External contact force is one of the most significant information for the robots to model, control, and safely interact with external objects. For continuum robots, it is possible to estimate the contact force based on the measurements of robot configurations, which addresses the difficulty of implementing the force sensor feedback on the robot body with strict dimension constraints. In this paper, we use local curvatures measured from fiber Bragg grating sensors (FBGS) to estimate the magnitude and location of single or multiple external contact forces. A simplified mechanics model is derived from Cosserat rod theory to compute continuum robot curvatures. Least-square optimization is utilized to estimate the forces by minimizing errors between computed curvatures and measured curvatures. The results show that the proposed method is able to accurately estimate the contact force magnitude (error: 5.25\% -- 12.87\%) and locations (error: 1.02\% -- 2.19\%). The calculation speed of the proposed method is validated in MATLAB. The results indicate that our approach is 29.0 -- 101.6 times faster than the conventional methods. These results indicate that the proposed method is accurate and efficient for contact force estimations.
Department of Automation, Tsinghua University（清华大学自动化系）
The continuum robot has attracted more attention for its flexibility. Continuum robot kinematics models are the basis for further perception, planning, and control. The design and research of continuum robots are usually based on the assumption of piecewise constant curvature (PCC). However, due to the influence of friction, etc., the actual motion of the continuum robot is approximate piecewise constant curvature (APCC). To address this, we present a kinematic equivalent model for continuum robots, i.e. APCC 2L-5R. Using classical rigid linkages to replace the original model in kinematic, the…
Department of Automation, Tsinghua University（清华大学自动化系）
Continuum robots are typically slender and flexible with infinite freedoms in theory, which poses a challenge for their control and application. The shape sensing of continuum robots is vital to realise accuracy control. This letter proposed a novel general real-time shape sensing framework of continuum robots based on the piecewise polynomial curvature (PPC) kinematics model. We illustrate the coupling between orientation and position at any given location of the continuum robots. Further, the coupling relation could be bridged by the PPC kinematics. Therefore, we propose to estimate the shap…
College of Engineering, Peking University（北京大学工学院）；School of Mechanical Engineering, Northwestern Polytechnical University（西北工业大学机械工程学院）；School of Astronautics, Northwestern Polytechnical University（西北工业大学航空学院）
The Chinese University of Hong Kong（香港中文大学）；Hong Kong Center for Logistics Robotics（香港物流机器人中心）；Soochow University（苏州大学）
In this paper, we present a novel and generic data-driven method to servo-control the 3-D shape of continuum and soft robots embedded with fiber Bragg grating (FBG) sensors. Developments of 3-D shape perception and control technologies are crucial for continuum robots to perform the tasks autonomously in surgical interventions. However, owing to the nonlinear properties of continuum robots, one main difficulty lies in the modeling of them, especially for soft robots with variable stiffness. To address this problem, we propose a versatile learning-based adaptive controller by leveraging FBG sha…
Indian Institute of Science（印度科学研究所）；FeatherDyn Pvt. Ltd.（FeatherDyn私人有限公司）
Continuum robots are becoming increasingly popular for applications which require the robots to deform and change shape, while also being compliant. A cable-driven continuum robot is one of the most commonly used type. Typical cable driven continuum robots consist of a flexible backbone with spacer disks attached to the backbone and cables passing through the holes in the spacer disks from the fixed base to a free end. In most such robots, the routing of the cables are straight or a smooth helical curve. In this paper, we analyze the experimental and theoretical deformations of a 3D printed co…
Many have explored the application of continuum robot manipulators for minimally invasive surgery, and have successfully demonstrated the advantages their flexible design provides -- with some solutions having reached commercialisation and clinical practice. However, the usual high complexity and closed-nature of such designs has traditionally restricted the shared development of continuum robots across the research area, thus impacting further progress and the solution of open challenges. In order to close this gap, this paper introduces ENDO, an open-source 3-segment continuum robot manipula…
Vision-based control provides a significant potential for the end-point positioning of continuum robots under physical sensing limitations. Traditional visual servoing requires feature extraction and tracking followed by full or partial pose estimation, limiting the controller's efficiency. We hypothesize that employing deep learning models and implementing direct visual servoing can effectively resolve the issue by eliminating such intermediate steps, enabling control of a continuum robot without requiring an exact system model. This paper presents the control of a single-section tendon-drive…
Efficient RRT*-based Safety-Constrained Motion Planning for Continuum Robots in Dynamic Environments
Southern University of Science and Technology（南方科技大学）；Jiaxing Research Institute, Southern University of Science and Technology（南方科技大学嘉兴研究院）；City University of Hong Kong（香港城市大学）
Cable-driven Continuum Robotics: Proprioception via Proximal-integrated Force Sensing
