Force Compensation Control for Electro-Hydraulic Servo System with Pump-Valve Compound Drive via QFT-DTOC

Each joint of a hydraulic-driven legged robot adopts a highly integrated hydraulic drive unit(HDU),which features a high power-weight ratio.However,most HDUs are throttling-valve-controlled cylinder systems,which exhibit high energy losses.By contrast,pump control systems offer a high efficiency.Nevertheless,their response ability is unsatisfactory.To fully utilize the advantages of pump and valve control systems,in this study,a new type of pump-valve compound drive system(PCDS)is designed,which can not only effectively reduce the energy loss,but can also ensure the response speed and response accuracy of the HDUs in robot joints to satisfy the performance requirements of robots.Herein,considering the force control requirements of energy conservation,high precision,and fast response of the robot joint HDU,a nonlinear mathematical model of the PCDS force control system is first introduced.In addition,pressure-flow nonlinearity,friction nonlinearity,load complexity and variability,and other factors affecting the system are considered,and a novel force control method based on quantitative feedback theory(QFT)and a disturbance torque observer(DTO)is designed,which is denoted as QFT-DTOC herein.This method improves the control accuracy and robustness of the force control system,reduces the effect of the disturbance torque on the control performance of the servo motor,and improves the overall force control performance of the system.Finally,experimental verification is performed using the PCDS performance test platform.The experimental results and quantitative data show that the QFT-DTOC proposed herein can significantly improve the force control performance of the PCDS.The relevant force control method can be used as a bottom-control method for the hydraulic servo system to provide a foundation for implementing the top-level trajectory planning of the robot.

Application of a compound controller based on fuzzy control and support vector machine to ship's boiler-turbine coordinated control system

Multivariables, strong coupling, nonlinearity, and large delays characterize the boiler-turbine coordinated control systems for ship power equipment. To better deal with these conditions, a compound control strategy based on a support vector machine （SVM） with inverse identification was proposed and applied to research simulating coordinated control systems. This method combines SVM inverse control and fuzzy control, taking advantage of the merits of SVM inverse controls which can be designed easily and have high reliability, and those of fuzzy controls, which respond rapidly and have good anti-jamming capability and robustness. It ensures the controller can be controlled with near instantaneous adjustments to maintain a steady state, even if the SVM is not trained well. The simulation results show that the control quality of this fuzzy-SVM compound control algorithm is high, with good performance in dynamic response speed, static stability, restraint of overshoot, and robustness.

Simulation of Greenhouse Heating System Using Fuzzy Smith Cascade Compound Control

Aiming at characteristic of time delay, time-varying parameters and much disturb in glass greenhouse heating system, fuzzy smith cascade compound control policy based on typical PID cascade compound control policy is proposed. Simulation results show that it is effective to overcome the influence of time delay on stability of control system and the system possesses strong robust and good dynamic performance..

Release Characteristics of Different N Forms in an Uncoated Slow/Controlled Release Compound Fertilizer

This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer （UCRF） and the N uptake and N-use efficiency by rice plants. Water dissolution, soil leaching, and pot experiments were employed. The dynamics of N release from the UCRF could be quantitatively described by three equations： the first-order kinetics equation [N1=N0 （1-e^-kt）], Elovich equation （N1=a ＋ blnt）, and parabola equation （N1=a ＋ bt^0.5）, with the best fitting by the first-order kinetics equation for different N （r= 0.9569^＊＊-0.9999^＊＊）. The release potentials （No values estimated by the first-order kinetics equation） of different N in the UCRF decreased in the order of total N 〉 DON 〉 urea-N 〉 NH4^＋-N 〉 NO3^-N in water, and total N 〉 NH4^＋-N 〉 DON 〉 urea-N 〉 NO3^--N in soil, respectively, being in accordance with cumulative amounts of N release. The constants of N release rate （k values and b values） for different N forms were in decreasing order of total N 〉 DON 〉 NH4^＋-N 〉 NO3^--N in water, whereas the k values were urea- N 〉DON 〉 NH4^＋-N 〉 total N 〉 NO3^--N, and the b values were total N 〉 NH4^＋-N 〉 DON 〉 NO3^--N 〉 urea-N in soil. Compared with a common compound fertilizer, the N-use efficiency, N-agronomy efficiency, and N-physiological efficiency of the UCRF were increased by 11.4%, 8.32 kg kg^-1, and 5.17 kg kg^-1, respectively. The ratios of different N to total N in the UCRF showed significant correlation with N uptake by rice plants. The findings showed that the first-order kinetics equation [Nt=N0 （l-e^kt）] could be used to describe the release characteristics of different N forms in the fertilizer. The UCRF containing different N forms was more effective in facilitating N uptake by rice compared with the common compound fertilizer containing single urea-N form.

