1-DOF Teleoperated Gripper with Realistic Force Feedback

Project team members: Quynh Nguyen, Ke Wang, Loïc Poisson, Max Schaldach

This project focuses on designing and building a 1-DOF teleoperated gripper with realistic force feedback. The user operates a leader gripper, and the follower gripper reproduces the motion while reflecting contact forces back to the user. Our original proposal included a machine-learning comparison, but after discussion with the teaching team we narrowed the scope to the haptics hardware itself. This pivot lets us concentrate on building a cleaner, more transparent, and more convincing force-feedback device within the available time.

Introduction

The educational goal of this project is to explore the mechanics of haptic interaction in a simple but meaningful teleoperation system. A 1-DOF gripper is a good testbed because it reduces the control problem to the essential question of grasping and force reflection, without the added complexity of a multi-DOF arm or a learning-based policy stack.

Our updated goal is to build a follower gripper that provides realistic force feedback during closing and contact. In the final system, the user should feel the onset of grasping and resistance from the remote object through the leader interface. This makes the project directly relevant to teleoperation.

Background

Bilateral teleoperation has a long history in haptics research. Lawrence’s work on stability and transparency established the classic tradeoff between accurate force reflection and closed-loop stability. Niemeyer and Slotine later showed how time-delay compensation can preserve passivity in telemanipulation systems, which is central to any force-reflecting setup.

For grasping specifically, prior work has shown that force feedback improves task performance and user control. Wildenbeest et al. studied the role of haptic feedback quality in teleoperated assembly tasks, while Khurshid et al. showed that grip-force feedback improves teleoperated pick-and-place performance. Romano et al. demonstrated how tactile sensing can support grasp control, which motivates our inclusion of force sensing in the follower gripper.

These papers support the core design choice of this project: instead of relying on vision alone, we want a physical teleoperation device that makes force a first-class signal.

Methods

System Overview

Our system is a 1-DOF teleoperated gripper with a leader-follower structure. The follower is the main focus of the build. It will open and close linearly, with two claws constrained to move along rails. A motorized drive will translate motion into grasping action, and force sensors will measure contact so that the load can be reflected back through the system.

The design goal is not maximal degrees of freedom, but high transparency and smooth motion. We want the user to experience a clear relationship between hand motion, gripper closure, and contact force.

Hardware Design and Implementation

The follower gripper will use two claws mounted on linear rails with bearings to minimize friction. This allows the closing motion to remain as clean and direct as possible. The actuation concept is a gear-and-rack style transmission driven by an encoded stepper motor. The encoder gives us better position tracking and should help with repeatable motion and control.

We also plan to integrate force sensors into the grasp path so that the follower can detect contact force during closure. The main mechanical subsystems we identified are: - claws - base frame - sensor holder - motor shaft / drive assembly - guiding rails and bearings - housing

System Analysis and Control

The control system will map leader motion to follower motion and reflect measured contact force back to the user. Our goal here is not to build a sophisticated autonomy stack, but to make the haptic loop feel physically believable.

At a minimum, the code will need to: 1. read leader input 2. command the follower motor position 3. read force sensor values 4. convert sensed contact into reflected resistance 5. maintain stable motion without excessive backlash or friction artifacts

Because the project scope was narrowed, the emphasis is on making the basic teleoperation loop feel good and physically consistent rather than on learning-based autonomy.

Demonstration / Application

The primary demonstration will be a user interacting with the teleoperated follower gripper and feeling the transition from free motion to object contact. If time permits, we would also like to explore a more natural leader mechanism that mimics the thumb-index closing motion more closely, rather than using only a linear interface.

The main application is a compact haptic gripper platform that demonstrates force reflection in a simple and understandable way.

Results

At the checkpoint stage, the main result is that we successfully re-scoped the project into a feasible and more focused haptics build. We now have a concrete mechanical concept, a subsystem breakdown, and a division of labor for implementation.

We have not yet completed the final physical device, so there are no practical results yet.

Future Work

The next steps are to finish the follower housing and claw design, integrate the motor and force sensors, and implement the control code. After that, we will test whether the gripper motion feels smooth, whether the sensed force is reflected clearly, and whether the device has acceptable transparency.

If time allows, we may build a leader mechanism with angular closing motion to better resemble the human thumb and index finger. That would improve the realism of the interaction, but the follower gripper remains the priority.

Acknowledgments

We thank Allison for helping us narrow the scope of the original proposal and steer the project toward a more realistic and implementable haptics build.

Files

CAD / drawings: TBD Major components and approximate costs: TBD

References

[1] D. A. Lawrence, “Stability and Transparency in Bilateral Teleoperation,” IEEE Transactions on Robotics and Automation, vol. 9, no. 5, pp. 624–637, 1993.

[2] G. Niemeyer and J.-J. E. Slotine, “Telemanipulation with Time Delays,” The International Journal of Robotics Research, vol. 23, no. 9, pp. 873–890, 2004.

[3] J. G. W. Wildenbeest, D. A. Abbink, C. J. M. Heemskerk, F. C. T. van der Helm, and H. Boessenkool, “The Impact of Haptic Feedback Quality on the Performance of Teleoperated Assembly Tasks,” IEEE Transactions on Haptics, vol. 6, no. 2, pp. 242–252, 2013.

[4] R. P. Khurshid, N. T. Fitter, E. A. Fedalei, and K. J. Kuchenbecker, “Effects of Grip-Force, Contact, and Acceleration Feedback on a Teleoperated Pick-and-Place Task,” IEEE Transactions on Haptics, vol. 10, no. 1, pp. 40–53, 2017.

[5] J. M. Romano, K. Hsiao, G. Niemeyer, S. Chitta, and K. J. Kuchenbecker, “Human-Inspired Robotic Grasp Control with Tactile Sensing,” IEEE Transactions on Robotics, vol. 27, no. 6, pp. 1067–1079, 2011.

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Appendix: Project Checkpoints

Checkpoint 1

At the time of Checkpoint 1, our project underwent a large pivot. Our original proposal combined bilateral teleoperation with a machine-learning comparison, but after discussing scope with the teaching team, we realized that the full plan would be too ambitious for the time available. In particular, the original concept would have required a more complex multi-DOF gripper and a substantial ML effort, which would have split our attention between two large engineering tasks.

We therefore re-scoped the project to focus on the haptics hardware itself: a 1-DOF teleoperated gripper with realistic force feedback. This change is an improvement in scope because it lets us concentrate on the core question of force reflection and device transparency. We decided to prioritize a cleaner mechanical design rather than trying to force a robotics-learning component into the project.

The main checkpoint goal was to agree on a mechanical architecture and define clear work assignments for the team. We accomplished that goal. Based on our design sketches, the follower will use a linear claw motion constrained by rails and bearings, with a motorized transmission and force sensing in the grasp path. We also identified the main build components: claws, base frame, sensor holder, motor shaft, and housing. The design intent is to minimize friction so that the device feels smooth and transmits force cleanly.

We divided the implementation work clearly: Max is handling assembly and force sensors, Quynh is working on housing, Ke is handling coding and electronics, and Loïc is responsible for the claw design. At this stage, we have not completed the final physical build, but the project is now much more concrete and feasible. Our next milestone is to finish the follower hardware until May 19, integrate the sensors and motor, and begin implementing the control loop.

Checkpoint 2

Here you will write a few paragraphs about what you accomplished in the project so far. Include the checkpoint goals and describe which goals were met (and how), which were not (what were the challenges?), and any change of plans for the project based on what you learned. Include images and/or drawings where appropriate.

Example Video: https://www.youtube.com/watch?v=i_aLBql4Ufo