Search Results (12)

The body roll of the tractor propagates through its rigid hitch system to the mounted implement, causing asymmetrical soil penetration depths between the implement’s lateral working elements, which affects the operational effectiveness of the implement. To address this issue, this study developed an automatic leveling system based on a dual closed-loop fuzzy Proportional-Integral-Derivative (PID) algorithm for tractor-mounted implements. The system employed an attitude angle sensor to detect implement posture in real time and utilized two double-acting hydraulic cylinders to provide a compensating torque for the implement that is opposite to the direction of the body’s roll. The relationship model between the implement’s roll angle and the actuator’s response time was established. The controller performed implement leveling by regulating the spool position and holding time of the solenoid directional valve. Simulink simulations showed that under the control of the dual closed-loop fuzzy PID algorithm, the implement’s roll angle adjusted from 10° to 0° in 1.72 s, which was 56.89% shorter than the time required by the fuzzy PID algorithm, with almost no overshoot. This demonstrates that the dual closed-loop fuzzy PID algorithm outperforms the traditional fuzzy PID algorithm. Static tests showed the system adjusted the implement roll angle from ±10° to 0° within 1.3 s. Field experiments demonstrated that the automatic leveling system achieved a maximum absolute error (MaxAE) of 0.91°, a mean absolute error (MAE) of 0.19°, and a root mean square error (RMSE) of 0.28°, with errors within 0.5° for 92.52% of the time. Results from terrain mutation tests indicate that under a sudden 5° vehicle roll angle change, the system confines implement deviation to ±1.5°. The system exhibits high control precision, stability, and robustness, fulfilling the demands of tractor-mounted implement leveling. Full article

This study presents a pneumatic proportional pressure valve employing a silicon microfluidic chip (SMC) integrated with a V-shaped electrothermal microactuator, aiming to address the limitations of traditional solenoid-based valves in miniaturization and high-precision control. The SMC, fabricated via MEMS technology, leverages the thermal expansion of microactuator ribs to regulate pressure through adjustable orifices. A first-order transfer function between input voltage and displacement of the microactuator was derived through theoretical modeling and validated via COMSOL Multiphysics 5.2a simulations. Key geometric parameters of the actuator ribs—cross-section, number, inclination angle, width, span length and thickness—were analyzed for their influence on lever mechanism displacement, actuator displacement, static gain and time constant. AMESim 16.0-based simulations of single- and dual-chip valve structures revealed that increasing ζ shortens step-response rise time, while reducing τ improves hysteresis. Experimental validation confirmed the valve’s static and dynamic performance, achieving a step-response rise time of <40 ms, linearity within the 30–60% input voltage range, and effective tracking of sinusoidal control signals up to 8 Hz with a maximum pressure deviation of 0.015 MPa. The work underscores the potential of MEMS-based actuators in advancing compact pneumatic systems, offering a viable alternative to conventional solenoids. Key innovations include geometry-driven actuator optimization and dual-chip integration, providing insights into high-precision, low-cost pneumatic control solutions. Full article

This study presents the design and analysis of a proportional solenoid used in electro-pneumatic brake systems for heavy vehicles. The solenoid was designed using a traditional method, and its static and dynamic characteristics were investigated both theoretically and experimentally. ANSYS 2024 R1 Maxwell was employed for theoretical static analysis, focusing on the effects of the geometric dimension parameters in the fixed and moving pole contact regions on the force–displacement characteristics. The optimal dimensions for proportionality were determined under constraint parameters. The static analysis results provided the magnetization curve data, which were used to create Look-Up Tables for a dynamic model in MATLAB R2024b-Simulink, and this method reduced the simulation time and increased the dynamic simulation accuracy. Following static analysis, a prototype electromagnet was manufactured and tested. The solenoid achieved a constant magnetic force of 45 ± 3 N with a current of 1.3 A over a working range of 1–3 mm. The dynamic model, incorporating data from ANSYS, yielded results that closely matched the experimental findings. Full article

The influence of key design parameters on the constant force characteristics of long-stroke moving-iron proportional solenoid actuators (MPSAs) has been explored by a method combining finite element modelling and correlation analysis. First, the finite element model (FEM) of long-stroke MPSA was developed and validated. Subsequently, the two evaluation indexes, the average-output solenoid force and maximum-output solenoid force variability, were introduced to disclose the influence law of pole shoe parameters on the constant force characteristics of a long-stroke MPSA. After that, correlation analysis was employed to quantify the influence of several parameters and parameter interaction factors on the constant force characteristics. The results indicate a strong contradiction between the average-output solenoid force and maximum-output solenoid force variability; however, increasing the inner diameter of the cone helps enhance the average-output solenoid force without causing maximum-output solenoid force variability to increase. Among all the parameters examined, the cone angle is the most significant parameter affecting the constant force characteristics. Additionally, interactions between the cone angle and the cone length, the cone angle and the inner cone diameter, the cone angle and the outer cone diameter, the cone length and the outer cone diameter, as well as the inner cone diameter and the outer cone diameter also have an important influence on the constant force characteristics. This study deepens our understanding of how the key parameters affect the constant force characteristics and assists designers in optimizing these parameters for developing new structures. Full article

