In order to solve the problems of difficult control, poor stability, and low control precision in complex autonomous non‐linear systems, and some sensors have non‐linear errors in special environments. Based on the PSO (Particle Swarm Optimization) algorithm, an PSO‐BP‐PID (Particle Swarm Optimization Back Propagation neural network PID) control method and a sensor error compensation algorithm based on BP (Back Propagation) neural network are designed for optimal temperature and humidity control and sensor error compensation in the autonomous greenhouse system. The error between the average temperature value and the target value after steady state is 0.5°C, and the error between the average humidity value and the target value is 1% RH. The results show that the control method can effectively compensate the non‐linear error of the sensor and improve the performance of the control system in a complex environment, which is suitable for the stable and control of actuators in autonomous systems. The error of temperature and humidity sensor is compensated by BP neural network; PSO (Particle Swarm Optimization) was used to optimize the BP‐PID parameters of the automatic greenhouse system.
Purpose Vehicle lightweight design has positive implications for reducing energy consumption and abating greenhouse gas emissions. The traditional trailer axle design mainly focuses on the overall performance of the trailer axle. Only when the local performance does not meet the requirements will local performance optimization be done, such as local heat treatment to improve local strength. Such a design results in an uneven distribution of axle performance and excess performance in some local structures. The purpose of this study is to investigate the weight reduction on the premise of ensuring the structural dimensions of the outer surface of the axle remain unchanged and the reliability of the axle. Design/methodology/approach The axle is parameterized by computer aided design, and the optimized axle finite element model based on computer aided engineering is established and verified by taking the eight dimensions of the axle cavity structure which affect the performance as parameters. A genetic algorithm is used to optimize the axle cavity structure size and axle weight based on multiobjective optimization, and eight optimized size parameters of axle cavity structure are obtained. Findings The total weight of the optimized axle of TM1314 is reduced by 10.2 kg, and the weight reduction ratio reaches 10.7%. According to the optimized structural size of the axle, the specimen was trial-manufactured, and the bench tests of stiffness, strength and fatigue life were carried out according to the test requirements of the trailer axle standard (JT/T 475-2002). The test results show that the maximum deformation of the specimen is 2.46 mm, the strength safety factor of the specimen body and the steel plate spring seat are 6.71 and 6.86 and bear the alternating load more than 1.05 × 106 times, which meets the standard of the trailer axle and is better than the original design requirements of the trailer axle. Originality/value In this study, the multiobjective optimization model of the axle is established, the response surface is constructed by the Latin hypercube sampling design method and the optimal solution set is obtained by the multiobjective genetic algorithm. It has been verified by bench tests that it can achieve a weight reduction of 10.7% under the premise of the same structure and size of the outer surface of the axle. The lightweight method based on multiobjective optimization proposed in this paper can provide a reference for the lightweight design of other key vehicle components.
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