FMRREHAB: Functional Movement Robotic Rehabilitation platform (a Fit4Med project)

Fmrrehab is a comprehensive rehabilitation robotics platform built on ROS 2 with advanced motion control, force-torque sensing, and safety-critical PLC integration. The system coordinates a 3-DOF rehabilitation arm through a real-time control architecture with emergency stop chains and sensor-based impedance control.

System Architecture

Dual Controller Manager Setup The system uses two separate controller-manager instances for safety isolation:

Safety control stack (always running)

The safety PLC module installed in the FMRREHAB platform is managed by the following ros2 nodes at a 500 Hz control loop: PLC Controller Manager
└─ PLC Controller - Reads/writes 8 GPIO command outputs
- Reads 8 GPIO state inputs
- Publishes PlcStates for subscribers

Motion control stack (started by the user)

The following controllers are automathically loaded and will run at 250 Hz:

• Joint Trajectory Controller
• Forward Velocity Controller
• Impedance Controller
• Force/Torque Sensor Broadcaster

Rehabilitation GUI

(PyQt5 Interface with SSH Remote Access)
High-Level user interface with SSH connection for remote launching and UDP client for status monitoring

Repository Structure

Core Packages

1. tecnobody_workbench - Central Configuration Package

Master configuration package containing all URDF definitions, controller YAML configs, and launch files.

2. plc_manager - Safety State Machine

ROS 2 node managing system lifecycle through PLC state transitions.

3. plc_controller - ROS 2 Control Plugin

C++ controller plugin implementing GPIO bridge between ROS 2 and Safety PLC.

4. tecnobody_workbench_utils - Core Control Nodes

This package provides the primary motion control and sensor management modules needed by the motion control stack.

5. rehab_gui - User Interface

Multi-Platform user interface developed with QT managing robot high-level control by the user and rehabilitation exercise configuration.

Supporting Packages

6. bash_scripts - ROS 2 Environment Management

launch_ros2_env.sh
Launches ros2 control framework and default controllers, managing two cases:

• first launch: homing process performed
• launch after an emergency stop by the user: no homing needed

kill_ros_apps.sh

• Gracefully unspawn all active controllers
• Unload inactive controllers
• Coordinate with PLC manager for clean shutdown

7. ps_scripts - PowerShell Remote Execution (Windows GUI)

• fmrr_gui.ps1 - launch GUI
• fmrr_bringup.ps1 - SSH into Linux, start ROS2 stack via PLC launcher
• fmrr_cleanup.ps1 - SSH into Linux, gracefully shut down all nodes
• fmrr_scp.ps1 - Transfer files remotely between Windows & Linux

8. tecnobody_msgs - Custom Message and Services Types

• PlcController.msg - Command messages to PLC
• PlcStates.msg - State feedback from PLC
• SetExercise.srv - Exercise execution request
• SetTrajectory.srv - Tajectory execution request

Troubleshooting

Common Issues

1. EtherCAT PLC Not Operational Check EtherCAT slaves: ethercat slaves # Expected: "FLX0-GETC100 OP" ethercat master # If not OP, check ethercat master

2. Homing Timeout

• Check motor connection (ESTOP signal must be active)
• Verify safe movement zone (no mechanical obstructions)
• Increase timeout in boot_hw.py if needed

3. GUI Not Receiving Status

• Verify UDP port 5005 is open
• Check network connectivity (SSH must work)
• Verify GUI IP in plc_manager launch: gui_ip:=<windows_ip>

4. Trajectory Execution Hangs

• Check joint_trajectory_controller state: ros2 control list_controllers
• Verify all joints in "active" state
• Check for controller timeouts in /tmp/launch logs

License

This project is licensed under the Apache-2.0 License. See LICENSE file for details.

Contact

For questions about this rehabilitation platform, contact Nicola Pedrocchi and Adriano Scibilia