Open-loop Control Research Articles

Implementation of unidirectional control mechanism for DC-DC converters

In the ongoing global transition from non-renewable energy sources to renewables such as solar, wind, and tidal power, solar energy plays a predominant role. Take, for instance, the widespread use of solar-powered e-rickshaws. These vehicles require a consistent and lowharmonics DC supply to charge their batteries. However, during overcast days, the solar panels on the e-rickshaws may struggle to provide the necessary power for battery charging, leading to potential interruptions. One effective solution to address this challenge involves implementing a DC-DC converter to maintain a stable voltage supply to the load. Three types of DC converters have been designed and their input-output voltage relations are calculated and compared. All three converters are simulated using MATLAB with an open-loop control approach.

Mechanical intelligence simplifies control in terrestrial limbless locomotion.

Limbless locomotors, from microscopic worms to macroscopic snakes, traverse complex, heterogeneous natural environments typically using undulatory body wave propagation. Theoretical and robophysical models typically emphasize body kinematics and active neural/electronic control. However, we contend that because such approaches often neglect the role of passive, mechanically controlled processes (those involving "mechanical intelligence"), they fail to reproduce the performance of even the simplest organisms. To uncover principles of how mechanical intelligence aids limbless locomotion in heterogeneous terradynamic regimes, here we conduct a comparative study of locomotion in a model of heterogeneous terrain (lattices of rigid posts). We used a model biological system, the highly studied nematode worm Caenorhabditis elegans, and a robophysical device whose bilateral actuator morphology models that of limbless organisms across scales. The robot's kinematics quantitatively reproduced the performance of the nematodes with purely open-loop control; mechanical intelligence simplified control of obstacle navigation and exploitation by reducing the need for active sensing and feedback. An active behavior observed in C. elegans, undulatory wave reversal upon head collisions, robustified locomotion via exploitation of the systems' mechanical intelligence. Our study provides insights into how neurally simple limbless organisms like nematodes can leverage mechanical intelligence via appropriately tuned bilateral actuation to locomote in complex environments. These principles likely apply to neurally more sophisticated organisms and also provide a design and control paradigm for limbless robots for applications like search and rescue and planetary exploration.

Design and Cryogenic Performance of a Hexapod Platform for a Large Ground-based Wide Field Survey Telescope

The thermal gradient is an important factor that causes degradation to the image quality of telescopes. In order to ensure the accurate alignment of the primary focus unit and the primary mirror, the hexapod platform (as a corrector) is investigated in this paper. First, a ground-based telescope with 2.5 m aperture and 3.5 deg field of view is described. The telescope is under construction, and it is expected to be finished in 2023. Second, the hexapod platform with flexure hinges utilized to adjust the primary focus unit is proposed, which is applied as a corrector. Then, the inverse kinematics of the platform is established and an open-loop control system is built based on it. Finally, the cryogenic performance test for the hexapod platform is performed. The experimental results show that the resolution and repeatability of the translation for the hexapod platform can be achieved at the micrometer level. The resolution and repeatability of the rotation can be achieved at the arc-second level. Therefore, the cryogenic performance of the hexapod platform can meet the optical imaging requirements of the wide-field ground-based telescope. The kinematic analysis and cryogenic performance tests in the paper provide a technical reference for the precise alignment of the primary focus unit and the primary mirror, which can improve the imaging quality of the telescope.

A 4 mm Micro Servo Control System in Fiber Positioner

As multi-object spectrographs (MOSs) continue to evolve, a notable trend has emerged—the increasing accommodation of fiber positioners on ever-more compact focal planes. This progression has seen the traditional stepper motors being supplanted by more space-efficient miniature hollow-cup motors. A significant challenge faced in the employment of these 4 mm diameter motors is the absence of compatible angle sensors, resulting in reliance on open-loop control methods for positioning. Addressing this challenge, this paper introduces a novel miniature angle sensor designed specifically for 4 mm hollow-cup motors, and presents a newly formulated closed-loop control scheme, which leverages this sensor to achieve accurate positioning. This marks the first implementation of an angle closed-loop control system within a 4 mm miniature hollow-cup motor used in MOS fiber positioners. Experimental evidence suggests that this sensored closed-loop mode substantially improves upon the energy efficiency and precision of fiber positioner placement, compared with traditional open-loop stepper control methods. Furthermore, the integration of these microsensors mitigates collision risks during the concurrent operation of fiber positioners by deactivating the motor power supply to prevent potential damage to the system.

