- 标题
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- 实验方案
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Closed-loop functional optogenetic stimulation
摘要： Optogenetics has been used to orchestrate temporal- and tissue-specific control of neural tissues and offers a wealth of unique advantages for neuromuscular control. Here, we establish a closed-loop functional optogenetic stimulation (CL-FOS) system to control ankle joint position in murine models. Using the measurement of either joint angle or fascicle length as a feedback signal, we compare the controllability of CL-FOS to closed-loop functional electrical stimulation (CL-FES) and demonstrate significantly greater accuracy, lower rise times and lower overshoot percentages. We demonstrate orderly recruitment of motor units and reduced fatigue when performing cyclical movements with CL-FOS compared with CL-FES. We develop and investigate a 3-phase, photo-kinetic model to elucidate the underlying mechanisms for temporal variations in optogenetically activated neuromusculature during closed-loop control experiments. Methods and insights from this study lay the groundwork for the development of closed-loop optogenetic neuromuscular stimulation therapies and devices for peripheral limb control.
关键词： Functional stimulation,Photo-kinetic model,Motor units,Optogenetics,Neuromuscular control,Fatigue,Closed-loop control
更新于2025-09-23 15:23:52
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Closed Loop Control of a Series Class-E Voltage-Clamped Resonant Converter for LED Supply with Dimming Capability
摘要： In this work, a new closed-loop control system is applied to a class-E resonant DC–DC converter with voltage clamp used for light-emitting diode (LED) supply. The proposed power topology was first described by Ribas et al. in a recent work. In the present paper, the LED current is sensed and used to implement a feedback control loop instead of the simplified feedforward scheme used in this previous reference. To design the control, a novel, simplified small-signal model is presented. This model is used to analyze the converter behavior as a function of the output power. The proposed approximation is significantly simpler than the multifrequency averaging technique normally used to analyze resonant converters. The feedback control loop is designed to reduce the LED low frequency current ripple while providing dimming control. Both the model and the control are verified by simulation and laboratory experimentation and the results obtained are in good accordance with the expected values.
关键词： small-signal dynamic model,light-emitting diode (LED) driver,high efficiency LEDs,resonant DC–DC converter,Class-E inverter,single-switch topology,closed-loop control,voltage clamp
更新于2025-09-23 15:19:57
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[IEEE 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - Brasov, Romania (2019.11.3-2019.11.6)] 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - The Closed Loop Controller Gain Characterization for Enhanced Current Quality in Solar Inverters Coupled with Weak Grid
摘要： Majority of solar installations are coming up in remote locations where the stiffness of the grid is very weak, enforces to connect solar inverters to weak grid. In weak grid scenario, solar inverter would inject harmonic current into the grid that affect the power quality of the system. The solar inverters are designed to operate with stiff grid in which the closed (feedback and feed forward) loop control is planned by considering absolute decoupling between the direct and quadrature grid injected current. With the conventional design speci?cations in weak grid scenario, the absolute decoupling between the direct and quadrature current cannot be achieved due to grid inductance. The improper decoupling would create the oscillations in the grid injected current that result in increased harmonic distortion. To compensate the current oscillations, the current controller feedback loop gain need to be designed by accessing the degree of coupling. Since the grid injected current sensed at the point of common coupling and transformed to DC quantities (direct current id and quadrature current iq) using synchronous angle, the same current oscillations appear in d-axis and q-axis current control loop. In this work, the d-axis and q-axis loop oscillations with respect to grid inductance are analyzed analytically. Based on the analysis the d-axis and q-axis PI controllers are designed independently unlike conventional PI controller to ensure not only faster dynamic response of the system but also improved power quality.
关键词： closed loop control,weak grid,PI controllers,current THD,Grid connected solar inverter,single stage transformer less grid connected inverter,Power quality
更新于2025-09-23 15:19:57
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Parallel in-situ measurement of heliostat aim points in central receiver systems by image processing methods
摘要： Central Receiver Systems use thousands of heliostats distributed in a field to reflect the solar radiation to a receiver installed at a tower. The large distances between the heliostats and their aim point require a high precision of the heliostat control and drive system to efficiently concentrate the solar radiation and to allow for a safe and reliable plant operation. Precise calibration procedures are needed for the commissioning of open loop systems. Furthermore, the need for cost reduction in the heliostat field motivates for precise and fast calibration systems allowing for savings in the design of the individual heliostats. This work introduces a method for the measurement of true aim points of heliostats in operation. A proposed application is the plug-in system HelioControl, to be used for parallel in-situ calibration of multiple heliostats in operation. The approach aims at extracting the focal spot position of individual heliostats on the receiver domain using image analysis and signal modulation. A centralized remote vision system, installed far from the harsh conditions at the focal area, takes image sequences of the receiver domain. During the measurement, a signal is modulated on different heliostats which is then extracted for the retrieval of the true aim points. This paper describes the theoretical background of the methodology and demonstrates the functionality based on two simulated cases showing the practical advantages introduced with this approach.
