initialized Sensors:

brain

Brain

VEX Brain controller with screen and button interface

inertial

Inertial

3-axis gyroscope for angle and rotation measurements. Requires calibration before use.

gripper_distance

Distance

Distance sensor on gripper (Port 7). Measures object distance in gripper proximity.Port: Ports.PORT7

touchled

Touchled

RGB LED with touch sensitivity (Port 10). Used for status indication.Port: Ports.PORT10

base_distance

Distance

Distance sensor on rotating base (Port 11). Primary sensor for environmental scanning.Port: Ports.PORT11

bumper

Bumper

Mechanical bumper switch (Port 12). Safety sensor for shoulder collision detection.Port: Ports.PORT12

Source: main.py:77

Brain Screen Methods

`clear_screen()`

Clears all content from the VEX Brain display.

sensors.clear_screen()

Source: main.py:86

`print_screen(text: str, coordinate_x: int, coordinate_y: int)`

Displays text at specified screen coordinates.

sensors.print_screen("Temperature: 25°C", 10, 50)

text

str

required

Text string to display on screen

coordinate_x

int

required

Horizontal pixel position (0 = left edge)

coordinate_y

int

required

Vertical pixel position (0 = top edge)

Screen Resolution:

VEX IQ Brain: 228×128 pixels
Origin (0,0) at top-left corner

Source: main.py:89

Inertial Sensor Methods

`calibrate_intertial_sensor()`

Calibrates the inertial sensor. Robot must remain stationary during calibration.

sensors.calibrate_intertial_sensor()

The robot must be completely still during calibration. Movement will cause inaccurate readings.

Duration: Typically 2-3 seconds When to Calibrate:

On robot startup
After significant temperature changes
If angle readings drift
After physical impacts

Source: main.py:93

`get_angle()`

Returns the current heading angle from the inertial sensor.

angle = sensors.get_angle()
print(f"Current heading: {angle}°")

return

float

Current heading angle in degrees (0-360°)

0°: Initial calibration position
Increases with clockwise rotation
Wraps around at 360°

Use Cases:

Tracking rotation during environmental scans
Calculating object angular positions
Returning to specific orientations

Source: main.py:96

Distance Sensor Methods

`get_base_distance()`

Reads distance from the base-mounted distance sensor.

distance = sensors.get_base_distance()
if 50 <= distance <= 300:
    print(f"Object detected at {distance}mm")

return

float

Distance to nearest object in millimeters (mm)

Range: 20-2000mm (typical)
Accuracy: ±3mm
Returns large value if no object detected

Detection Range:

Minimum: ~20mm
Optimal: 50-300mm (used for object detection)
Maximum: ~2000mm

Source: main.py:100

`get_base_object_size()`

Returns the raw size measurement from base distance sensor.

size = sensors.get_base_object_size()
print(f"Object size metric: {size}")

return

int

Raw size value (0-400 typical)

Higher values indicate larger objects
Unitless metric (not physical dimensions)
Used for relative size comparison

Interpretation:

0: No object detected
1-100: Small object (bottle cap, pen)
100-200: Medium object (cup, bottle)
200+: Large object (box, container)

Source: main.py:103

`get_gripper_distance()`

Reads distance from the gripper-mounted distance sensor.

gripper_dist = sensors.get_gripper_distance()
if gripper_dist < 30:
    print("Object in gripper range")

return

float

Distance in millimeters from gripper sensor to nearest object

Range: 20-200mm (shorter range than base sensor)
Used to verify object grip

Use Cases:

Confirming object capture
Fine-tuning gripper approach
Verifying gripper is empty

Source: main.py:106

Bumper Methods

`is_bumper_pressed()`

Checks if the mechanical bumper switch is pressed.

if sensors.is_bumper_pressed():
    print("WARNING: Bumper collision detected!")
    # Emergency stop

return

bool

True: Bumper is currently pressed (collision detected)
False: Bumper is not pressed (normal state)

Bumper activation indicates physical contact. Immediate motor stop is recommended to prevent damage.

Typical Usage:

Safety checks during shoulder movement
Emergency stop trigger
Collision avoidance validation

Source: main.py:110

Touch LED Methods

`set_color(color: tuple)`

Sets the RGB color of the touch LED for status indication.

# Red for error
sensors.set_color((255, 0, 0))

# Green for ready
sensors.set_color((0, 255, 0))

# Blue for scanning
sensors.set_color((0, 0, 255))

color

tuple[int, int, int]

required

RGB color tuple (red, green, blue)

Each component: 0-255
(0, 0, 0): Off
(255, 255, 255): White

Standard Colors (from LEDColors class):

ERROR = (255, 0, 0)             # Red: Error/Stop
WARNING = (255, 150, 0)         # Orange: Warning
READY = (0, 255, 0)             # Green: Ready
RUNNING = (0, 0, 255)           # Blue: Process Running
OBJECT_DETECTED = (0, 255, 155) # Cyan: Object Detected

Source: main.py:114

Hardware Verification

`check_sensors()`

Verifies that all critical sensors are properly installed and responsive.

if sensors.check_sensors():
    print("All sensors operational")
else:
    print("ERROR: Sensor installation issue")

return

bool

Returns True if all sensors installed, False if any sensor missing or unresponsive

Checked Sensors:

Base distance sensor (Port 11)
Gripper distance sensor (Port 7)
Bumper switch (Port 12)