Closed-Loop Control and Plant Co-Design of a Hybrid Electric Unmanned Air Vehicle

Abstract Novel conceptual aircraft designs have been enabled by more electrified aircraft components providing enhanced capability and versatility. Through the advancement of multidisciplinary design optimization, control co-design methods have become a popular approach for system design conceptualization wherein the plant and control actions are designed simultaneously to account for the coupling between vehicle subsystems and power management systems. Many prior efforts have focused on open-loop control co-design that can later be adapted for a more realistic operating case. This work focuses on the development and scalability of closed-loop control co-design that would result in a physically realizable plant and closed-loop control law. The theoretical approach is demonstrated practically through the design of a hybrid electric unmanned air vehicle and two feedback controllers that operate the hybrid power split and propulsion system. The system is designed to complete a dynamic seven phase mission consisting of multiple cruise, dash, engage, dive, and climb segments as quickly as possible. Given the scale of the dynamic design problem, a convergence study is introduced that facilitates accurate and computationally tractable design optimization studies. The study is conducted for independent, sequential, and simultaneous design approaches. The results indicate high-speed motors, high voltage batteries, and responsive control gains result in a fast vehicle with high thrust-to-weight ratio. The simultaneous design solution had the best closed-loop performance, outclassing a baseline system design by over 30%.

Cyclic Impact Test with the Hopkinson Bar: Application to Granite

A laboratory scale cyclic impact loading test was developed by modifying a Hopkinson Bar test setup. The modifications involve placing a special shank piece between the striker and the rest of the setup. The shank transmits the impact loading and enables the use of compressed air for rapid reloading of the striker. The short shank is in direct contact with the specimen, i.e., there is no long input bar. With this configuration residual wave motion and reloading of the specimen is avoided. Behind the striker an output bar and momentum trap bar are placed for specimen loading measurement and removal of the wave motion in the system, respectively. The trap bar is stopped by a pneumatic actuator, which also resets the bars and the specimen before the next impact loading. The compressed air flow driving the striker is controlled by high-speed electropneumatic valves connected to a control unit and operated in simple open-loop control. Numerical simulations of both the striker motion by compressed air and dynamic loading wave propagation during impact were used in the design phase as well as setting up the test parameters. The test setup is able to produce stable cyclic impact loading at a frequency of up to 10 impacts per second with striker velocity up to 9 m/s. The feasibility of the test method is demonstrated by providing data from cyclic Brazilian disc experiments on Balmoral Red granite at both impact and quasi-static cyclic loading.

CONTINUOUSLY CONTROLLABLE ARTIFICIAL DETRUSOR SYSTEM AND ITS CONTROL STRATEGY

In this paper, a new artificial detrusor system is proposed to achieve continuous control over the urination process and realize the normal voiding process of human (NVPH). The system is powered by a wireless power transfer (WPT) module, controlled by a control module and actuated by a shape memory alloy (SMA) spring. The design method of the SMA springs is proposed. Two control strategies are proposed to achieve NVPH. The first strategy is an open-loop control strategy based on the result of finite element analysis (FEM) simulation results and calculation of the derived system governing equations. The second strategy is a closed-loop control strategy based on the collection of feedback data and algorithmic processing. Both strategies are verified by experiments. The results show that the proposed system is feasible and both strategies can achieve NVPH. It can provide reference and guidance for the design of artificial detrusor system and formulation of control strategies.

Study on the design method of an automatic outrigger layout control system for variable outrigger layout trimaran

During the navigation of a trimaran, its wave resistance is influenced by both sailing speed and outrigger layout. In the case of a variable outrigger layout trimaran, due to the adjustability of its outrigger layout according to different speeds, its wave resistance will be lower than that of traditional trimarans. In this paper, an automatic outrigger layout control system is figured out for a variable outrigger layout trimaran. The system can control and regulate the position of outriggers according to the traveling speed in order to reduce the wave resistance during navigation. The slender ship theory based resistance calculation program is applied as the solver in this system to evaluate the wave resistance of the trimaran and further determine the optimal outrigger layout under a specific speed. In order to improve the calculation accuracy, NURBS (Non-Uniform Rational B-Splines) method is introduced to modeling the hull surface. Model tests for trimaran with 6 different outrigger layouts are conducted to obtain the resistance of the trimaran in order to validate the numerical method. The steepest descent method is applied to solve the problem of searching the outrigger layout with minimum wave resistance efficiently. On this basis, an open-loop control system for trimaran outrigger layout is designed based on PID (Proportional Integral Derivative) algorithm with the control objective derived by the solver. Finally, a outrigger layout adjustment simulation (when speed changes from Fr=0.4 to Fr=0.35) is conducted on the experimental trimaran model. By comparing the resistance results obtained by numerical method utilized in this paper to the results obtained by CFD (Computational Fluid Dynamics) simulations, the effectiveness of the proposed system is validated.

