Flying Calligrapher: Contact-Aware Motion and Force Planning and Control for Aerial Manipulation

2024-07-08

IEEE Robotics and Automation Letters

AI Summary

This work addresses the challenge of simultaneously tracking time-varying normal contact forces and desired trajectories in dynamic aerial contact scenarios—particularly for fine, force-position tightly coupled tasks such as aerial calligraphy. We propose the first integrated framework for joint tracking of time-varying contact forces and tangential motion trajectories. Our method combines contact-aware trajectory planning with a hybrid force–position control strategy; we further design a custom soft-sponge stylus tip enabling force-modulated stroke-width control, and integrate a touch-based interface for real-time handwritten input. Experimental evaluation demonstrates successful multi-character aerial writing, achieving an Intersection-over-Union (IoU) of 0.59, an end-effector position tracking RMSE of 2.9 cm, and a normal force tracking RMSE of 0.7 N. The framework significantly improves force–position coordination accuracy under dynamic curved-surface contact and enhances human–robot interaction flexibility.

Technology Category

• Intelligent Robots: Manipulation
• Humans and AI: Interaction Techniques and Devices
• Planning, Routing, and Scheduling: Activity and Plan Recognition

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications

Abstract

Aerial manipulation has gained interest in completing high-altitude tasks that are challenging for human workers, such as contact inspection and defect detection, etc. Previous research has focused on maintaining static contact points or forces. This letter addresses a more general and dynamic task: simultaneously tracking time-varying contact force in the surface normal direction and motion trajectories on tangential surfaces. We propose a pipeline that includes a contact-aware trajectory planner to generate dynamically feasible trajectories, and a hybrid motion-force controller to track such trajectories. We demonstrate the approach in an aerial calligraphy task using a novel sponge pen design as the end-effector, whose stroke width is positively related to the contact force. Additionally, we develop a touchscreen interface for flexible user input. Experiments show our method can effectively draw diverse letters, achieving an IoU of 0.59 and an end-effector position (force) tracking RMSE of 2.9 cm (0.7N).

Problem

• Tracking time-varying contact force and motion trajectories simultaneously
• Developing a contact-aware trajectory planner and hybrid controller
• Enabling aerial manipulation for dynamic tasks like calligraphy

Innovation

• Contact-aware trajectory planner for dynamic tasks
• Hybrid motion-force controller for precise tracking
• Novel sponge pen design for force-sensitive strokes