The Chinese University of Hong Kong（香港中文大学）；T Stone Robotics Institute（T Stone机器人研究所）；Department of Mechanical and Automation Engineering（机械与自动化工程系）；Shun Hing Institute of Advanced Engineering（顺兴先进工程研究院）；Multi-Scale Medical Robotics Center（多尺度医疗机器人中心）；Curve Robotics Limited（Curve机器人有限公司）
Intelligence and Motion Models of Continuum Robots: an Overview
IHP – Leibniz-Institut für innovative Mikroelektronik（IHP – 莱布尼茨创新微电子研究所）；BTU Cottbus-Senftenberg（科特布斯-森夫滕贝格勃兰登堡工业大学）；Taras Shevchenko National University of Kyiv（基辅塔拉斯·舍甫琴科国立大学）；Bogomoletz Institute of Physiology（博戈莫列茨生理学研究所）
Soft robots are promising for manipulation tasks thanks to their compliance, safety, and high degree of freedom. However, the commonly used bidirectional continuum segment design means soft robotic manipulators only function in a limited hemispherical workspace. This work increases a soft robotic arm's workspace by designing, fabricating, and controlling an additional soft prismatic actuator at the base of the soft arm. This actuator consists of pneumatic artificial muscles and a piston, making the actuator back-driveable. We increase the task space volume by 116\%, and we are now able to perf…
Shape control of simulated multi-segment continuum robots via Koopman operators with per-segment projection
Department of Electrical Engineering and Computer Science University of Michigan, Ann Arbor, Michigan 48109, USA（密歇根大学电气工程与计算机科学系）；School for Engineering of Matter, Transport and Energy Arizona State University, Tempe, Arizona 85281, USA（亚利桑那州立大学工程物质、运输与能源学院）
The inverse kinematics (IK) problem of continuum robots has been investigated in depth in the past decades. Under the constant-curvature bending assumption, closed-form IK solution has been obtained for continuum robots with variable segment lengths. Attempting to close the gap towards a complete solution, this paper presents an efficient solution for the IK problem of 2-segment continuum robots with one or two inextensible segments (a.k.a, constant segment lengths). Via representing the robot's shape as piecewise line segments, the configuration variables are separated from the IK formulation…
Embedded Flexible Circumferential Sensing for Real-Time Intraoperative Environmental Perception in Continuum Robots
Shenzhen Key Laboratory of Robotics Perception and Intelligence（机器人感知与智能深圳重点实验室）；Southern University of Science and Technology（南方科技大学）；Department of Electronic and Electrical Engineering（电子与电气工程系）；Department of Electrical Engineering（电气工程系）；Institute of Robotics and Intelligent Systems（机器人与智能系统研究院）
The purpose of this research is to design, fabricate and test a tendon driven a continuum soft robot with three modular segments, each of which has a tunable stiffness enabled by layer jamming technology. Compared with previous studies, the robotic arm design of this project has a modular structure, which means the length of the robotic arm can be adjusted by addition of extra arm modules/segments to the existing robotic prototype. Furthermore, the new arm prototype supports motion within a 3-dimensional space. To achieve the goals, the design and fabrication for the variable stiffness robotic…
We present an orientation adaptive controller to compensate for the effects of highly constrained environments on continuum manipulator actuation. A transformation matrix updated using optimal estimation techniques from optical flow measurements captured by the distal camera is composed with any Jacobian estimation or kinematic model to compensate for these effects. By utilizing domain knowledge to define the structure of this matrix, fewer parameters need to be estimated and a stable controller can be guaranteed. The algorithm is tested on a custom robotic catheter and convergence is shown bo…
Three-dimensional Morphological Reconstruction of Millimeter-Scale Soft Continuum Robots based on Dual-Stereo-Vision
Stanford University（斯坦福大学）；CUHK Shenzhen Research Institute（香港中文大学（深圳）研究院）；The Chinese University of Hong Kong（香港中文大学）；College of Computer Science and Electronic Engineering, Hunan University（湖南大学计算机与电子工程学院）
Plant-inspired behavior-based controller to enable reaching in redundant continuum robot arms
The BioRobotics Institute, Sant’Anna School of Advanced Studies（圣安娜高等研究院生物机器人研究所）；Department of Mechanical Engineering, National University of Singapore（新加坡国立大学机械工程系）
A Unified Multi-Dynamics Framework for Perception-Oriented Modeling in Tendon-Driven Continuum Robots
Robotics Department, Mohamed bin Zayed University of Artificial Intelligence (MBZUAI)（Mohamed bin Zayed大学人工智能研究院机器人部门）；Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China (USTC)（中国科学技术大学微尺度物理科学国家级研究中心）
Increasing Resilience of Continuum Robots via Motion Planning Algorithms
IHP – Leibniz-Institut für innovative Mikroelektronik（莱布尼茨创新微电子研究所）；BTU Cottbus-Senftenberg（科特博斯-塞芬堡工业大学）；Technical Center, National Academy of Sciences of Ukraine（乌克兰国家科学院技术中心）
Continuum Robot State Estimation with Actuation Uncertainty
Department of Electrical and Computer Engineering and Department of Computer Science, Vanderbilt University（电气与计算机工程系和计算机科学系，范德比尔特大学）；Kahlert School of Computing and Robotics Center, University of Utah（计算与机器人中心，犹他大学）；NVIDIA（英伟达）
Model-less Active Compliance for Continuum Robots using Recurrent Neural Networks
Queensland University of Technology（昆士兰科技大学）；Nvidia AI technology centre（英伟达人工智能技术中心）；Airdoc Research（Airdoc研究院）；Monash University（莫纳什大学）；University of New South Wales（新南威尔士大学）
Continuum Robot Localization using Distributed Time-of-Flight Sensors
University of Toronto Robotics Institute, Canada（多伦多大学机器人研究所，加拿大）；Oxford Robotics Institute, University of Oxford, UK（牛津大学机器人研究所，英国）；Toronto Metropolitan University, Canada（多伦多 Metropolitan 大学，加拿大）
