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Author: Shoujie Li, Mingshan He, Wenbo Ding, Linqi Ye, Xueqian Wang, Junbo Tan, Jinqiu Yuan,Xiao-Ping Zhang
Manual oropharyngeal (OP) swab sampling is an intensive and risky task. In this article, a novel OP swab sampling device of low cost and high compliance is designed by combining the visuo-tactile sensor and the pneumatic actuator-based gripper. Here, a concave visuo-tactile sensor called CoTac is first proposed to address the problems of high cost and poor reliability of traditional multi-axis force sensors. Besides, by imitating the doctor's fingers, a soft pneumatic actuator with a rigid skeleton structure is designed, which is demonstrated to be reliable and safe via finite element modeling and experiments. Furthermore, we propose a sampling method that adopts a compliant control algorithm based on the adaptive virtual force to enhance the safety and compliance of the swab sampling process. The effectiveness of the device has been verified through sampling experiments as well as in vivo tests, indicating great application potential. The cost of the device is around 30 US dollars and the total weight of the functional part is less than 0.1 kg, allowing the device to be rapidly deployed on various robotic arms.
Structural Design
According to the function, the device can be divided into two parts, i.e., the visuo-tactile based sensing part and the pneumatic gripping part. To improve the tactile perception capability of the OP sampling devices, we present a concave structured tactile sensor named CoTac, which adopts a visuo-tactile sensing method with low cost and high resolution. The gripping part mimics the state of a doctor's fingers during sampling. Based on our survey with the medical staff, we found that the human finger parallels the gripping structure and provides better stability and control accuracy.
Algorithm Design
How to balance comfort and effectiveness has been the focus of research on OP swab sampling robots. Due to the small space in the oral cavity and the obstruction of the hand, it is difficult to accurately determine the detection position based on vision. For the medical staff, a large part of the information is obtained through tactile sensation when performing the OP swab sampling. Therefore, we propose a robotic OP swab sampling method based on the CoTac sensor and admittance control to achieve safe and stable sampling. The method includes a sampling position detection algorithm, a tactile information extraction algorithm, and a compliant control algorithm, of which the flow chart is described in the above figure.
Experiment Evaluation
To test the effectiveness of the proposed OP swab sampling device, we design a series of experiments in a systematic manner, including the gripping force experiment, swab gripping experiment, force compliance experiment, sampling effectiveness experiment, and in vivo experiment.
video.mp4Conclusion
In this article, we propose a low-cost OP swab sampling device. In the sensing part, we propose a novel concave tactile sensor named CoTac, which has a large detection area as well as high sensitivity compared to the traditional force sensors. The device has a rigidly wrapped pneumatic soft structure in the gripping part, which not only generates an effective gripping force but also has high compliance, eliminating the potential threat to human safety. In addition, since the structure does not have an electric actuator, the whole device can be directly sprayed for disinfection to prevent cross-infection. For the sampling method, an OP sampling position detection algorithm, a tactile information extraction algorithm, and an AVF compliant control algorithm are proposed. Overall, we use both hardware compliance and algorithmic compliance to ensure the safety of the sampling process. The effectiveness of the device has been verified through sampling experiments as well as in vivo tests, indicating great application potential. The cost of the device is around 30 USD and the total weight of the functional part is 0.1 kg, allowing the device to be rapidly deployed on various robotic arms.
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