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Kinematics & Dynamics Library for Baxter Arm

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arXiv 2024年

作者： Kumar, Akshay Sahasrabudhe, Ashwin Perugu, Chaitanya Nirgude, Sanjuksha Murugan, Aakash Department of Robotics Engineering Worcester Polytechnic Institute United States

The Baxter robot is a standard research platform used widely in research tasks, supported with an SDK provided by the developers, Rethink robotics. Despite the ubiquitous use of the robot, the official software support is sub-standard. Especially, the native IK service has a low success rate and is often inconsistent. This unreliable behavior makes Baxter difficult to use for experiments and the research community is in need of a more reliable software support to control the robot. We present our work towards creating a Python based software library supporting the kinematics and dynamics of the Baxter robot. Our toolbox contains implementation of pose and velocity kinematics with support for Jacobian operations for redundancy resolution. We present the implementation and performance of our library, along with a comparison with PyKDL. © 2024, CC0.

关键词： Redundant manipulators

Feasibility of Pointcloud-based Ultrasound-CT Registration towards Automated, Robot-Assisted Image-Guidance in Spine Surgery*

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Feasibility of Pointcloud-based Ultrasound-CT Registration t...

International Symposium on Medical robotics (ISMR)

作者： Xihan Ma Xiao Zhang Yang Wang Christopher Nycz Arno Sungarian Songbai Ji Haichong K. Zhang Department of Robotics Engineering Worcester Polytechnic Institute Worcester MA USA Department of Electrical and Computer Engineering Worcester Polytechnic Institute Worcester MA USA University of Massachusetts Memorial Medical Center Worcester MA USA Department of Biomedical Engineering Worcester Polytechnic Institute Worcester MA USA Department of Biomedical Engineering and the Department of Robotics Engineering Worcester Polytechnic Institute Worcester MA USA

ISBN: (数字)9798350377118

ISBN: (纸本)9798350377125

Image-guidance has been shown to improve spine surgical accuracy and patient outcome. Such image guidance can be achieved by registering low-cost, realtime, and radiation-free intraoperative ultrasound (US) with preoperative computed tomography (CT). Employing robotic US system (RUSS) allows automated acquisition of a wide 3D volume, facilitating efficient and accurate registration with CT. However, the registration between CT and robotic 3D US remains an open problem mainly due to (i) the lack of relevant testbed and dataset, and (ii) the modality discrepancy between CT and US. To address these challenges, we present a custom-built lumbar spine phantom for multimodal imaging with rigidly attached fiducials. The phantom is scanned by CT and in-house RUSS. A novel pointcloud-based registration pipeline is presented to register CT and robotic 3D US data of the spine phantom. Preliminary experiments demonstrate efficient (0.53 ± 0.02 seconds) registration of the lumbar spine with an accuracy of 3.57 mm in terms of fiducial registration error (FRE), which is robust to varying initial alignment of the pointclouds. These results show initial feasibility of adopting the proposed registration pipeline in robotic US guided spine surgery. Future work includes further evaluation of registration performance in ex vivo spine samples with denser US acquisitions to further improve registration accuracy.

关键词： Accuracy Three-dimensional displays Ultrasonic imaging Medical robotics Computed tomography Spine Pipelines

programmable Switching of Fluids via Pre-Twisting

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Programmable Switching of Fluids via Pre-Twisting

IEEE International Conference on Soft robotics (RoboSoft)

作者： Yijia Wu Markus P. Nemitz Department of Robotics Engineering Worcester Polytechnic Institute Worcester MA USA Department of Mechanical and Materials Engineering Worcester Polytechnic Institute Worcester MA USA Department of Electrical and Computer Engineering Worcester Polytechnic Institute Worcester MA USA

Manipulating airflow is important for controlling pneumatically actuated soft robots, however, current switching techniques suffer from leakage under high pressure ( $> 200$ kPa) or require a complex fabrication process. We propose a new method for reliably and repeatably cutting off airflow by harnessing pre-loaded torsional forces applied to our tubing. The switching distance and hysteresis of our pre-twisted tubing are programmable by varying the tube length and the twisting angle. Our experiments demonstrate the use of pre-twisted tubing to implement CMOS equivalent fluidic switches configured as NOT-, AND-, and OR-gates, and a distance sensor for feedback control for the oscillation of a PneuNet. Our approach of pre-loading tubes with a torsional force allows for simplicity, integrated functionality, and the capability of manipulating high-pressure, fluidic signals mainly at the cost of tubing.

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SURF-COM: An Open Source Acoustic Controller for Soft Underwater Robots

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SURF-COM: An Open Source Acoustic Controller for Soft Underw...