STEPPER MOTOR ANALYSIS USING ACCELERATION – DECELARATION METHOD BASED ON PLC (PROGRAMMABLE LOGIC CONTROL)

Stepper motors are one of the motor variants that are widely used in the manufacturing sector. Stepper motors have the characteristic of being able to be controlled both speed and position control in an open loop control system. The method used to control the rotation of the stepper motor is to send a series of electrical pulses with a configuration of frequency values and number of electrical pulses so that the stepper motor can control the rotational speed and angular position of the motor. Acceleration-deceleration control applies a method of gradually changing the frequency of electrical pulses by increasing the frequency every 4mS until it reaches the target frequency value. By applying the acceleration-deceleration method, the stepper motor is capable of rotating at a speed of up to 3000 rpm and the motor rotation angle position is from 10o-360o precisely, this acceleration-deceleration method can rotate the motor at a controlled speed of up to 3000 rpm.

Open-loop flow control design guided by the amplitude-frequency characteristics of the reduced-order model

Unsteady separated flow is a common flow condition causing many detrimental effects in aerospace and other fields. Open-loop control is a potential means to eliminate these drawbacks. At present, the unsatisfactory performance of open-loop control mainly attributes to the high-dimensional parameter optimization procedure and the lack of efficient knowledge-guided control law design methods. This paper proposes a method managing to directly obtain the anti-resonant frequency from the input and output amplitude-frequency characteristic curves of the reduced-order model of the flow-control coupled system. Simultaneously, a negative gain criterion is proposed to judge whether the target control effect can be achieved under the current parameter combination. For the control of low Reynolds number flow around a cylinder, the simulation results show that the optimal open-loop control frequency is 1.268 times the natural frequency of the flow, which is consistent with the anti-resonant frequency, and 26.8% of the lift fluctuation is suppressed. This paper also studies the influence of parameters such as flow frequency change, control start time, jet mass flow rate, and so on. Furthermore, control position is the key parameter affecting the amplitude-frequency characteristics. The anti-resonance points on the curves corresponding to different control positions can also guide the design of the optimal control frequency, and the negative gain criterion is still applicable. This method greatly reduces the time consumption in parameter optimization and improves the engineering application prospect of the open-loop control in unsteady separated flow control.

Position control performance analysis of linear actuator in swashplate-controlled electro hydrostatic actuation system

The position control of an energy efficient electrohydraulic actuation system is a decisive characteristic of its performance. In position control applications, a servo valve and/or variable displacement pump are vital to control the position of the linear actuator. In this open-loop control experimental work, the position of a linear actuator having a stroke length of 0.2 m is controlled by a swashplate-controlled electro hydrostatic actuation system. LabVIEW is used to create the control algorithm, and the National Instrument compact-RIO controller is used to control the voltage supply. The National Instruments controller processes sinusoidal and square demand signals at frequencies of 1/16, 1/12, 1/8, and 1/4 Hz. Open-loop control performance is predominantly dependent on the appropriate tuning of the voltage supply. Control performance is evaluated using the parameters integrated absolute error, integrated square error, integrated time absolute error, and integrated time square error. In comparison to square demand, it has been found that sinusoidal demand offers better position control accuracy, and square demand also offers appropriate control accuracy only at lower frequencies (1/16 Hz).

Modeling and Simulation of the Stepping Motor Operation Curve

To improve the open-loop control performance of stepper motors, research was conducted on their operating curves. The acceleration-velocity characteristic equations of three common operating curves were established and compared with the torque frequency characteristic curves of stepper motors. Based on this, an improved segmented correction fitting S-shaped (SCFS) curve design method based on a high torque utilization sine curve was proposed to solve the problem of rotor blockage and overshoot caused by uneven acceleration during the operation of stepper motors. In the simulation of the stepper motor load motion system, the SCFS curve was compared with common curves. The simulation results showed that the position tracking error was reduced by approximately 82% compared to the trapezoidal curve and approximately 70% compared to the exponential curve. Research has found that this method is suitable for the design of high-precision motor operating curves and has a high application value in the field of precision motion control.

