ShapeForce: Low-Cost Soft Robotic Wrist for Contact-Rich Manipulation
Jinxuan Zhu, Zihao Yan, Yangyu Xiao, Jingxiang Guo, Chenrui Tie, Xinyi Cao, Yuhang Zheng, Lin Shao
AI summary
Problem
Six-axis force-torque sensors are typically expensive and fragile, while existing low-cost alternatives often require specialized electronics or high-end sensors for calibration.
Approach
A 3D-printed compliant wrist that converts external forces into deformations, which are tracked via a wrist-mounted RGB camera using marker-based pose tracking to generate relative force-like signals.
Key results
- High linearity between deformation and ground-truth wrench with a mean R² of 0.9577
- Performance comparable to six-axis FT sensors in tasks like peg insertion, USB insertion, and bottle cap tightening
- Successful integration with both classical search-and-control policies and learning-based policies (ACT, Diffusion Policy)
- Extremely low fabrication cost using TPU and PLA materials (~$6)
Why it matters
It enables accessible and durable contact-feedback for robotic manipulation without the need for expensive hardware or complex calibration.
Abstract
Contact feedback is essential for contact-rich robotic manipulation, as it allows the robot to detect subtle interaction changes and adjust its actions accordingly. Six- axis force-torque sensors are commonly used to obtain contact feedback, but their high cost and fragility have discouraged many researchers from adopting them in contact-rich tasks. To offer a more cost-efficient and easy-accessible source of contact feedback, we present ShapeForce, a low-cost, plug- and-play soft wrist that provides force-like signals for contact- rich robotic manipulation. Inspired by how humans rely on relative force changes in contact rather than precise force magnitudes, ShapeForce converts external force and torque into measurable deformations of its compliant core, which are then estimated via marker-based pose tracking and converted into force-like signals. Our design eliminates the need for calibration or specialized electronics to obtain exact values, and instead focuses on capturing force and torque changes sufficient for enabling contact-rich manipulation. Extensive experiments across diverse contact-rich tasks and manipulation policies demonstrate that ShapeForce delivers performance comparable to six-axis force-torque sensors at an extremely low cost. More details of this project can be found at our project page: https://shapeforce.github.io/.