关键词： Heliostat field calibration,Heliostat tracking,Closed-loop control,Central receiver systems
更新于2025-09-19 17:15:36
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Beyond the Toolpath: Site-Specific Melt Pool Size Control Enables Printing of Extra-Toolpath Geometry in Laser Wire-Based Directed Energy Deposition
摘要： A variety of techniques have been utilized in metal additive manufacturing (AM) for melt pool size management, including modeling and feed-forward approaches. In a few cases, closed-loop control has been demonstrated. In this research, closed-loop melt pool size control for large-scale, laser wire-based directed energy deposition is demonstrated with a novel modification, i.e., site-specific changes to the controller setpoint were commanded at trigger points, the locations of which were generated by the projection of a secondary geometry onto the primary three-dimensional (3D) printed component geometry. The present work shows that, through this technique, it is possible to print a specific geometry that occurs beyond the actual toolpath of the print head. This is denoted as extra-toolpath geometry and is fundamentally different from other methods of generating component features in metal AM. A proof-of-principle experiment is presented in which a complex oak leaf geometry was embossed on an otherwise ordinary double-bead wall made from Ti-6Al-4V. The process is introduced and characterized primarily from a controls perspective with reports on the performance of the control system, the melt pool size response, and the resulting geometry. The implications of this capability, which extend beyond localized control of bead geometry to the potential mitigations of defects and functional grading of component properties, are discussed.
关键词： closed-loop control,lasers,metal,directed energy deposition,additive manufacturing,3D printing,titanium,site-specific,melt pool size
更新于2025-09-19 17:13:59
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Design of a MEMS-Mirror-based Laser Pointing Control System of Optical Transponder for Micro-satellites
摘要： Optical communication technologies are regarded as an important breakthrough for future satellite communications. Tohoku University has been developing Adjustable beam angle Small Optical TrAnsponder (ASOTA) for micro-satellites. The design concept of ASOTA is miniaturization and low power consumption. It is necessary for space optical communication to direct the laser to the ground station with a high precision. This research describes the development of a MEMS-Mirror-based Fine Pointing Mechanism (FPM). The MEMS mirror is suitable for micro-satellites because it is smaller and consumes less power than 2-axis gimbal mechanisms. FPM is a feedback control system consisting of a MEMS mirror and a Quadrant Detector. The characteristics and mathematical model of each device are described. Then numerical simulation and ground evaluation results of FPM with a simple optical system are summarized.
关键词： Optical Communication,Laser Tracking,MEMS Mirror,Closed Loop Control,Micro-satellite
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Seoul, Korea (South) (2019.1.27-2019.1.31)] 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - A Closed-Loop Controlled Cmos Mems Biaxial Scanning Mirror for Projection Display
摘要： This work presents a bi-axial electromagnetically-driven piezoresistively sensed scanning mirror with a θopt?D?fr,fast product over 2400 deg?mm?kHz, showing the capability to achieve HD720 (720 × 1280) display resolution. Both driving and sensing capabilities are conveniently realized by CMOS MEMS technologies. The transduction mechanism provides a more linear response than capacitively transduced scanning mirrors. Based on the open-loop characterization of the driving and sensing performance, closed-loop control of slow-axis motion is designed and demonstrated.
关键词： piezoresistive sensing,closed-loop control,scanning mirror,CMOS MEMS,electromagnetic actuation,projection display
更新于2025-09-12 10:27:22
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A Reconfigurable Solar Photovoltaic Grid-Tied Inverter Architecture for Enhanced Energy Access in Backup Power Applications
摘要： In this paper, a photovoltaic (PV) reconfigurable grid-tied inverter (RGTI) scheme is proposed. Unlike a conventional GTI that ceases operation during a power outage, the RGTI is designed to act as a regular GTI in the on-grid mode but it is reconfigured to function as a DC-DC charge-controller that continues operation during a grid outage. During this period, the RGTI is tied to the battery-bank of an external UPS based backup power system to augment it with solar power. Such an operation in off-grid mode without employing high-bandwidth communication with the UPS is challenging, as the RGTI control must not conflict with the battery management system of the UPS. The hardware and control design aspects of this requirement are discussed in this paper. A battery emulation control scheme is proposed for the RGTI that facilitates seamless functioning of the RGTI in parallel with the physical UPS battery to reduce its discharge current. A system-level control scheme for overall operation and power management is presented to handle the dynamic variations in solar irradiation and UPS loads during the day, such that the battery discharge burden is minimized. The design and operation of the proposed RGTI system are independent of the external UPS and can be integrated with an UPS supplied by any manufacturer. Experimental results on a 4 kVA hardware setup validate the proposed RGTI concept, its operation and control.
关键词： Solar PV,Battery,Grid-tied Inverters,dual-mode inverters,UPS,Closed-loop control
更新于2025-09-12 10:27:22
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Design and Fabrication of a Three-dimensional Meso-sized Robotic Metamaterial with Actively Controlled Properties
摘要： This work introduces a robotic metamaterial that consists of meso-sized compliant cells that interact with each other using embedded actuators and sensors to achieve desired system-level properties via active closed-loop control. Each cell possesses a microprocessor at its core that can receive uploaded control instructions, which dictate how the cell responds to the loads and relative displacements of neighboring cells. Using this swarm control approach, desired bulk properties emerge from the metamaterial in response to external loads regardless of how the cells are arranged within the material’s lattice. Such materials can achieve unprecedented properties and combinations of properties that are not possible to achieve using natural homogenous materials, composites, or even passive architected materials. Additionally, these properties can be adjusted on demand as rapidly as new instructions can be uploaded to the microprocessors within their lattices. Although, in theory, such materials could be used to satisfy the property requirements of almost any application, they are difficult to fabricate, particularly with cells small enough to be considered a material rather than a collection of macro-sized robots. Here we introduce the first three-dimensional property-controlled robotic metamaterial ever fabricated. Its cells are 5 mm in size and successfully achieve properties via closed-loop control.
关键词： 3D fabrication,closed-loop control,robotic metamaterial,active control,meso-sized cells
更新于2025-09-11 14:15:04