Month: May 2016

Human-Compliant Body-Attached Soft Robots Towards Automatic Cooperative Ultrasound Imaging

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Abstract

Ultrasound imaging procedures are deemed as one of the most convenient and least invasive medical diagnostic imaging modalities and have been widely utilized in health care providers, which are expecting semiautomatic or fully-automatic imaging systems to reduce the current clinical workloads. This paper presents a portable and wearable soft robotic system which has been designed with the purpose of replacing the manual operation to cooperatively steer the ultrasound probe. This human-compliant soft robotic system, which is equipped with four separated parallel soft pneumatic actuators and is able to achieve movements in three directions. Vacuum suction force is introduced to attach the robot onto the intended body location. The design and fabrication of this soft robotic system are illustrated. To our knowledge, this is the first body-attached soft robot for compliant ultrasound imaging. The feasibility of the system is demonstrated through proof-of-concept experiments.

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Ultrasound Assisted Guidance with Force Cues for Intravascular Interventions

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Project Goals


Image guidance during minimally invasive cardiovascular interventions is primarily achieved based on X-ray fluoroscopy, which has several limitations including limited 3D imaging, significant doses of radiation to operators, and lack of contact force measurement between the cardiovascular anatomy and interventional tools. Ultrasound imaging may complement or possibly replace 2D fluoroscopy for intravascular interventions due to its portability, safety, and the ability of providing depth information. However, it is a challenging work to perfectly visualize catheters and guidewires in the ultrasound images. In this paper, we developed a novel method to locate the position and orientation of the catheter tip in 2D ultrasound images in real time by detecting and tracking a passive marker attached to the catheter tip. Moreover, the contact force can also be measured due to the length variation of the marker in real time. An active geometrical structure model based method was proposed to detect the initial position of the marker, and a KLT (Kanade-Lucas-Tomasi) based algorithm was developed to track the position, orientation, and the length of the marker. The ex vivo experimental results indicate that the proposed method is able to automatically locate the catheter tip in the ultrasound images and sense the contact force, so as to facilitate the operatorsโ€™ work during intravascular interventions.

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People Involved

Research Fellow: Jin Guo
Project Investigator: Hongliang Ren

Related Publications

TBA

Gold award in BES10SM Design Competition

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Congratulations to the Gold award in the Biomedical engineering Society 10th Scientific Meeting (BES10SM) at Singapore, 14th May 2016, for our lab’s research led by FYP student, Yoew Bok Seng, on the project of Magnetic Robotic Intervention, for the design (undergraduate) category.

Best Paper Finalist award at CSCWD 2016 Conference

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Our team’s research paper titled “Human-Compliant Body-Attached Soft Robots Towards Automatic Cooperative Ultrasound Imaging” paper was presented and shortlisted for the Best Conference Paper at 2016 20th IEEE International Conference on Computer Supported Cooperative Work in Design (CSCWD 2016), May 4-6, 2016, Nanchang, China.

Simultaneous Temperature Compensation and Synchronous Error Elimination for Axial Displacement Sensors Using an Auxiliary Probe

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Abstract

The output stability of the displacement sensors is an important issue for safe operations in magnetic bearing supported high-speed rotor system. This paper proposes an effective postprocessing solution to the problems of temperature drift and synchronous measuring error for the axial displacement sensor in a 10-kW magnetically suspended motor. The proposed configuration of the axial displacement sensor consists of three probes: one pair is used to eliminate the synchronous measuring error, and the third probe is employed for the consideration of temperature drift. First, the generating mechanism of the synchronous measuring error caused by the improper assemble is presented, and an operational amplifier is proposed to obtain an accurate position of the axial center by adjusting the weights of sensing signals from one pair of probes. Then the scheme of temperature compensation using an auxiliary probe is presented. In order to obtain accurately the characteristics of temperature drift at the operating point, the detailed procedure is given to determine the temperature-drift ratio. Finally, the terms related to temperature drift and synchronous error in the final output of the displacement sensor are both eliminated. Experimental results on a magnetically suspended motor test rig show the effectiveness of the proposed solution.

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Development of a compact continuum tubular robotic system for nasopharyngeal biopsy

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Abstract

Traditional posterior nasopharyngeal biopsy using a flexible nasal endoscope has the risks of abrasion and injury to the nasal mucosa and thus causing trauma to the patient. Recently, a new class of robots known as continuum tubular robots (CTRs) provide a novel solution to the challenge with miniaturized size, curvilinear maneuverability, and capability of avoiding collision within the nasal environment. This paper presents a compact CTR which is 35 cm in total length, 10 cm in diameter, 2.15 kg in weight, and easy to be integrated with a robotic arm to perform more complicated operations. Structural design, end-effector design, and workspace analysis are described in detail. In addition, teleoperation of the CTR using a haptic input device is developed for position control in 3D space. Moreover, by integrating the robot with three electromagnetic tracking sensors, a navigation system together with a shape reconstruction algorithm is developed. Comprehensive experiments are conducted to test the functionality of the proposed prototype; experiment results show that under teleoperation, the system has an accuracy of 2.20 mm in following a linear path, an accuracy of 2.01 mm in following a circular path, and a latency time of 0.1 s. It is also found that the proposed shape reconstruction algorithm has a mean error of around 1 mm along the length of the tubes. Besides, the feasibility and effectiveness of the proposed robotic system being applied to posterior nasopharyngeal biopsy are demonstrated by a cadaver experiment. The proposed robotic system holds promise to enhance clinical operation in transnasal procedures.

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Active Balancing Control of AMB-Rotor Systems Using a Phase-Shift Notch Filter Connected in Parallel Mode

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Abstract

The vibration controllability is an important feature in the applications of active magnetic bearings (AMBs). This paper addresses the two key challenges on the active balancing control of AMB-rotor systems: presenting a parallel-mode scheme to enhance the notch performance at high speeds, and proposing a phase-shift notch filter to ensure stable operations over the entire speed ranges. First, both the frequency characteristics of the simplified notch filter in series and in parallel mode are discussed. The analysis shows that the closed-loop system with a parallel-mode notch filter has a deeper notch depth and faster convergence. The capacities of the synchronous current elimination are also improved at high speeds. Then, an improved phase-shift notch filter connected in parallel with the controller is modeled and analyzed. In order to understand the sensibility of the proposed solution to phase-shift variations, the stability analysis of the closed-loop system in the entire operational speed range is performed using the frequency response method. Experimental results on a high-speed centrifugal air blower test rig show the effectiveness of the proposed solution.

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