Not Checked:

Brain (always available)
Inertial sensor (always available)
Touch LED (always available)

Source: main.py:119

Port Configuration Summary

Sensor	Port	Type	Purpose
Gripper Distance	PORT7	Distance	Gripper proximity detection
Touch LED	PORT10	Touchled	Status indication
Base Distance	PORT11	Distance	Environmental scanning
Bumper	PORT12	Bumper	Collision safety
Inertial	Internal	Inertial	Angle measurement
Brain	Internal	Brain	Display and control

Sensor Data Flow

The sensor data flows through the system as follows:

SensorModule
    ↓
PerceptionModule (processes sensor data)
    ↓
MappingModule (builds spatial map)
    ↓
RoboticServices (coordinates actions)

Example Scan Cycle:

# 1. Read sensors
angle = sensors.get_angle()              # 45.0°
distance = sensors.get_base_distance()   # 150mm
size = sensors.get_base_object_size()    # 85

# 2. Update status LED
if 50 <= distance <= 300:
    sensors.set_color((0, 255, 155))  # Cyan: object detected
else:
    sensors.set_color((0, 0, 255))    # Blue: scanning

# 3. Display on screen
sensors.print_screen(f"Angle: {angle:.1f}°", 10, 20)
sensors.print_screen(f"Dist: {distance}mm", 10, 40)

Usage Examples

Complete Sensor Initialization

from vex import *
import time

# Initialize sensor module
sensors = SensorModule()

# Clear screen
sensors.clear_screen()

# Verify hardware
if not sensors.check_sensors():
    sensors.set_color((255, 0, 0))  # Red error
    sensors.print_screen("SENSOR ERROR", 10, 50)
    raise Exception("Sensors not installed")

# Calibrate inertial sensor
sensors.print_screen("Calibrating...", 10, 10)
sensors.calibrate_intertial_sensor()
time.sleep(2)

# Ready state
sensors.set_color((0, 255, 0))  # Green
sensors.print_screen("READY", 10, 10)

Object Detection Loop

while True:
    # Read sensors
    distance = sensors.get_base_distance()
    size = sensors.get_base_object_size()
    angle = sensors.get_angle()
    
    # Check for objects
    if 50 <= distance <= 300:
        sensors.set_color((0, 255, 155))  # Cyan
        sensors.print_screen(f"OBJECT: {size}", 10, 30)
        sensors.print_screen(f"Dist: {distance}mm", 10, 50)
        sensors.print_screen(f"Angle: {angle:.1f}°", 10, 70)
    else:
        sensors.set_color((0, 0, 255))  # Blue
        sensors.print_screen("Scanning...", 10, 30)
    
    time.sleep(0.05)  # 20Hz update rate

Safety Monitoring

def monitor_safety(sensors, control_module):
    """Continuous safety monitoring"""
    if sensors.is_bumper_pressed():
        # Emergency stop
        control_module.general_stop()
        sensors.set_color((255, 0, 0))  # Red
        sensors.print_screen("COLLISION!", 10, 60)
        return False
    return True

RoboticServices - Main orchestrator that uses sensor data
ControlModule - Motor control coordinated with sensors
CommunicationManager - Sends sensor data to Raspberry Pi

Core Classes

Segmentation

Drawing Components

Robotics

Overview

Constructor

`init()`

Brain Screen Methods

`clear_screen()`

`print_screen(text: str, coordinate_x: int, coordinate_y: int)`

Inertial Sensor Methods

`calibrate_intertial_sensor()`

`get_angle()`

Distance Sensor Methods

`get_base_distance()`

`get_base_object_size()`

`get_gripper_distance()`

Bumper Methods

`is_bumper_pressed()`

Touch LED Methods

`set_color(color: tuple)`

Hardware Verification

`check_sensors()`

Port Configuration Summary

Sensor Data Flow

Usage Examples

Complete Sensor Initialization

Object Detection Loop

Safety Monitoring

Build docs developers (and LLMs) love

Core Classes

Segmentation

Drawing Components

Robotics

​Overview

​Constructor

​__init__()

​Brain Screen Methods

​clear_screen()

​print_screen(text: str, coordinate_x: int, coordinate_y: int)

​Inertial Sensor Methods

​calibrate_intertial_sensor()

​get_angle()

​Distance Sensor Methods

​get_base_distance()

​get_base_object_size()

​get_gripper_distance()

​Bumper Methods

​is_bumper_pressed()

​Touch LED Methods

​set_color(color: tuple)

​Hardware Verification

​check_sensors()

​Port Configuration Summary

​Sensor Data Flow

​Usage Examples

​Complete Sensor Initialization

​Object Detection Loop

​Safety Monitoring

​Related Classes

Build docs developers (and LLMs) love

Overview

Constructor

`init()`

Brain Screen Methods

`clear_screen()`

`print_screen(text: str, coordinate_x: int, coordinate_y: int)`

Inertial Sensor Methods

`calibrate_intertial_sensor()`

`get_angle()`

Distance Sensor Methods

`get_base_distance()`

`get_base_object_size()`

`get_gripper_distance()`

Bumper Methods

`is_bumper_pressed()`

Touch LED Methods

`set_color(color: tuple)`

Hardware Verification

`check_sensors()`

Port Configuration Summary

Sensor Data Flow

Usage Examples

Complete Sensor Initialization

Object Detection Loop

Safety Monitoring

Related Classes