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Experimental Characterization of Fingertip Trajectory following for a 3-DoF Series-Parallel Hybrid Robotic Finger

Nicholas Baiata, Nilanjan Chakraborty

TL;DR

This work addresses the challenge of precise fingertip trajectory control in a compact, multi-DoF hand by implementing a physically realized 3-DoF linkage-driven finger with analytic forward kinematics and a closed-form Jacobian. Using RMRC, the authors demonstrate millimeter-scale fingertip tracking accuracy across diverse trajectories, validating task-space control in a hardware finger. The study provides detailed planning and measurement methodologies, quantitative tracking results, and a comprehensive kinematic derivation in supplementary materials, establishing a benchmark for in-hand manipulation with linkage-driven designs. Collectively, the results advance dexterous manipulation by showing that task-space trajectory tracking is feasible in a compact, analytically tractable finger, paving the way for multi-finger hands and advanced manipulation tasks.

Abstract

Task-space control of robotic fingers is a critical enabler of dexterous manipulation, as manipulation objectives are most naturally specified in terms of fingertip motions and applied forces rather than individual joint angles. While task-space planning and control have been extensively studied for larger, arm-scale manipulators, demonstrations of precise task-space trajectory tracking in compact, multi-DoF robotic fingers remain scarce. In this paper, we present the physical prototyping and experimental characterization of a three-degree-of-freedom, linkage-driven, series-parallel robotic finger with analytic forward kinematics and a closed-form Jacobian. A resolved motion rate control (RMRC) scheme is implemented to achieve closed-loop task-space trajectory tracking. We experimentally evaluate the fingertip tracking performance across a variety of trajectories, including straight lines, circles, and more complex curves, and report millimeter-level accuracy. To the best of our knowledge, this work provides one of the first systematic experimental demonstrations of precise task-space trajectory tracking in a linkage-driven robotic finger, thereby establishing a benchmark for future designs aimed at dexterous in-hand manipulation.

Experimental Characterization of Fingertip Trajectory following for a 3-DoF Series-Parallel Hybrid Robotic Finger

TL;DR

This work addresses the challenge of precise fingertip trajectory control in a compact, multi-DoF hand by implementing a physically realized 3-DoF linkage-driven finger with analytic forward kinematics and a closed-form Jacobian. Using RMRC, the authors demonstrate millimeter-scale fingertip tracking accuracy across diverse trajectories, validating task-space control in a hardware finger. The study provides detailed planning and measurement methodologies, quantitative tracking results, and a comprehensive kinematic derivation in supplementary materials, establishing a benchmark for in-hand manipulation with linkage-driven designs. Collectively, the results advance dexterous manipulation by showing that task-space trajectory tracking is feasible in a compact, analytically tractable finger, paving the way for multi-finger hands and advanced manipulation tasks.

Abstract

Task-space control of robotic fingers is a critical enabler of dexterous manipulation, as manipulation objectives are most naturally specified in terms of fingertip motions and applied forces rather than individual joint angles. While task-space planning and control have been extensively studied for larger, arm-scale manipulators, demonstrations of precise task-space trajectory tracking in compact, multi-DoF robotic fingers remain scarce. In this paper, we present the physical prototyping and experimental characterization of a three-degree-of-freedom, linkage-driven, series-parallel robotic finger with analytic forward kinematics and a closed-form Jacobian. A resolved motion rate control (RMRC) scheme is implemented to achieve closed-loop task-space trajectory tracking. We experimentally evaluate the fingertip tracking performance across a variety of trajectories, including straight lines, circles, and more complex curves, and report millimeter-level accuracy. To the best of our knowledge, this work provides one of the first systematic experimental demonstrations of precise task-space trajectory tracking in a linkage-driven robotic finger, thereby establishing a benchmark for future designs aimed at dexterous in-hand manipulation.

Paper Structure

This paper contains 17 sections, 32 equations, 11 figures, 3 tables, 2 algorithms.

Table of Contents

  1. INTRODUCTION
  2. Related Work
  3. Finger Construction and Operation
  4. Controller/Planner Design
  5. Joint Space Planner
  6. Task Space Planner
  7. Results
  8. Measuring Method
  9. Fingertip Trajectory Following Results
  10. Fingertip Path Following Results
  11. Further Validation of Tracking Error
  12. Summary and Future Work
  13. Supplementary Materials
  14. Deriving the Loop-Closure Equations
  15. Solving the Loop-Closure Equations
  16. ...and 2 more sections

Figures (11)

  • Figure 1: 3-DoF Series-Parallel robotic finger prototype with direct-driven abduction and linkage-driven flexion.
  • Figure 2: Anatomic comparison of 3-DoF series-parallel finger with a human finger.
  • Figure 3: Our 3-DoF series-parallel robotic finger dimensions ($23 \times 20 \times95$ mm) is comparable in size to the AIDIN Robotics finger ($20 \times 21.5 \times 101$ mm) and Shadow Robotics Finger ($20 \times 18 \times 100$ mm)
  • Figure 4: Square Path in the Flexion Plane at 10 mm/s
  • Figure 5: Circle Path in the Flexion Plane at 10 mm/s
  • ...and 6 more figures