The autonomous control of landing procedures can provide the efficiency and precision that are vital for the successful, safe completion of space operations missions. Controlling a lander with this precision is challenging because the propellants, which will be expended during the operations, represent a significant fraction of the lander’s mass. The mass variation of each tank profoundly influences the inertia and mass characteristics as thrust is generated and complicates the precise control of the lander state. This factor is a crucial consideration in our research and methodology. The dynamics model for our lander was developed where the mass, inertia, and center of mass (COM) vary with time. A feed-forward neural network (NN) is incorporated into the dynamics to capture the time-varying inertia tensor and COM. Moreover, the propellant takes time to travel through the feed lines from the storage tanks to the engine; also, the solenoid valves require time to open and close. Therefore, there are time delays between the actuator and the engine response. To take into account these sources of variations, a combined time delay is also included in the control loop to evaluate the effect of delays by fluid and mechanisms on the performance of the controller. The time delay is estimated numerically by a Computational Fluid Dynamics (CFD) model. As part of the lander’s control mechanism, a thrust vector control (TVC) with two rotational gimbals and a reaction control system (RCS) are incorporated into the dynamics. Simple proportional, integral, and derivative (PID) controllers are designed to control the thrust, the gimbal angles of the TVC, and the torque required by the RCS to manipulate the lander’s rotation and altitude. A complex mission with several numerical examples is presented to verify the hover and rotational motion control. Full article

In this study, the performance of a long-stroke moving-iron proportional solenoid actuator (MPSA) was improved by combining numerical simulations and experiments. A finite element model of the MPSA was developed; its maximum and mean relative absolute errors of electromagnetic force were 4.3% and 2.3%, respectively, under typical work conditions. Seven design parameters including the cone angle, cone length, depth of the inner hole of the coil skeleton, cone width of the armature, inner cone diameter, and initial position of the moving-iron core were selected for developing the model, and the coefficient of the variation in electromagnetic force, nominal acceleration, 95% of the maximum stable output electromagnetic force, and corresponding response time were used as the performance indicators. The constraint relation between each performance indicator and the influence of each design parameter on the performance indicators were revealed using the uniform Latin hypercube experiment design, correlation analysis, and the main effect analysis method. A multi-objective optimization mathematical model of the MPSA was developed by combining traditional surrogate and machine learning models. The Pareto solution set was obtained using the nondominated sorting genetic algorithm II (NSGA-II), and three decision schemes with different attitudes were determined using the Hurwicz multi-criteria decision-making method. The results showed that a strong contradiction exists among the 95% of the maximum stable output electromagnetic force and its corresponding response time and the coefficient of the variation in electromagnetic force. The cone angle considerably influenced the performance indicators. Compared with the initial design, the coefficient of the variation in electromagnetic force was reduced by 54.08% for the positive decision, the corresponding response time was shortened by 15.65% for the critical decision, and the corresponding acceleration was enhanced by 10.32% for the passive decision. Thus, the overall performance of the long-stroke MPSA effectively improved. Full article

This paper addresses the design, fabrication and control of Fabric Inflatable Soft Actuators (FISAs) for driving Soft Wearable Devices (SWD) for rehabilitation or assistance tasks. FISAs are integrated by a set of pneumatic chambers made of 200D TPU-nylon that create bending-extending motions using a modular assembly that allow FISAs to adapt them to any size of limb or easily replace them. Regarding FISAs fabrication, a self-hand manufacturing approach has been used for cutting, sewing, and joining them. Additionally, to evaluate FISAs operation, a Soft Exo-Sleeve called MOSAR system was manufactured to achieve elbow motion. To control their inflation-deflation process in real-time, proportional and solenoid valves have been implemented along with a Proportional-Derivative (PD) control strategy that has been embedded in the NUCLEO-STM32F767ZI™ board with rapid control prototyping. Preliminary experiments about FISA performance on the MOSAR system were carried out to measure the inflation-deflation time, Range of Motion (ROM), and output force when elbow flexion-extension occurred in a dummy limb. The results have demonstrated FISAs functionality above the exosuit since they were able to lift 1 kg with flexion of 130${}^{°}$ in 5 s using 50 psi. Therefore, FISAs represent a feasible choice for semicircular motions in other joints such as the wrist, hand, or knee, no matter age, limb, or size, only the number of FISAs must be adjusted on the MOSAR system. Full article