IEEE International Conference on Soft robotics (RoboSoft)

作者： Natalie Essig Brighton Lee Robin Hall Cagdas D. Onal WPI Soft Robotics Laboratory Robotics Engineering Department Worcester Polytechnic Institute MA USA

ISBN: (数字)9798331520205

ISBN: (纸本)9798331520212

Underwater untethered communication tends to require expensive, heavy, large, or complicated custom solutions. For soft underwater robots, we need a small, light, inexpensive, and reliable framework to send commands, especially when going into delicate underwater environments where a diver operator may need to keep a distance. This paper introduces SURF-COM (Simple Underwater Robotic Framework for Communication), an open-source acoustic controller for underwater robots. Made from entirely off-the-shelf components, this controller can easily be integrated into any underwater robot and was tested here on a soft vectored underwater vehicle (VUV). The controller uses basic frequencies to signal different commands for the robot, controlling its direction and speed. It has a maximum tested range (lateral distance between transmitter and receiver) of 45 m and can operate at up to 5 m in depth (distance of both transmitter and receiver from the surface of the water). It has a response time of 0.167 s. The controller is compact and packaged into a user-friendly, intuitive interface. We operated the robot, untethered, in various environments to test the robustness of the controller and analyze its performance.

关键词： Autonomous underwater vehicles Sea surface Transmitters Receivers Soft robotics Reliability engineering Acoustics Robustness Time factors Testing

A Starter’s Kit for Concentric Tube Robots

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arXiv 2024年

作者： Bonofiglio, Kalina Wang, Wenpeng Wilke, Ethan R. Rajaraman, Adri Fichera, Loris The Department of Robotics Engineering Worcester Polytechnic Institute WorcesterMA01609 United States

Concentric Tube Robots (CTRs) have garnered significant interest within the surgical robotics community because of their flexibility, dexterity, and ease of miniaturization. However, mastering the unique kinematics and design principles of CTRs can be challenging for newcomers to the field. In this paper, we present an educational kit aimed at lowering the barriers to entry into concentric tube robot research. Our goal is to provide accessible learning resources for CTRs, bridging the knowledge gap between traditional robotic arms and these specialized devices. The proposed kit includes (1) An open-source design and assembly instructions for an economical (cost of materials ≈ 700 USD) modular CTR;(2) A set of self-study materials to learn the basics of CTR modeling and control, including automatically-graded assignments. To evaluate the effectiveness of our educational kit, we conducted a human subjects study involving first-year graduate students in engineering. Over a four-week period, participants — none of whom had any prior knowledge of concentric tube robots — successfully built their first CTR using the provided materials, implemented the robot’s kinematics in MATLAB, and conducted a tip-tracking experiment with an optical tracking device. Our findings suggest that the proposed kit facilitates learning and hands-on experience with CTRs, and furthermore, it has the potential to help early-stage graduate students get rapidly started with CTR research. By disseminating these resources, we hope to broaden participation in concentric tube robot research to a wider a more diverse group of researchers. Copyright © 2024, The Authors. All rights reserved.

关键词： Kinematics

Towards a Physics Engine to Simulate Robotic Laser Surgery: Finite Element Modeling of Thermal Laser-Tissue Interactions

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arXiv 2024年

作者： Pacheco, Nicholas E. Zhang, Kang Reyes, Ashley S. Pacheco, Christopher J. Burstein, Lucas Fichera, Loris The Department of Robotics Engineering Worcester Polytechnic Institute WorcesterMA01690 United States

This paper presents a computational model, based on the Finite Element Method (FEM), that simulates the thermal response of laser-irradiated tissue. This model addresses a gap in the current ecosystem of surgical robot simulators, which generally lack support for lasers and other energy-based end effectors. In the proposed model, the thermal dynamics of the tissue are calculated as the solution to a heat conduction problem with appropriate boundary conditions. The FEM formulation allows the model to capture complex phenomena, such as convection, which is crucial for creating realistic simulations. The accuracy of the model was verified via benchtop laser-tissue interaction experiments using agar tissue phantoms and ex-vivo chicken muscle. The results revealed an average root-mean-square error (RMSE) of less than 2 ◦C across most experimental conditions. Copyright © 2024, The Authors. All rights reserved.

