Leptrino Force Torque Sensor

This code is referred and used for Leptrino 6-DoF Force Torque Sensor.

Some features are referred to hiveground.

A ROS 2 repository that interfaces with 6-DoF Leptrino Force Sensor. The offset of force sensor has been calculated to get actual force measurements. Enhanced with automatic recalibration capabilities for improved long-term accuracy.

Features

• Real-time force/torque data - 6-DoF measurements at 1kHz
• Automatic calibration - Removes sensor drift and offset errors
• Multiple calibration methods - Service calls, topic triggers, or time-based
• Calibration monitoring - Real-time status feedback
• Thread-safe operation - Safe concurrent access to calibration functions
• Configurable parameters - Flexible setup for different applications

1. Download and Build Package

Download the source repository

cd /path/to/ros2-workspace/src
git clone https://github.com/labiybafakh/leptrino_force_torque_sensor

Compile the package

cd /path/to/ros2-workspace/
colcon build --symlink-install --packages-select leptrino_force_torque_sensor --cmake-args -DCMAKE_BUILD_TYPE=Release

Source the workspace

source install/local_setup.bash

2. Basic Launch

Set serial port permissions

sudo chmod 666 /dev/ttyACM0

Launch the sensor node

ros2 launch leptrino_force_torque_sensor leptrino.launch.py 

Launch with custom parameters

# Launch with different serial port
ros2 launch leptrino_force_torque_sensor leptrino.launch.py com_port:=/dev/ttyUSB0

# Launch with auto-recalibration enabled
ros2 launch leptrino_force_torque_sensor leptrino.launch.py \
  auto_recalibration_enabled:=true \
  auto_recalibration_interval_minutes:=15.0

# Launch with custom calibration sample count
ros2 launch leptrino_force_torque_sensor leptrino.launch.py \
  calibration_samples:=200

3. Sensor Calibration

Why Calibration is Important

Force-torque sensors experience drift over time due to:

• Temperature changes - Affects strain gauge readings
• Mechanical stress - Mounting forces and vibrations
• Electronic drift - Amplifier offset changes
• Gravitational effects - Sensor orientation dependency
• Component aging - Long-term material changes

Calibration removes these systematic errors by measuring the sensor's zero-point when no external forces are applied.

Calibration Methods

Method 1: Manual Calibration via Service (Recommended)

When to use: For on-demand, precise calibration.

# Trigger calibration
ros2 service call /leptrino/recalibrate std_srvs/srv/Trigger

# Expected response:
# success: True
# message: "Recalibration completed successfully"

Method 2: Topic-Based Calibration

When to use: For integration with external systems or automated workflows.

# Trigger calibration via topic
ros2 topic pub /leptrino/recalibrate_trigger std_msgs/msg/Empty "{}" --once

Method 3: Automatic Calibration

When to use: For continuous operation without manual intervention.

Configure in config/params.yaml:

leptrino_sensor:
  ros__parameters:
    auto_recalibration_enabled: true
    auto_recalibration_interval_minutes: 30.0  # Every 30 minutes
    calibration_samples: 100

Or via launch parameters:

ros2 launch leptrino_force_torque_sensor leptrino.launch.py \
  auto_recalibration_enabled:=true \
  auto_recalibration_interval_minutes:=20.0

Calibration Best Practices

Pre-Calibration Setup

1. Ensure no external forces - Remove all loads from the sensor
2. Stable mounting - Minimize vibrations and movement
3. Temperature stability - Wait for thermal equilibrium (~5 minutes)
4. Proper orientation - Sensor should be in operational position

Calibration Steps

# 1. Launch the sensor
ros2 launch leptrino_force_torque_sensor leptrino.launch.py

# 2. Wait for sensor initialization (check logs for "Data acquisition is started")

# 3. Remove all external forces from the sensor

# 4. Trigger calibration
ros2 service call /leptrino/recalibrate std_srvs/srv/Trigger

# 5. Wait for completion (typically 100ms for 100 samples)

# 6. Verify calibration success in logs

Monitoring Calibration Status

# Monitor calibration status in real-time
ros2 topic echo /leptrino/calibration_status

# While calibrating: data: true
# When complete: data: false

Calibration Timing Guidelines

Application	Frequency	Trigger
Research/Lab	Before each experiment	Manual service call
Industrial	Every 15-30 minutes	Automatic timer
Robotics	Before precision tasks	Programmatic service call
Continuous	Temperature change >5°C	Manual or automatic

4. Configuration Parameters

Available Parameters

Parameter	Type	Default	Description
com_port	string	/dev/ttyACM0	Serial port device
auto_recalibration_enabled	bool	false	Enable automatic recalibration
auto_recalibration_interval_minutes	double	30.0	Minutes between auto-calibrations
calibration_samples	int	100	Number of samples for calibration

Parameter Configuration

Via config file (config/params.yaml):

leptrino_sensor:
  ros__parameters:
    com_port: "/dev/ttyACM0"
    auto_recalibration_enabled: true
    auto_recalibration_interval_minutes: 15.0
    calibration_samples: 200

Via launch arguments:

ros2 launch leptrino_force_torque_sensor leptrino.launch.py \
  com_port:=/dev/ttyACM0 \
  auto_recalibration_enabled:=true \
  auto_recalibration_interval_minutes:=10.0 \
  calibration_samples:=150

5. Topics and Services

Published Topics

Topic	Message Type	Description
/leptrino	geometry_msgs/WrenchStamped	Force/torque measurements
/leptrino/calibration_status	std_msgs/Bool	Calibration status (true = calibrating)

Subscribed Topics

Topic	Message Type	Description
/leptrino/recalibrate_trigger	std_msgs/Empty	Trigger calibration via topic

Services

Service	Service Type	Description
/leptrino/recalibrate	std_srvs/Trigger	Manual calibration trigger

Example Usage

# Monitor force/torque data
ros2 topic echo /leptrino

# Monitor calibration status
ros2 topic echo /leptrino/calibration_status

# Trigger calibration via service
ros2 service call /leptrino/recalibrate std_srvs/srv/Trigger

# Trigger calibration via topic
ros2 topic pub /leptrino/recalibrate_trigger std_msgs/msg/Empty "{}" --once

# List all leptrino topics
ros2 topic list | grep leptrino

# List all leptrino services
ros2 service list | grep leptrino