Oil cylinder synchronous method based on PID algorithm

Abstract

The invention belongs to the field of hydraulic systems and discloses an oil cylinder synchronous method based on the PID algorithm. The method includes the following steps that firstly, a programmable controller outputs a signal through the analog quantity to control a proportional overflow valve according to the load characteristic; secondly, a synchronous running mode of a hydraulic system is selected, functions of target positions of all oil cylinders relative to time are obtained; thirdly, the functions obtained in the second step serve as the input, position or force information collected by a sensor serves as the feedback, the output control quantity corresponding to each oil cylinder at each moment is calculated, and therefore the opening size and direction of a servo reversing valve installed in each oil cylinder can be adjusted; and fourthly, subtracting is conducted on the current positions or output force, detected by the sensor, of the two oil cylinders during running, the obtained value serves as the given input of a third PID controller, and the output of the third PID controller acts on the input of the function of each oil cylinder relative to time, the positioning synchronous precision or the output force synchronous precision of the oil cylinders are effectively improved.

Description

technical field [0001] The invention belongs to the field of hydraulic systems, and more specifically relates to a method for synchronizing oil cylinders. Background technique [0002] The output force synchronization or position synchronization of the traditional multi-cylinder synchronous operation is mainly realized by the synchronous valve, which is easily affected by machining errors, use environment, and equipment wear, and it is difficult to meet the high-precision synchronous operation requirements of the cylinders. [0003] The existing schemes for synchronous control of oil cylinders ignore the influence of the output oil pressure of the hydraulic oil cylinder and the loss of oil pressure in the pipeline on the control accuracy of the system. [0004] In terms of control algorithm, the patent application No. 201520154944.4 discloses an automatic synchronous control system with a single proportional valve and two cylinders. One cylinder is used as the master cylinde...

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Problems solved by technology

[0002] The output force synchronization or position synchronization of the traditional multi-cylinder synchronous operation is mainly realized by the synchronous valve, which is easily affected by machining errors, use environment, and equipment wear, and it is difficult to meet the high-precision synchronous operation requirements of the cylinders.

[0003] The existing schemes for synchronous control of oil cylinders ignore the influence of the oil pressure output by the hydraulic oil cylinder and the loss of oil pressure in the pipeline on the control accuracy of the system.

[0004] In terms of control algorithm, the patent application No. 201520154944.4 discloses an automatic synchronous control system with a single proportional valve and two cylinders. One cylinder is used as the master cylinder and the other cylinder is the slave cylinder. "Slave follower active", this kind of scheme will inevitably make the position of the master cylinder ahead of the slave cylinder, and the two cannot achieve precise synchronization in dynamics

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