SCARA TIPI 3D YAZICI TASARIMI VE İMALİ

This study designed and produced a Selective Compliance Assembly Robot Arm (SCARA)-type three-dimensional Fused Deposition Modelling (FDM) printer with three degrees of freedom based on kinematic and dynamic analyses. The dynamic capability of a SCARA robot and the FDM production method were combined, and a unique printer system was obtained by using open-source software. The Kinematic Calculations were achieved by analytical methods by using geometrical equations. An open-loop control system was created by inputting forward kinematic and inverse kinematic equations to the control software. The printing processes of the Cube and Prism samples were carried out with the SCARA-type three-dimensional printer. The data obtained from the analytical calculations and the results obtained from the experiments were compared, and the error rates in the desired and obtained prints and findings that were obtained based on print quality were shared. Academic studies on SCARA in the literature have usually focused on the dynamic calculations, design and control of SCARA robots, and especially in recent years, implementation of nature-inspired algorithms. A unique printer system was obtained by using open-source software. Prints were taken from cube and prism samples, and the samples were compared to the data obtained from the analytical results.This study implemented a form of a hybrid printer model where the movement capability of a SCARA robot was combined with FDM-type three-dimensional printer production technology. The SCARA-type three-dimensional printer was produced after making kinematic and kinetic calculations.

Ensemble controllability of parabolic type equations

In this paper, we extend the concept of ensemble controllability introduced in 2009 by Jr-Shin Li and Navin Khaneja to a class of linear partial differential equation. More precisely, we consider some abstract parabolic equation, where the system depends on some unknown parameter which is assumed to belong to a compact interval. We investigate the possibility of approximatively reaching (in L2-norm) any target state from any initial state, with an open loop control. Here the initial and target states might depend on the unknown parameter, but the control is assumed to be parameter independent.

Temperature-Controlled Laser Cutting of an Electrical Steel Sheet Using a Novel Fuzzy Logic Controller

A novel PID-type fuzzy logic controller (FLC) with an online fuzzy tuner was created to maintain stable in situ control of the cutting front temperature, aiming to enhance the laser process for thin non-oriented electrical steel sheets. In the developed controller, the output scaling factors and the universe of discourse were initially optimized using a hybrid of the particle swarm optimization and grey wolf optimization methods. The optimal parameters obtained were utilized in experiments involving the laser cutting of thin non-oriented electrical steel sheets, compared to an open-loop control system maintaining a constant cutting speed. The PID-type FLC with an online fuzzy tuner demonstrated a superior cutting quality, generating a smaller roundness and a reduced heat-affected zone (HAZ) through the in situ tuning of control parameters. Particularly, the HAZ width was significantly smaller than that reported in a previous study which used fuzzy gain scheduling for temperature control. Moreover, the cutting time was diminished by optimally adjusting the cutting speed using PID-type FLC with an online fuzzy tuner. Therefore, the accumulated heat in the steel sheet, particularly under high laser pulse frequencies, was effectively reduced, making it suitable for industrial applications.

The first distributed-mass high-performance programmable optoelectromechanical steerable motion-wave sensors focused on sophisticated biomedical applications

This paper introduces the first high-performance distributed-mass acoustic sensor made of cascaded differential phase shift suspended slot waveguide sections in a Mach–Zehnder interferometer optical transducer circuit. The heavyweight seismic mass used in traditional optoelectromechanical sensors is replaced by an fg lightweight coupling arm yielding an extra compact fast responding structure enabling utilizing over 64\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$64$$\\end{document} cascaded sections and resulting in enhancing the performance by hundreds of times. The transducer operation relies on converting the acoustic vibration into phase modulation of the light for a splendid performance. The novel sensor architecture challenges achieving optical sensitivities higher than 33×103%/g\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$33\ imes {10}^{3} \\%/\\mathrm{g}$$\\end{document} (33 times supersensitive), operating at ultrasonic acoustic speeds higher than 27 MHz, and recognizing resolutions in the 1 ng order. The programmable sensor is voltage-controlled supporting the operation in multimodes. Four operation modes are elucidated including the natural aspiration force, turbo electrostatic force open-loop voltage control, zero-force closed-loop voltage control, and dynamic turbo-force closed-loop voltage control. Wide dynamic ranges for controlling the optical sensitivity and maximum measurable acceleration up to 115.5 dB are reported. Steering capabilities of the acoustic beam in the azimuth plane are demonstrated utilizing two-spoke and three-spoke directional architectures supporting 116.64∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$116.64^\\circ$$\\end{document} and 360∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$360^\\circ$$\\end{document} of respective steering angles. Potential acoustic biosignal-based applications in the medical field are outlined.