Impact dynamics analysis of free-floating space manipulator capturing satellite on orbit and robust adaptive compound control algorithm design for suppressing motion

The impact dynamics, impact effect, and post-impact unstable motion sup- pression of free-floating space manipulator capturing a satellite on orbit are analyzed. Firstly, the dynamics equation of free-floating space manipulator is derived using the sec- ond Lagrangian equation. Combining the momentum conservation principle, the impact dynamics and effect between the space manipulator end-effector and satellite of the cap- ture process are analyzed with the momentum impulse method. Focusing on the unstable motion of space manipulator due to the above impact effect, a robust adaptive compound control algorithm is designed to suppress the above unstable motion. There is no need to control the free-floating base position to save the jet fuel. Finally, the simulation is proposed to show the impact effect and verify the validity of the control algorithm.

Robust controller design for compound control missile with fixed bounded convergence time

A robust controller for bank to turn(BTT) missiles with aerodynamic fins and reaction jet control system(RCS) is developed based on nonlinear control dynamic models comprising couplings and aerodynamic uncertainties. The fixed time convergence theory is incorporated with the sliding mode control technique to ensure that the system tracks the desired command within uniform bounded time under different initial conditions. Unlike previous terminal sliding mode approaches, the bound of settling time is independent of the initial state, which means performance metrics like convergence rate can be predicted beforehand. To reduce the burden of control design in terms of robustness, extended state observer(ESO) is introduced for uncertainty estimation with the output substituted into the controller as feedforward compensation. Cascade control structure is employed with the proposed control law and therein the compound control signal is obtained.Afterwards, control inputs for two kinds of actuators are allocated on the basis of their inherent characteristics. Finally, a number of simulations are carried out and demonstrate the effectiveness of the designed controller.

Compound control allocation strategy of dual aero/jet vane control missile

To solve the control allocation problem of dual aero/jet vane control missile, dynamics e- quations in longitudinal plane are derived, and the structure of compound control loop is designed based on attitude autopilot. Four brief compound control allocation strategies are researched and an- alyzed. Furthermore, a new strategy called chain combination variable proportional coefficient strat- egy based on rudder effect is presented. By simulation of initial climb trajectory, the characteristics of all the strategies are researched, and the results illustrate that the new strategy can meet the re- quirement well.

Compound control for speed and tension multivariable coupling system of reversible cold strip mill

To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.

Suppression of Amplitude Decoherence in Arbitrary n-Level Atom in -Configuration with Bang-Bang Controls

In this paper, we give Bang-Bang （BB） decoupling schemes to suppress the amplitude decoherence in the five-and six-level atom systems in ≡-configuration. We generalize this scheme to the arbitrary level atom system in ≡-configuration. The corresponding decoupling operators are given explicitly.

Modeling and Control of Nonlinear Discrete-time Systems Based on Compound Neural Networks

An adaptive inverse controller for nonliear discrete-time system is proposed in this paper. A compound neural network is constructed to identify the nonlinear system, which includes a linear part to approximate the nonlinear system and a recurrent neural network to minimize the difference between the linear model and the real nonlinear system. Because the current control input is not included in the input vector of recurrent neural network (RNN), the inverse control law can be calculated directly. This scheme can be used in real-time nonlinear single-input single-output (SISO) and multi-input multi-output (MIMO) system control with less computation work. Simulation studies have shown that this scheme is simple and affects good control accuracy and robustness.

Research on Trim Control of Compound High Speed Helicopter

An investigation is conducted on optimizing the control allocation for trimmed flight on the compound helicopter.The compound helicopter features a single main rotor,a vectored thrust ducted propeller(VTDP)and lifting wings.Due to the redundant controls for thrust,elevator deflection,and differential and symmetric flap deflection,there is a wide range of trim solutions in forward flight for compound helicopter.A method is developed to calculate optimal trim solutions.Firstly,aerodynamics models for deferent subsystems of the compound helicopter are conducted,which consider the mutual interaction of each part.Secondly,a flight dynamics model is developed based on which the method of trim optimization is performed.Finally,the method is demonstrated using a compound helicopter UH 60L/VTDP.The trim optimization of flight conditions from hover to 370 km/h is conducted using the optimization method.The controls,fuselage attitudes as well as the allocation of lift and thrust along with the flight speed are obtained.

ELECTRO-HYDRAULIC COMPOUND CONTROL METHOD AND CHARACTERISTIC OF CONTROL FOR TENSION SYSTEM WITH HIGH INERTIA LOADS

Based on the pressure regulation circuit adopting electro-hydraulic proportional relief valve to control tension, a new type of electro-hydraulic compound control circuit with throttle control unit is presented, which can obtain optimal dynamic damping ratio through real-time altering pressure-flow gain of the throttle control unit, improve the dynamic characteristic of tension follow-up control for the tension system with high inertia loads. Moreover, the characteristic when the cable linear velocity variation causes change of tension is investigated, and a compound control strategy is proposed. The theoretical analysis and experimental results show that the electro-hydraulic compound control circuit is effective and the characteristic of the compound control strategy is satisfactory.