关键词： Heat conduction

Design and Characterization of MRI-compatible Plastic Ultrasonic Motor

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arXiv 2024年

作者： Zhao, Zhanyue Bales, Charles Fischer, Gregory The Department of Robotics Engineering Worcester Polytechnic Institute WorcesterMA01605 United States

Precise surgical procedures may benefit from intraoperative image guidance using magnetic resonance imaging (MRI). However, the MRI’s strong magnetic fields, fast switching gradients, and constrained space pose the need for an MR-guided robotic system to assist the surgeon. Piezoelectric actuators can be used in an MRI environment by utilizing the inverse piezoelectric effect for different application purposes. Piezoelectric ultrasonic motor (USM) is one type of MRI-compatible actuator that can actuate these robots with fast response times, compactness, and simple configuration. Although the piezoelectric motors are mostly made of nonferromagnetic material, the generation of eddy currents due to the MRI’s gradient fields can lead to magnetic field distortions causing image artifacts. Motor vibrations due to interactions between the MRI’s magnetic fields and those generated by the eddy currents can further degrade image quality by causing image artifacts. In this work, a plastic piezoelectric ultrasonic (USM) motor with more degree of MRI compatibility was developed and induced with preliminary optimization. Multiple parameters, namely teeth number, notch size, edge bevel or straight, and surface finish level parameters were used versus the prepressure for the experiment, and the results suggested that using 48 teeth, thin teeth notch with 0.39mm, beveled edge and a surface finish using grit number of approximate 1000 sandpaper performed a better output both in rotary speed and torque. Under this combination, the highest speed reached up to 436.6665rpm when the prepressure was low, and the highest torque reached up to 0.0348Nm when the prepressure was approximately 500g. © 2024, CC BY-NC-SA.

关键词： Piezoelectric motors

Development of Advanced FEM Simulation Technology for Pre-Operative Surgical Planning

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arXiv 2024年

作者： Zhao, Zhanyue Jiang, Yiwei Bales, Charles Wang, Yang Fischer, Gregory The Department of Robotics Engineering Worcester Polytechnic Institute WorcesterMA01605 United States

Intracorporeal needle-based therapeutic ultrasound (NBTU) offers a minimally invasive approach for the thermal ablation of malignant brain tumors, including both primary and metastatic cancers. NBTU utilizes a high-frequency alternating electric field to excite a piezoelectric transducer, generating acoustic waves that cause localized heating and tumor cell ablation, and it provides a more precise ablation by delivering lower acoustic power doses directly to targeted tumors while sparing surrounding healthy tissue. Building on our previous work, this study introduces a database for optimizing preoperative surgical planning by simulating ablation effects in varied tissue environments and develops an extended simulation model incorporating various tumor types and sizes to evaluate thermal damage under trans-tissue conditions. A comprehensive database is created from these simulations, detailing critical parameters such as CEM43 isodose maps, temperature changes, thermal dose areas, and maximum ablation distances for four directional probes. This database serves as a valuable resource for future studies, aiding in complex trajectory planning and parameter optimization for NBTU procedures. Moreover, a novel probe selection method is proposed to enhance pre-surgical planning, providing a strategic approach to selecting probes that maximize therapeutic efficiency and minimize ablation time. By avoiding unnecessary thermal propagation and optimizing probe angles, this method has the potential to improve patient outcomes and streamline surgical procedures. Overall, the findings of this study contribute significantly to the field of NBTU, offering a robust framework for enhancing treatment precision and efficacy in clinical settings. © 2024, CC BY-NC-SA.

关键词： Ablation

A Preliminary Add-on Differential Drive System for MRI-Compatible Prostate Robotic System

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arXiv 2024年

作者： Zhao, Zhanyue Jiang, Yiwei Bales, Charles Wang, Yang Fischer, Gregory The Department of Robotics Engineering Worcester Polytechnic Institute WorcesterMA01605 United States

MRI-targeted biopsy has shown significant advantages over conventional random sextant biopsy, detecting more clinically significant cancers and improving risk stratification. However, needle targeting accuracy, especially in transperineal MRI-guided biopsies, presents a challenge due to needle deflection. This can negatively impact patient outcomes, leading to repeated sampling and inaccurate diagnoses if cancerous tissue isn't properly collected. To address this, we developed a novel differential drive prototype designed to improve needle control and targeting precision. This system, featuring a 2-degree-of-freedom (2-DOF) MRI-compatible cooperative needle driver, distances the robot from the MRI imaging area, minimizing image artifacts and distortions. By using two motors for simultaneous needle insertion and rotation without relative movement, the design reduces MRI interference. In this work, we introduced two mechanical differential drive designs: the ball screw/spline and lead screw/bushing types, and explored both hollow-type and side-pulley differentials. Validation through low-resolution rapid-prototyping demonstrated the feasibility of differential drives in prostate biopsies, with the custom hollow-type hybrid ultrasonic motor (USM) achieving a rotary speed of 75 rpm. The side-pulley differential further increased the speed to 168 rpm, ideal for needle rotation applications. Accuracy assessments showed minimal errors in both insertion and rotation motions, indicating that this proof-of-concept design holds great promise for further development. Ultimately, the differential drive offers a promising solution to the critical issue of needle targeting accuracy in MRI-guided prostate biopsies. © 2024, CC BY-NC-SA.

关键词： Ball screws