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Haofeng Chen

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4 papers

1 author row

IROS Conference 2025 Conference Paper

Enhancing Tactile Sensing in Robotics Using Null-Space Diffusion Model with EIT-based Sensors

Qilin Zhang
Haofeng Chen
Xuanxuan Yang
Gang Ma
Xiaojie Wang

Robotic tactile sensors based on Electrical Impedance Tomography (EIT) have gained great attention in robotic sensing applications due to their features such as no internal wiring, "all-in-one" structure, and continuous sensing capabilities. However, the effectiveness of EIT-based tactile sensors is hampered by limited spatial resolution and artifacts in the reconstructed images. To address these challenges, various iterative optimization methods based on spatial regularizations and model-based methods have been proposed. In this study, a new EIT reconstruction method using null-space decomposition based on a diffusion model (NSDM) is proposed. Specifically, NSDM consists of a forward diffusion process that first gradually adds Gaussian noise to a clean conductivity image, followed by a backward process that learns to predict the noise that should be removed during each sampling step, utilizing a prior to ensure that the denoising process does not deviate from the correct direction. NSDM requires no training, no optimization, and only requires a pre-prepared diffusion model. Experimental results (both simulation and actual tests) demonstrate that the proposed method outperforms existing generation methods and provides higher quality reconstruction, providing a new solution for robotic tactile sensing in real scenarios.

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ICRA Conference 2024 Conference Paper

Enhancing Tactile Sensing in Robotics: Dual-Modal Force and Shape Perception with EIT-based Sensors and MM-CNN

Haofeng Chen
Xuanxuan Yang
Gang Ma 0008
Yucheng Wang
Xiaojie Wang 0004

Electrical Impedance Tomography (EIT)-based tactile sensors offer durability, scalability, and cost-effective manufacturing. However, simultaneously reconstructing force and shape from boundary measurements remains challenging due to EIT’s inherent location dependencies and image artifacts. This study presents a model-driven multimodal convolutional neural network (MM-CNN) for joint EIT-based force and shape sensing. The hybrid approach combines physics-inspired voltage preprocessing with an attention-based network to overcome EIT’s limitations. The preprocessing network applies a linearized one-step inverse solution with Tikhonov regularization to convert raw boundary voltage into a noise-reduced 2D image. The image reconstruction network uses an attention mechanism to focus on salient features, addressing location dependency issues. Quantitative metrics show that MM-CNN outperforms traditional EIT algorithms like NOSER and TV, reducing location dependency and improving shape discrimination. MM-CNN enables unified force and shape modalities, validated through real-contact experiments, enhancing EIT tactile systems for human-robot interaction by incorporating physical knowledge with deep learning.

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IROS Conference 2024 Conference Paper

Pseudo-Domain Adversarial Networks with Electrical Impedance Tomography for Electrode Offset Error

Gengchen Xu
Haofeng Chen
Xuanxuan Yang
Gang Ma 0008
Xiaojie Wang 0004

This paper propose a novel transfer learning approach, Pseudo-Domain Adversarial Network (PDAN), to tackle the issue of electrode displacement in Electrical Impedance Tomography (EIT). Electrode displacement, caused by human movement or improper operation, significantly affects the accuracy of EIT by introducing data errors. Existing solutions either modify the electrode assembly at a high cost or employ recognition algorithms that require retraining from scratch. To overcome these limitations, our work leverages the power of transfer learning to enhance model performance in the target domain by utilizing knowledge from a related task in the source domain. PDAN extends the capabilities of deep adversarial learning by incorporating noisy images to simulate post-electrode rotation scenarios, aiding in the reduction of negative impacts caused by minor electrode displacements. Our method demonstrates superior performance in classifying leg posture data, achieving around 90% accuracy, and proving robust against sensor electrode offset. Experimental results across various datasets validate the effectiveness of PDAN, indicating its potential in addressing complex real-world situations with improved generalization capabilities.

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IROS Conference 2018 Conference Paper

Towards Material Classification of Scenes Using Active Thermography

Haoping Bai
Tapomayukh Bhattacharjee
Haofeng Chen
Ariel Kapusta
Charles C. Kemp

By briefly heating the local environment with a heat lamp and observing what happens with a thermal camera, robots could potentially infer properties of their surroundings. However, this form of active thermography introduces large signal variations compared to traditional active thermography, which has typically been used to characterize small regions of materials in carefully controlled settings. We demonstrate that a data-driven approach with modern machine learning methods can be used to classify material samples over relatively large surface areas and variable distances. We also introduce the use of z-normalization to improve material classification and reduce variation due to distance and heating intensity. Our best performing algorithm achieved an overall accuracy of 77. 7% for multi-class classification among 12 materials placed at varying distances (20 cm, 30 cm, and 40 cm). The observations were made for 5 seconds with 1s of heating and 4s of cooling. We also provide a demonstration of performance with a multi-material scene.

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