Insect behaviors, such as flying, oviposition, parasitism, mating/calling, response to semiochemicals, and others, might be influenced by barometric pressure fluctuations. Abiotic factors controlled in the laboratory facilitate the observation of particularities related to development, behavior, and/or habits of arthropods and plants and their interactions. This study aimed to design an automated barometric chamber for research on arthropod behaviors and insect–plant interactions in the laboratory. The barometric chamber is a transparent box equipped with a single-board computer. An air pump and two proportional solenoid valves were used as actuators to control the air flow, while barometric pressure, air humidity, and temperature sensors were used to monitor the conditions within the chamber. A graphical user interface to operate the barometric chamber was developed to run in a web browser. The barometric chamber was designed to allow the barometric pressure to be changed by up to 15 hPa with respect to the local barometric pressure. In addition, the control system makes it possible to set the rise/fall time (ramp) corresponding to the duration in which a change of pressure will be conditioned. Short- and long-term evaluations demonstrated that the control system can assure pressure stability of ±0.1 hPa with respect to the setpoint value. For demonstration purposes, two experiments were carried out to evaluate the influence of barometric pressure on the feeding activity of Euschistus heros and Diabrotica speciosa. For E. heros, the number of stylet sheath was significantly increased under high pressure conditions compared to the low pressure. However, for D. speciosa, there was no statistical difference in leaf consumption at the evaluated testing conditions. Full article

A control chip with a multistage flow-rate regulation function based on the correlation between the flow resistance and flow rate has been developed in this article. Compared with the traditional proportional solenoid valve, this kind of flow valve based on microfluidic technology has the characteristics of being light-weight and having no electric drive. It solves such technical problems as how the current digital microfluidic chip can only adjust the flow switch, and the adjustment of the flow rate is difficult. To linearize the output signal, we propose a design method of weighted resistance. The output flow is controlled by a 4-bit binary pressure signal. According to the binary value of the 4-bit pressure signal at the input, the output can achieve 16-stage flow adjustment. Furthermore, we integrate the three-dimensional flow resistance network, multilayer structure microvalve, and parallel fluid network into a single chip by using 3D printing to obtain a modular flow control unit. This structure enables the microflow control signal to be converted from a digital signal to an analogue signal (DA conversion), and is suitable for microflow driving components, such as in microfluidic chip sampling systems and proportional mixing systems. In the future, we expect this device to even be used in the automatic control system of a miniature pneumatic soft actuator. Full article

The active hydraulic mount with solenoid actuator (AHM-SNA) does not require permanent magnets, is of low cost, and has attracted wide attention. This paper focuses on each link of the secondary path in AHM-SNA, the transfer functions (TFs) were studied one by one, and a simple and efficient expression for the total secondary path is discussed. First, based on the mathematical model of the hydraulic mount with inertia track and decoupling membrane, the TF from actuator active force to output force at frame side was analyzed, the results show that the TF was constant in the mid-frequency band. Second, based on the geometric parameters and cone air gap of solenoid actuator, it was obtained that the TF from the square of current to actuator active force is also constant; based on the relationship that the active force frequency is twice of the harmonic current frequency, the full-wave-rectified current was introduced. Utilizing the fact that the second harmonic component of the current is the main component, it was concluded that the total TF of the secondary path from current to active force and then to output force at frame side was constant in the mid-frequency band. Finally, two sets of experiments with full-wave-rectified current as the excitation were carried out, and the analytical conclusion was verified that the TF of the secondary path was constant as a proportional link and was convenient for the active control algorithms. Full article

This study presents a simulation model, optimization strategy and the experimental validation of a solenoid electromagnetic actuator that is widely used in industry components, especially in pneumatic/hydraulic valves. In the preliminary design, a two-dimensional magnetostatic finite element analysis (FEA) model is proposed and verified by static push-force comparisons between the two-dimensional FEA model, the three-dimensional FEA model and the experimental results. Then, a static and dynamic performance improvement strategy is proposed. To optimize the static push-force of the actuator, a static multi-objective optimization strategy for actuator structure parameters was developed based on a genetic algorithm. An experimental analysis of dynamic performance was carried out to improve the dynamic response of the actuator. By using a high-precision measuring device in the static-push-force test and dynamic direct current-input-signal tests, the comparisons results between the manufactured conventional actuator and the manufactured optimal actuators showed that the proposed optimization strategy was feasible. Through the static optimization strategy, the average static push-force in the working stroke was improved by 21.8%. Moreover, through the dynamic optimization strategy, the cutoff frequency of the push force response was improved by 129.1%, 79.6% and 74.3%, respectively, at three key positions in the working stroke. Full article

This research developed a novel proportional pressure control valve for an automobile hydraulic braking actuator. It also analyzed and simulated solenoid force of the control valves, and the pressure relief capability test of electromagnetic thrust with the proportional valve body. Considering the high controllability and ease of production, the driver of this proportional valve was designed with a small volume and powerful solenoid force to control braking pressure and flow. Since the proportional valve can have closed-loop control, the proportional valve can replace a conventional solenoid valve in current brake actuators. With the proportional valve controlling braking and pressure relief mode, it can narrow the space of hydraulic braking actuator, and precisely control braking force to achieve safety objectives. Finally, the proposed novel proportional pressure control valve of an automobile hydraulic braking actuator was implemented and verified experimentally. Full article