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Modular robots can adapt to different production needs and working conditions. However, the complexity of structures and the choice of driving modes limit the development of modularization. In this paper, a robot joint module with a universal joint configuration driven by shape memory alloy (SMA) wires is proposed, which has 2-DOFs. For lightweight, the main body of the module is made of polylactic acid materials. SMA wires are used as the actuator due to the advantages of large output displacement, high mass-to-energy ratio, and low activation voltage. Adopting antagonistically arranged SMA wires and bias springs combination method increases the recovery speed and driving angles. A locking device is creatively proposed to avoid the influence of self-biasing spring compression. The detailed kinematic model of the module is established. A proportional integral differential controller is used to precisely control module movements, and the attitude angle sensor is used as the monitoring device. Through the maximum rotation angles and trajectory tracking movement experiments, the module is tested comprehensively, and the results show that the module has good movement characteristics and control precision. In addition, analyzing the tracking performance of the module in the time domain shows that the module has a relatively fast tracking speed. This module is beneficial to the research of configurations, actuators, and controls of modular robots. [ABSTRACT FROM AUTHOR]

Copyright of China Harbour Engineering is the property of Editorial Office of China Harbour Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ensure the safe operation of a mechanical system that involves motion is essential; some traditional ways to achieve this goal are mechanical devices such as breaks or clutches. This paper presents the design, manufacturing, and test of a bi-directional non-back-drivable mechanism for its application in miniature mechanical systems, like prostheses, robotics, or micro-machine tools. The bi-directional non-back-drivable mechanism operates as a locking device, limiting the torque transmission from the output into the input axle. Application of Design for X methods served to identified and prevent the main drawbacks of the mechanisms used for locking tasks, namely wear and backlash, to make the novel mechanism less sensitive to such factors, keeping high transmission performance in a tight space and with minimum parts. The presented set of design equations and selection graphs are for ABS plastic. A unified approach for the design of the bi-directional non-back-drivable mechanism is presented. The final section of the paper is devoted to the manufacturing and test of a sample of the mechanism. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The method of determining the optimal direction of satellite locking point is extended from the mechanical stability principle of plant roots growth under external loads. The method of topological optimization of the number and location of satellite locking units was proposed based on the adventitious root growth pattern of monocotyledons. Inspired by the fibrous root growth rhythm, the method for topological optimization of the effective contact interface shape of the satellite locking units is presented. A satellite finite element model and three-dimensional spring support model are established to lay the foundation for system frequency analysis. Parallel algorithm is used to optimize the position of the main locking points. One-dimensional search method is adopted to select the growth positions of the secondary locking points with the goal of maximizing fundamental frequency of the system. The relationship between the locking stiffness and system fundamental frequency is explored. Finally, the optimization results of this method are compared with those of conventional methods; the comparison demonstrated that the fundamental frequency of the locking system is significantly enhanced by the proposed method. [ABSTRACT FROM AUTHOR]

Lynchburg Nephrology Dialysis Incorporated started its nightly home hemodialysis (NHHD) program in September 1997.The purpose of this study was to evaluate episodes of exit-site infections, catheter sepsis, and safety and longevity of accesses for patients doing NHHD.If internal jugular (IJ) catheter was chosen, the patient was started on 2 mg coumadin per day when catheter was placed. If catheter malfunctioned, it was blocked with a thrombolytic agent and coumadin was adjusted to meet a goal international normalized ratio (INR) of 1.5 to 2.25. If the problem persisted, the catheter was exchanged. For catheters, a threaded lock cannula (BD InterLink device, BD) was used to prevent air emboli and infections and a locking device was used to prevent disconnects. If arteriovenous (AV) fistula was used, four buttonholes were established using 16-gauge needles. If AV graft was used, patients were taught the rope ladder cannulation technique using 16-gauge needles.As of September 1, 2003, 45 patients have completed training and have performed 27,063 treatments at home. Total catheter time at home was 930 months. Total AV fistula and AV graft times at home were 190 and 20 months, respectively. Upon completion of training, 34 patients were using tunneled IJ catheters, 10 were using AV fistulas, and 1 was using an AV graft. The IJ catheter exit-site and sepsis infection rates were 0.35 and 0.52 episodes per 1000 patient-days, respectively. Mean catheter life was 8.5 months with the longest being 66.7 months and the shortest being 0.2 months. The AV fistula and graft exit-site and sepsis infection rates were 0.16 and 0 episodes per 1000 patient-days, respectively. Catheter complications included one episode of disconnect due to patient's failure to use the locking device, one episode of central stenosis, and one episode of intracranial hemorrhage, due to prolonged INR, with resolution of symptoms.Data support the fact that tunneled IJ catheters, AV fistulas, and AV grafts are effective and safe permanent accesses for patients on NHHD. [ABSTRACT FROM AUTHOR]