Developing wearable platforms for unconstrained monitoring of limb movements has been an active recent topic of research due to potential applications such as clinical and athletic performance evaluation. However, practicality of these platforms might be affected by the dynamic and complexity of movements as well as characteristics of the surrounding environment. This paper addresses such issues by proposing a novel method for obtaining kinematic information of joints using a custom-designed wearable platform. The proposed method uses data from two gyroscopes and an array of textile stretch sensors to accurately track three-dimensional movements, including extension, flexion, and rotation, of a joint. More specifically, gyroscopes provide angular velocity data of two sides of a joint, while their relative orientation is estimated by a machine learning algorithm. An Unscented Kalman Filter (UKF) algorithm is applied to directly fuse angular velocity/relative orientation data and estimate the kinematic orientation of the joint. Experimental evaluations were carried out using data from 10 volunteers performing a series of predefined as well as unconstrained random three-dimensional trunk movements. Results show that the proposed sensor setup and the UKF-based data fusion algorithm can accurately estimate the orientation of the trunk relative to pelvis with an average error of less than 1.72 degrees in predefined movements and a comparable accuracy of 3.00 degrees in random movements. Moreover, the proposed platform is easy to setup, does not restrict body motion, and is not affected by environmental disturbances. This study is a further step towards developing user-friendly wearable sensor systems than can be readily used in indoor and outdoor settings without requiring bulky equipment or a tedious calibration phase.

Human-robot collaboration in industrial settings calls for implementing safety measures to ensure there is no risk to humans working in such an environment. In human-robot physical collaboration, an object or a load is handled by both human and the robot. Developing a safety framework for the robot is a requirement for preventing collisions during performing a task. In this paper, force myography (FMG) data are used to develop a control scheme for the robot such that it can work with the human worker while avoiding collisions. Force myography quantifies the activities of human muscles when applying forces to handle an object. A neural network-based approach is then used to select the most informative features of the FMG signal. The developed control scheme incorporates the FMG data and the robot dynamics to obtain a prediction about the next step of the cooperation task and to plan the robot motion accordingly. The proposed approach is evaluated experimentally in real time in a moving objects task which requires appropriate complementary actions from the robot and the human user. The results of this study show that the proposed scheme can successfully plan the robot motion based on the actions of the human user.

Lack of dexterous control over the position of a catheter's distal tip and not having any feedback from the quality of tip - tissue contact are among the factors that make the conventional catheter-based method of performing cardiac ablation very challenging. To resolve these issues, in this paper, we present a robotic catheter manipulation system that accommodates a conventional ablation catheter, places the ablation tip at the desired target and reports the forces that the tip exerts on the environment in real-time. In this system, the manual proximal handle is replaced with a mechanism that is capable of measuring the tension force along the pull-wire while actuating it to flex the distal shaft of the catheter. The placement of force/pressure sensors at the distal end of the catheter is avoided by developing a model-based force estimation technique using the measured tension force and information on the position and orientation of the distal tip. The developed system is further enhanced with an interface to assist the user in placing the catheter tip at the desired location while providing him/her with a real-time measure of the contact force. Extensive experiments show that using the proposed robotic system, the catheter tip is positioned within ±1 mm of the designated target and contact forces are reported in real-time with an accuracy of 3 gf.

Cardiac ablation using flexible catheters is a common interventional procedure for treating cardiac arrhythmia. This procedure is performed under image guidance and the contact force between the ablation tip and the heart tissue is one of the factors that greatly impacts the efficacy of the ablation procedure. This paper investigates the feasibility of estimating the force that the catheter tip exerts on the heart tissue by monitoring the changes in the shape of the deflectable distal shaft of the catheter (henceforth called the “deflectable shaft” or the “shaft” of the catheter). It is shown that variations in the shaft curvature provide information about how much force the catheter tip is exerting at its point of contact. Consequently, an index is defined for determining the range of contact forces based on the shaft curvature. Experimental results show that the defined index can correctly detect the range of applied contact forces in more than 80% of the cases. This study proves that the flexibility of the deflectable shaft provides a means of estimating contact forces exerted by the catheter tip.

Over the past few decades, catheter-based cardiac ablation has been the first surgical option for treatment of arrhythmia. In order to have an effective ablation procedure, after positioning the catheter at the desired location inside the heart chamber, a consistent tip/tissue contact should be maintained during the whole procedure. With the goal of implementing hybrid force/position control of the catheter tip during the ablation procedure, this paper studies how the catheter tip deflects when forces are applied. A pseudo-rigid-body 3R model for the catheter tip is introduced. The model performance is evaluated through extensive experiments and it is shown that the proposed model can estimate the shape of the bending section of the ablation catheter if force information is available. This model does not require extensive knowledge of the catheter internal structure. Moreover, the well-established static equations are simple to understand and solve, making this model a convenient choice for developing a control system.

The increasing popularity of catheter-based ablation therapy in treating cardiac arrhythmia has motivated researchers to seek new techniques to improve the accuracy and efficiency of such procedures. After guiding the catheter through the vessels into the heart chambers, precise positioning of the catheter tip and consistent tool/tissue contact force are the two factors that greatly affect the ablation outcome. Implementing force/position control of the catheter tip will improve the efficacy of cardiac ablation procedures immensely. This paper proposes a model-based force control system to ensure a desired contact force at the distal tip, without directly measuring the force applied at the tip. In this regard, it is studied how the displacement of the proximal handle of a common 7-Fr pull-wire ablation catheter relates to the change of angle at its distal tip. The resulting mapping together with a mapping that relates the forces at the distal tip to the tip shape are used in developing a control system that ensures a desired contact force at the tip. This paper also introduces an optical strain sensor that can be used without modification in the manufacture of present day ablation catheters. This strain sensor completes the feedback loop of the control system through integration with the shape to force model. Performance of the control system is evaluated experimentally and the results suggest that model-based control of steerable catheters is feasible for catheter ablation. The proposed control system can be employed on a conventional ablation catheter following a fairly simple calibration step.

Catheter-based cardiac ablation is an interventional treatment for heart arrhythmias. Pull-wire steerable catheters are guided to the heart chambers through the vasculature in order to deliver energy to destroy faulty electrical pathways in the heart. The effectiveness of this treatment is dependent on the accuracy of positioning the catheter tip at the target location and also on maintaining contact with the target while the heart is beating. Therefore, it is desirable to perform hybrid force/position control of the catheter tip. We have studied the problem of modeling the distal part of a steerable catheter using beam theory and have developed and validated a static force-deflection model through extensive experiments. It is shown that the model can estimate the shape of the bending section of a catheter using force information and without requiring extensive knowledge of the catheter's internal structure.