Long-horizon Task Completion with Robotic Arms by Human Instructions

This repository contains the code and documentation for the ECE 445 Senior Design project, "Long-horizon Task Completion with Robotic Arms by Human Instructions." The project focuses on developing a robotic system to assist individuals with limited mobility by understanding high-level human instructions and autonomously performing complex, multi-step tasks.

Abstract

This project developed a robotic system to assist individuals with limited mobility by understanding human instructions and autonomously performing long-horizon tasks like table cleaning. The system integrates Perception (Vision Language Models like Qwen-VL, Grounded SAM), Planning (VLMs for task/motion planning), Control (Raspberry Pi 5, ROS 2), and Action (custom force-feedback gripper) modules. Key achievements include successful module integration, advanced AI implementation (90% object identification accuracy), and custom hardware development (force-sensing PCB, lead screw gripper). This work demonstrates a viable approach for creating intelligent robotic assistants capable of complex instruction interpretation and real-world interaction, advancing autonomous and helpful robotics.

Key Features

• Advanced AI Integration: Utilizes state-of-the-art Vision Language Models (Qwen-VL, Grounded SAM) for robust scene understanding, object identification, and task planning.
• High-Level Instruction Following: Capable of interpreting general human commands (e.g., "Put everything into the box") and decomposing them into a sequence of executable actions.
• Custom Force-Feedback Gripper: A custom-designed and 3D-printed gripper with a lead screw mechanism and an integrated FSR402 force sensor allows for precise and safe object manipulation.
• Modular ROS 2 Architecture: The system is built on ROS 2, running on a Raspberry Pi 5, ensuring real-time, reliable communication between all hardware and software components.
• End-to-End Task Execution: Demonstrates a complete pipeline from visual perception and planning to physical action, enabling the robot to perform long-horizon tasks in a dynamic environment.

System Architecture

The system is composed of four primary modules:

1. Perception Module: Uses a 4K camera and Vision Language Models to identify and locate objects in the robot's workspace. It generates a scene description and provides the 3D coordinates of objects.
2. Planning Module: Takes the user's instruction and the scene description to generate a feasible, multi-step plan. It uses a VLM to reason about the physical constraints and task sequence.
3. Control Module: The central hub running on a Raspberry Pi 5. It uses ROS 2 to manage communication and synchronize actions between the perception and planning servers, the UR3e arm controller, and the gripper's motor and sensor.
4. Action Module: Consists of the UR3e robotic arm and the custom-built gripper. It executes the motion commands and uses force feedback to confirm successful grasps.

Hardware and Software

Hardware

• Robotic Arm: Universal Robots UR3e
• Central Controller: Raspberry Pi 5
• Visual Sensor: 4K Raspberry Pi Camera
• Gripper: Custom 3D-printed design with a stepper motor and lead screw.
• Force Sensor: FSR402 with a custom PCB for signal processing and amplification.

Software

• OS: Ubuntu 24.04 LTS
• Robotics Framework: ROS 2
• AI Models: Qwen-VL, Grounded SAM
• API Framework: FastAPI with Uvicorn for serving the AI models.
• Key Python Libraries: rclpy, gpiozero, serial, opencv-python.

Setup and Installation

1. Hardware Setup:

   • Connect the UR3e arm, Raspberry Pi 5, and camera via Ethernet and CSI, respectively.
   • Attach the custom gripper to the UR3e's end-effector flange.
   • Connect the gripper's stepper motor controller and FSR sensor PCB to the Raspberry Pi 5's UART and GPIO pins.

2. Software Environment:

   • Install Ubuntu 24.04 and ROS 2 on the Raspberry Pi 5.
   • Set up a separate server (or use a powerful local machine) to host the Perception (Grounded SAM) and Planning (Qwen-VL) models, exposing them via a FastAPI endpoint.
   • Clone this repository to your Raspberry Pi.

3. Install Dependencies:

   • Install the required system packages and Python libraries.

   pip install -r requirements.txt

4. Build and Source ROS 2 Packages:

   • Navigate to your ROS 2 workspace.
   • Build the custom packages (fsr_sensor, gripper_control):

   colcon build

   • Source the workspace to make the packages available:

   source install/setup.bash

Usage

1. Launch the System:
   • Start the core control nodes for the gripper and force sensor using the provided launch file:

   ros2 launch gripper_control combined_launch.py

2. Run the Main Application:
   • Execute the main script that orchestrates the perception, planning, and action loop.
3. Provide Instructions:
   • Give a high-level command to the system through the designated user interface. The robot will then capture the scene, generate a plan for approval, and execute the task.

Future Work

• Enhance robustness in cluttered and unfamiliar environments.
• Improve handling of object occlusions and reflective surfaces.
• Scale the system to handle more complex and nuanced human instructions.
• Refine human-robot interaction to better manage ambiguity and implicit intent.