Robotic technologies are being employed increasingly in the treatment of lower limb disabilities. Individuals suffering from stroke and other neurological disorders often experience inadequate dorsiflexion during swing phase of the gait cycle due to dorsiflexor muscle weakness. This type of pathological gait, mostly known as drop-foot gait, has two major complications, foot-slap during loading response and toe-drag during swing. Ankle foot orthotic (AFO) devices are mostly prescribed to resolve these complications. Existing AFOs are designed with or without articulated joint with various motion control elements like springs, dampers, four-bar mechanism, series elastic actuator, and so forth. This paper examines various AFO designs for drop-foot, discusses the mechanism, and identifies limitations and remaining design challenges. Along with two commercially available AFOs some designs possess promising prospective to be used as daily-wear device. However, the design and mechanism of AFO must ensure compactness, light weight, low noise, and high efficiency. These entailments present significant engineering challenges to develop a new design with wide consumer adoption.
High-efficiency inductive power transfer (IPT) with low misalignment effects is a key issue in the dynamic charging of electric vehicle (EV) systems. In this study, an advanced concept of analysis and design of transmitter and receiver coils with a special coil assembly is proposed for the dynamic charging of EVs. In each transmitter coil, large rectangular section is series connected with two zigzag-shaped small rectangular sections. These small sections are back-to-back series connected and located inside the large rectangular section. An adjacent pair of proposed transmitter coils with back-to-back series connection named extended double D (DD)-shaped transmitter is used throughout this paper. The major contribution in the case of the extended DD transmitter is negligible power transfer fluctuation, regardless of any horizontal misalignment of the receiver coil. Justification of the coil design is performed based on its load independent voltage gain and power transfer fluctuation characteristics. Experimental results prove that the power transfer fluctuation with load independent voltage gain is within ±6%, and the efficiency is approximately 93% under horizontal misalignment of receiver coil with an air gap of 140 mm. Finally, a new coil design set with a special arrangement has been proposed to maintain nearly uniform coupling factor and negligible power transfer fluctuation.
While the Smart Grid Demo was completed by the end of January 2015, PGE has continued using this facility in a manner consistent with the original purpose of the program. PNNL was engaged by DOE and PGE to review SSPC operations and to evaluate its technical performance and financial potential. This report presents the results of the PNNL performance tests and the efforts to co-optimize a bundle of SSPC energy storage use cases to enhance its economic value to PGE and the customers it serves. The following key lessons and implications can be drawn from the analysis. 1-The SSPC is Currently Underutilized and Optimal Operation Could Generate an Additional $170,000 in Value Annually In terms of economic operation, the SSPC is currently underutilized, operating an average of 14 hours per month, or 1.9 percent of available hours. With that noted, PGE is using the BESS for the highest value application (primary frequency response
Traditional design and manufacturing methods of ankle foot orthosis (AFO) involve manual techniques e.g., casting and molding of the limbs and often depend on trial and error. Three-dimensional scanning allows computer aided design (CAD) tools to be incorporated, however, both approaches rely on the external model of the limb. To design AFO with articulated joint, precise alignment of mechanical and anatomical joint axes is imperative. It is difficult to infer joint axis from external model as it is partially specified by the skeletal structure. In this article, a computer integrated design approach of an articulated AFO has been demonstrated. CAD model of the AFO was developed for a healthy subject's left leg based on the 3D models of skeleton and soft tissue of the limb. Components of the AFO were fabricated by rapid prototyping and CNC machining. The design approach is faster than the traditional techniques and also facilitates exact positioning of articulated ankle joint. The gait analysis indicates that the subject's ankle had to overcome lesser resistance with the custom made AFO compared to a pre-fabricated AFO. Simultaneous viewing of exterior and skeletal geometry might help the clinicians modify the design to enhance performance of the orthotic.
A novel LC-LC2 compensated resonant converter topology with high efficiency and good controllable voltage gain is presented in this paper. An additional receiving side inductor working together with the receiving coil has the contribution to work with a large range of air gap distance. Due to this property, proposed compensation technique is effective for IPT based EV charging application. Voltage gain with independent of load and input impedance having ZPA of the proposed resonant converter are observed by the frequency domain analysis. On the other hand, time domain analysis gives the circuit operation. A 500 W LC-LC2 compensated resonant converter prototype is built to testify the theoretical analysis. To observe the efficiency-comparison, an S-SP compensated resonant converter with a similar amount of output power under different air gap is also presented. In order to justify the effectiveness, the proposed compensation method is verified by the laboratory results. The highest efficiency of the proposed compensated resonant converter is 93% with output power of 500 W at 140-mm air gap between the two sides of the IPT (inductive power transfer) transformer.
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