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0 Introduction

Since the successful holding of the annual Asia international logistics technology and transportation system exhibition and China International Import Expo, the automated three-dimensional warehouse has developed rapidly in China, extending from terminal storage to production process, with a higher degree of automation and a high degree of integration of Internet of things information. It is widely used in the pharmaceutical industry, automobile manufacturing, machinery manufacturing, tobacco industry, airport freight, textile industry, printing, chemical industry and other fields.

As the key equipment of automated warehouse, stacker plays a key role in the process of product storage and distribution. The higher the production efficiency of an enterprise, the higher the requirements for the access efficiency of the stacker in the roadway and the refinement degree of the stacker. The stacker system is composed of mechanical, electrical and software, which are integrated efficiently. Through the software scheduling system, the command is sent to the stacker. According to the received operation command and storage address, the PLC control system of the stacker shuttles back and forth in the shelf roadway to pick up or send the goods to the conveyor. How to ensure the stacker operation more efficient, safe and environmental protection has become the focus of professional engineers.

1 project background

Qingdao machinery and equipment manufacturing Co., Ltd. is a leader in the field of domestic livestock and poultry breeding machinery. The company integrates product R & D, engineering design, manufacturing, installation and service, and undertakes standardized, automated and large-scale broiler, breeder, layer, pig farm projects and greenhouse temperature regulation projects with international advanced level.

In order to promote the production capacity and improve the logistics system, the enterprise specially invited our hospital to plan and build the automated warehouse for the new manufacturing center and R & D center project.

The automatic warehouse stacker is composed of mechanical structure (including upper and lower beams and columns), loading platform, running mechanism, lifting mechanism, fork telescopic mechanism and electric control device.

2. Speed regulation requirements for horizontal axis of stacker

Due to the particularity of the mechanical structure of the stacker, the bending moment of the loading platform and goods on the column, the horizontal inertial force produced by the acceleration and deceleration of the stacker will make the column produce deflection deformation in the roadway plane, affect the stability and reliability of the stacker, and make the debugging of the horizontal axis running speed and acceleration of the stacker more complex. The speed regulation of horizontal axis frequency converter should meet the requirements of stable acceleration process of the stacker, accurate parking with the shortest deceleration distance when the stacker reaches the maximum speed in a short time and runs to the destination address at high speed. The whole process of stacker operation should be reliable and stable. The performance parameters of the stacker: the maximum load is 1 000 kg, the maximum speed of the running shaft is 160 m / min, and the acceleration of the running shaft is 0.5 m / S2.

3 control system of stacker

The control system of the stacker adopts safesave-sn200g series PLC as the upper control, and the lower control is realized by the asynchronous motor driven by the frequency converter. The horizontal axis, vertical axis and fork operation of the stacker adopt the frequency converter to control the speed regulation of the asynchronous motor, and the position is located by the position value fed back by the laser ranging sensor, bar code locator and absolute value encoder.

3.1 network topology of control system

Through the PN / IE (PROFINET) network protocol, the PLC is connected with the frequency converter, encoder and laser ranging sensor. The frequency converter receives the start and stop command from the PLC through the field bus, and feeds back the online data current, voltage and motor running status of the frequency converter to the upper control system. In this project, the running signal of frequency converter is collected to PLC as the protection program to judge the complete stop of horizontal axis of stacker.

3.2 bus parameter configuration of frequency converter

After the hardware configuration of the stacker control system is completed, the input and output (I / O) configuration file of the inverter is matched with the input and output image area of the PLC. The output area of the PLC corresponds to the input area of the inverter, and the input area of the PLC corresponds to the output area of the inverter. The inverter receives frequency pulse speed regulation or speed regulation and feedback information by changing the parameter status word.

4 function of stacker control system

The horizontal axis speed regulation of the stacker control system is divided into manual operation speed regulation and automatic operation speed regulation. The manual speed regulation is used on the stacker to control the stacker to move forward at low speed, backward at low speed, forward at high speed and backward at high speed with the operating handle. A forced speed change switch is set on the ground to switch to low speed after the high-speed operation reaches the end of the roadway. Automatic speed regulation means that the stacker automatically accelerates from static state to high-speed operation according to the running distance after receiving the instructions of warehousing and outbound in online mode, and then decelerates to accurate parking after reaching the target location.

4.1 activate inverter bus control

Connect the inverter with somove software, open the DHCP function of the bus module of the inverter, open the supporting software, find the MAC address of the bus module of the inverter, and assign the written IP address to the inverter. After the address is assigned successfully, you can check the IP address information and monitor whether the parameters are wrong in the PROFINET setting interface of somove software. It should be noted that the equipment name and IP address are unique in the stacker control system.

4.2 configuration of Inverter Parameters

Use somove software to access the inverter online, quickly complete the basic parameter configuration according to the motor nameplate parameters, and carry out the static identification of motor parameters. After the optimization is completed, the first step is to jog the test, check the encoder, determine that the feedback parameters and the set speed are within a reasonable deviation, configure the encoder parameters, and change the open-loop operation to closed-loop control. Continue the inching test to ensure that the horizontal axis of the stacker does not vibrate under the manual low-speed control, and the operation process is stable. The output current, frequency and bus given frequency of the motor are collected by using the oscilloscope function of somove software, and the change of the value is monitored. The horizontal axis acceleration section, average speed section, deceleration section and parking precision section of the stacker are debugged.

Optimize the debugging of each stage to achieve the purpose of slow start, rapid acceleration, uniform speed, rapid deceleration and slow stop. The sn-200g frequency converter is selected, the user-defined ramp is used to match the whole operation mode, the ramp curve of acceleration and deceleration section is defined according to the operation condition, and the smooth proportion of the whole acceleration and deceleration stage is defined, so that the stacker has enough delay time (TA1) from the stop state to the acceleration stage to eliminate the inertia, and the end of delay will enter the acceleration section, When the acceleration section is to be completed, a smooth curve transition is made from the TA2 section to the constant speed section. When the constant speed section is switched to the deceleration section, a smooth curve transition is made from the TA3 section to avoid the impact caused by the sudden change of the stacker's speed. When the stacker slows down to the final stop, a smooth curve stop is made from the TA4 section to effectively reduce the impact caused by the large inertia when the stacker stops.

After setting up the ramp, the smooth and deceleration stop of the uniform speed section is debugged. By changing the proportional gain SPG, time constant SIT and filter coefficient SFC, the uniform speed section is stabilized. During the debugging, it is found that under the PID parameter operation with stable average speed, the horizontal axis is stable in the initial stage of start-up, uniform speed operation and deceleration, but the deceleration distance of the horizontal axis is longer. Under the same speed, the deceleration parking distance fluctuates greatly, and the deceleration is not enough in the final stage of parking. In order to solve this problem, by adjusting the speed loop PID parameters to improve the efficiency of horizontal axis speed regulation, to achieve accurate parking.

5 Application

The swing of the column of the stacker has a great relationship with the parameters of the horizontal axis speed regulation. If the horizontal axis speed regulation starts too fast or stops too hard, the swing range of the column of the stacker will be large, resulting in the cargo displacement of the loading platform and serious wear of the horizontal axis drive mechanism, reducing the safety of the stacker and shortening its service time. Therefore, after the completion of the speed regulation, it is necessary to ensure the stability of the horizontal axis speed regulation process of the stacker and meet the requirements of production efficiency. The application of sn200g vector converter friendly debugging software and its speed regulation stability can improve the speed regulation efficiency of horizontal axis and facilitate maintenance, which lays a good foundation for the later stable application.