Direct Torque Control for Series-Winding PMSM with Zero-Sequence Current Suppression Capability

The series-winding permanent-magnet synchronous motor (SW-PMSM) has the merits of high output power and excellent control performance, as does the open-winding permanent-magnet synchronous motor (OW-PMSM). Meanwhile, it can greatly reduce the number of power devices. However, due to the existence of the zero-sequence path, zero-sequence current occurs, which can cause additional losses and torque ripples. Thus, this paper proposes a novel direct torque-control strategy for the SW-PMSM with zero-sequence current suppression capability (ZSCS-DTC). First, the series-winding topology (SWT) and the voltage vector distribution in the SW-PMSM drives are analyzed. Secondly, the basic DTC (B-DTC) scheme for the SW-PMSM is investigated, and the defects of zero-sequence current open-loop control in the B-DTC scheme are revealed. Thirdly, a new voltage vector synthesis scheme is proposed for suppression of zero-sequence current while ensuring bus voltage utilization. A switching table is reconstructed with the newly synthesized voltage vectors. On this basis, a ZSCS-DTC scheme for the SW-PMSM is proposed based on zero-sequence current closed-loop control so that electromagnetic torque, stator flux linkage and zero-sequence current can be controlled simultaneously. Finally, the effectiveness of the proposed ZSCS-DTC scheme for the SW-PMSM drives is verified.

Three-degrees-of-freedom orientation manipulation of small untethered robots with a single anisotropic soft magnet

Magnetic actuation has been well exploited for untethered manipulation and locomotion of small-scale robots in complex environments such as intracorporeal lumens. Most existing magnetic actuation systems employ a permanent magnet onboard the robot. However, only 2-DoF orientation of the permanent-magnet robot can be controlled since no torque can be generated about its axis of magnetic moment, which limits the dexterity of manipulation. Here, we propose a new magnetic actuation method using a single soft magnet with an anisotropic geometry (e.g., triaxial ellipsoids) for full 3-DoF orientation manipulation. The fundamental actuation principle of anisotropic magnetization and 3-DoF torque generation are analytically modeled and experimentally validated. The hierarchical orientation stability about three principal axes is investigated, based on which we propose and validate a multi-step open-loop control strategy to alternatingly manipulate the direction of the longest axis of the soft magnet and the rotation about it for dexterous 3-DoF orientation manipulation.

Dynamic optimal control of flow front position in injection molding process: A control parameterization-based method

High dynamic and precise control of process variables within permissible limits is the key to high product quality in the injection molding industry. Among these variables, the injection flow rate of molten polymer is particularly significant. In this paper, an effective optimal open-loop and state feedback controller design method is designed to realize the optimal tracking control of the melt polymer flow front position flow of melt polymer fluid during injection molding. To this end, the dynamic model of the filling process is firstly established, taking into account the nonlinearity of hydraulic control system and the effect of molten polymer flow on the dynamics of the injection ram, and then the dynamic optimal tracking control problem of flow front position of molten polymer in injection molding machine is proposed. Then, an open-loop controller and a multi-level feedback control law are well designed, wherein the control signal and the control feedback kernels are parameterized by control parameterization. The controller design problems are transformed into sequential optimal parameter decision problems. The explicit expressions of the gradient information of the objective function and constraints on the parameters of the decision variables are solved by using the state sensitivity equation analysis method, and the gradient information is combined with the nonlinear programming algorithm to solve the optimization problems efficiently. Finally, the viability and effectiveness of the proposed design method are verified by numerical simulations.

High-Speed Virtual Flight Testing Platform for Performance Evaluation of Pitch Maneuvers

To research serious nonlinear coupling problems among aerodynamics, flight mechanics, and flight control during high maneuvers, a virtual flight testing platform has been developed for a large-scale, high-speed wind tunnel, based on the real physical environment, and it can significantly mitigate risks and reduce the costs of subsequent flight tests. The platform of virtual flight testing is composed of three-degrees-of-freedom model support, measuring devices for aerodynamic and motion parameters, a virtual flight control system, and a test model. It provides the ability to realistically simulate real maneuvers, investigate the coupling characteristics of unsteady aerodynamics and nonlinear flight dynamics, evaluate flight performance, and verify the flight control law. The typical test results of a pitch maneuver with open-loop and closed-loop control are presented, including a one-degree-of-freedom pitch motion and a two-degrees-of-freedom pitch and roll motion. The serious pitch and roll-coupled motion during a pitch maneuver at a high angle of attack is revealed, and the flight control law for decoupled control is successfully verified. The comparison of the test results and the flight data of a real pitch maneuver proves the reliability and capability of virtual flight testing.