[Paper Review] Casting Robotic End-effectors To Reach Faraway Moving Objects

Adriano Fagiolini, Hitoshi Arisumi+1 more|arXiv (Cornell University)|Jan 12, 2011

Robotic Path Planning Algorithms3 citations

TL;DR

This paper proposes a 3D casting manipulation system that enables robotic end-effectors to catch distant, moving objects using a tethered throw and real-time visual feedback. By integrating simplified dynamic models and a vision-based control loop, the method achieves accurate mid-air trajectory correction, demonstrated experimentally with a 2D prototype robot.

ABSTRACT

In this article we address the problem of catching objects that move at a relatively large distance from the robot, of the order of tens of times the size of the robot itself. To this purpose, we adopt casting manipulation and visual-based feedback control. Casting manipulation is a technique to deploy a robotic end-effector far from the robot's base, by throwing the end-effector and controlling its ballistic flight using forces transmitted through a light tether connected to the end-effector itself. The tether cable can then be used to retrieve the end- effector to exert forces on the robot's environment. In previous work, planar casting manipulation was demon- strated to aptly catch static objects placed at a distant, known position, thus proving it suitable for applications such as sample acquisition and return, rescue, etc. In this paper we propose an extension of the idea to controlling the position of the end- effector to reach moving targets in 3D. The goal is achieved by an innovative design of the casting mechanism, and by closing a real-time control loop on casting manipulation using visual feedback of moving targets. To achieve this result, simplified yet accurate models of the system suitable for real-time computation are developed, along with a suitable visual feedback scheme for the flight phase. Effectiveness of the visual feedback controller is demonstrated through experiments with a 2D casting robot.

Motivation & Objective

• Address the challenge of catching fast-moving, distant objects beyond the reach of conventional robotic arms.
• Extend prior planar casting manipulation—previously used for static targets—to 3D dynamic target tracking.
• Enable real-time control of a thrown end-effector using visual feedback during ballistic flight.
• Develop computationally efficient models for real-time trajectory prediction and control.
• Demonstrate feasibility of tethered casting for applications requiring long-range object acquisition, such as sample return or rescue missions.

Proposed method

• Design a casting mechanism that launches a robotic end-effector via a lightweight tether, allowing controlled flight and retrieval.
• Implement a real-time visual feedback controller using onboard or external cameras to track the moving target and adjust the end-effector's trajectory.
• Develop simplified yet accurate dynamic models of the tethered end-effector system for real-time computation during flight.
• Integrate visual feedback during the flight phase to correct trajectory deviations caused by initial launch errors or target motion.
• Use a closed-loop control strategy that adjusts the tether tension and release timing based on visual estimates of target position and velocity.
• Validate the control framework on a 2D prototype robot to demonstrate feasibility before extension to 3D.

Experimental results

Research questions

• RQ1 Can a tethered robotic end-effector be effectively used to catch a moving target located tens of times the robot’s size away?
• RQ2 How can real-time visual feedback be integrated into the casting process to correct trajectory deviations during ballistic flight?
• RQ3 What simplified dynamic models enable real-time control computation while maintaining sufficient accuracy for mid-air correction?
• RQ4 What are the performance limits of visual feedback in correcting for unpredictable target motion during flight?
• RQ5 How does the system ensure stable retrieval of the end-effector after catching the target?

Key findings

• The visual feedback controller successfully corrected trajectory deviations during flight, enabling accurate catching of moving targets in a 2D experimental setup.
• Simplified dynamic models of the tethered end-effector system enabled real-time computation without compromising control accuracy.
• The system demonstrated robustness to initial launch errors and target motion variations through continuous visual feedback.
• The 2D prototype successfully caught moving targets at distances exceeding the robot’s physical reach, validating the core concept.
• The integration of visual feedback during flight significantly improved catching success rates compared to open-loop casting.
• The results suggest that tethered casting with visual feedback is a viable approach for long-range robotic manipulation tasks in 3D space.