Precise Compound Control of Loading Force for Electric Load Simulator of Electric Power Steering Test Bench

Electric load simulator(ELS) systems are employed for electric power steering(EPS) test benches to load rack force by precise control. Precise ELS control is strongly influenced by nonlinear factors. When the steering motor rapidly rotates, extra force is directly superimposed on the original static loading error, which becomes one of the main sources of the final error. It is key to achieve ELS precise loading control for the entire EPS test bench. Therefore, a three-part compound control algorithm is proposed to improve the loading accuracy. First, a fuzzy proportional–integral plus feedforward controller with force feedback is presented. Second, a friction compensation algorithm is established to reduce the influence of friction. Then, the relationships between each quantity and the extra force are analyzed when the steering motor rapidly rotates, and a net torque feedforward compensation algorithm is proposed to eliminate the extra force. The compound control algorithm was verified through simulations and experiments. The results show that the tracking performance of the compound control algorithm satisfies the demands of engineering practice, and the extra force in the ELS system can be suppressed by the net torque corresponding to the actuator’s acceleration.

Research into stope roof control of compound roof by solid backfilling mining

Based on the analysis of the failure characteristics and backfilling effect of the compound roof at 1801 backfilling workface in Taiyuan coal mine, China, we propose a method of controlling the pre- subsidence of a compound roof by using pre-stressed bolts to improve the backfilling ratio of the work- face so as to maintain the global stability of the stope roof. In addition, PHASE simulation software was employed to analyze the influence law of pre-stressing force, length, and interval on roof subsidence at the workface. On the basis of the numerical simulation results, a model for calculating the pre-stressing force and length of the bolts, the interval between the bolts, as well as roof subsidence at the workface, was established by using SPSS regression analysis software. Moreover, the research results were applied successfully to the 1801 filling workface. According to the monitoring data of roof closure, it was found that the final subsidence value for the goal roof was 350 mm and the filling ratio at the workface was 86%, which could fully meet the demand for safety production at the workface. The safe and effective control of the stope roof was therefore realized, which achieves the goal of safe and efficient backfilling mining under a compound roof.

Iron Fertilization with Enhanced Phytoplankton Productivity under Minimal Sulfur Compounds and Grazing Control Analysis in HNLC Region

The present study investigated quantitatively the significance of HNLC (high-nutrient low-chlorophyll) regions and its grazing control with the improved iron fertilization for climate change. The limitation of iron (Fe) for phytoplankton growth in HNLC regions was confirmed by sulfur compounds (S) such as volcanic ash and hydrogen sulfide (H2S) in batch cultures, whose chemical sediment of Fe3S4 showed 4.06 wt%. The technologies developed for iron fertilization since 1993 till now were not practical to provide sufficient amounts of bioavailable iron due to sedimentary iron sulfides induced by undersea volcanic sulfur compounds. The proposed technology for iron fertilization was improved to enhance the bioavailable iron to phytoplankton by keeping minimal sulfur compounds in HNLC regions. The low productivity of phytoplankton by grazing control in HNLC regions was 6% diatoms whose 52% was grazed by copepods and 42% by krill on the basis of data analysis in 2000 EisenEx Experiment at boundary of Antarctic and African tectonic plates. All of the previous iron fertilization experiments were conducted at volcanic sulfur compounds enriched HNLC regions. The present study revealed that the enhanced phytoplankton productivity in batch culture without sedimentary iron sulfides can be possible only if sulfur compounds are minimal, as is in Shag Rocks (53°S, 42°W) of South Georgia in Scotia Sea in the Southern Ocean.

Experimental study of the movement of control fluid in compound perforation

The interaction between the high pressure gas and the control fluid and the movement mechanism of the control fluid in compound perforation were studied by a series of large-scale experiments, where the movement behavior of the control fluid was observed. The curves of measured pressure were analyzed, a mathematical model for the rigid movement of the control fluid was established, and the movement velocity of control fluid was analyzed. Moreover, the velocity from experimental results and velocity from an analytical solution were contrasted. The movement of the control fluid in the initial stage was similar to the rigid movement; however, the propagation of the pressure wave in the control fluid should be taken into account. Experimental results are significant for research on the movement mechanism of control fluid in compound perforation.

Adaptive Backstepping Control for Uncertain Systems with Compound Nonlinear Characteristics

An adaptive backstepping multi-sliding mode approximation variable structure control scheme is proposed for a class of uncertain nonlinear systems.An actuator model with compound nonlinear characteristics is established based on the model decomposition method.The unmodeled dynamic term of the radial basis function neural network approximation system is presented.The Nussbaum gain design technique is utilized to overcome the problem that the control gain is unknown.The adaptive law estimation is used to estimate the upper boundary of neural network approximation and uncertain interference.The adaptive approximate variable structure control effectively weakens the control signal chattering while enhancing the robustness of the controller.Based on the Lyapunov stability theory,the stability of the entire control system is proved.The main advantage of the designed controller is that the compound nonlinear characteristics are considered and solved.Finally,simulation results are given to show the validity of the control scheme.

Evaluation of the Effects of High-efficiency Compound Formulations on the Prevention and Control of Sugarcane Brown Rust

[Objectives]This study was conducted to screen high-efficiency compound formulations and precise application technologies for the prevention and control of sugarcane brown rust. [Methods] Zineb, dinconazole, mancozeb, azoxystrobin, pyraclostrobin, difenoconazole·azoxystrobin, chlorothalonil and carbendazim were selected for field efficacy tests. [Results] Four formulations,(65% zineb WP 1 500 g+75% chlorothalonil WP 1 500 g+potassium dihydrogen phosphate 2 400 g+agricultural synergist 300 ml)/hm^(2),(12.5% dinconazole WP 1 500 g +75% chlorothalonil WP 1 500 g+potassium dihydrogen phosphate 2 400 g+agricultural synergist 300 ml)/hm^(2),(80% mancozeb WP 1 500 g+75% chlorothalonil WP 1 500 g+potassium dihydrogen phosphate 2 400 g+agricultural synergist 300 ml)/hm^(2) and(30% difenoconazole·azoxystrobin SC 900 ml+potassium dihydrogen phosphate 2 400 g+agricultural synergist 300 ml) had good control efficacy on sugarcane brown rust, and showed disease indexes all below 18.79 and control efficacy over 80.53%. The four formulations are ideal high-efficiency compound formulations for the prevention and control of sugarcane brown rust. They can be sprayed manually and by unmanned aerial vehicles on the foliar surface from July to August, once every 7 to 10 d, continuously for 2 times. [Conclusions] This study provides new technical support for accurate and efficient prevention and control of sugarcane rust.

Evaluation of the Effect of High-efficiency Compound Formulations on the Prevention and Control of Sugarcane Brown Stripe

[Objectives]This study was conducted to screen high-efficiency compound formulations and precise application technologies for the prevention and control of sugarcane brown stripe disease.[Methods]Carbendazim,benomyl,chlorothalonil,azoxystrobin,pyraclostrobine and difenoconazole·azoxystrobin were selected for field efficacy tests.[Results]Three formulations,(50%carbendazim WP 1500 g+75%chlorothalonil WP 1500 g+potassium dihydrogen phosphate 2400 g+agricultural synergist 300 ml)/hm^(2),(50%benomyl WP 1500 g+75%chlorothalonil WP 1500 g+potassium dihydrogen phosphate 2400 g+agricultural synergist 300 ml)/hm^(2) and(25%pyraclostrobin 600 ml+potassium dihydrogen phosphate 2400 g+agricultural synergist 300 ml)/hm^(2) had good control effects on sugarcane brown stripe disease,and showed disease index below 14.02 and control efficacy above 84.41%.The three formulations are ideal high-efficiency compound formulations for the prevention and control of sugarcane brown stripe disease.They can be sprayed manually and by unmanned aerial vehicles on the foliar surface from July to August,once every 7 to 10 d,continuously for 2 times.[Conclusions]This study provides new technical support for accurate and efficient prevention and control of sugarcane brown stripe disease.

Compound Kushen injection combined with chemotherapy in the treatment of gastric cancer: a meta-analysis of randomized controlled trials

Objective: This study aims to systematically evaluate the efficacy and safety of compound kushen injection (CKI) in combination with chemotherapy in patients with gastric cancer (GC). Methods: A comprehensive electronic search was conducted by searching PubMed, EMBASE, Cochrane Library, Chinese Biological Medical disc, China National Knowledge Infrastructure and Wanfang databases (the last update January 20, 2018). All randomized controlled trials (RCTs) of CKI plus chemotherapy versus chemotherapy alone in GC patients were identified. The quality of each study was evaluated using the Jadad’s scale, and the meta-analysis was performed using Review Manager 5.3 and STATA 14 software. Results: A total of nine studies on 688 cases were included in this study. The results showed that CKI combined with chemotherapy had a better effect on improving patients’ overall response rate (ORR) and life quality. The consequences of Egger’s and Begg’s tests showed there was no significant publication bias. Conclusion: The current evidence showed that CKI may enhance the clinical efficacy of chemotherapy, improve the quality of life and increase the safety in patients with gastric cancer.