Control System Design of Automatic Feeding Machine
Shaoke Chen 1, 2
1 Mechatronic Engineering Department, Shantou University, Guangdong, 515063 China
2 Shantou Institute for Light Industrial Equipment Research, Guangdong, 515063 China
E-mail: [email protected]
Keywords: fixed-time, fixed-quantity, feeding machine
Abstract. The research of the control system of automatic feeding machine in the present paper can
be applied in different mechanical designs – from simple key-press input of cycling days, multiple
time intervals and the feeding amount to setting steps of numbers of stepping motor via the control
of SMC by time setting. This not only realizes the objective of “fixed-time” and “fixed-quantity”
feeding, but also solves the problems of serious leaking, high failure rate, and loud noises during the
process of using warehouse-type feeding machines, which brings favorable economic and social
benefits for enterprises.
Introduction
With the expansion of the scale of social production, people set higher requirement for
mechanical automatic production. Traditional machines will inevitably be eliminated. Unmanned
operation or automatic production with as little manual work as possible will take the place of
traditional machines. The improvement of traditional machines or the development of new
intelligent machines is the developing direction of current machinery industry. The automatic
feeding machine combines transportation, weight measurement and fixed-quantity control together,
which belongs to high-tech product with electromechanical integration. The machine can adapt to
all kinds of industrial production environments, including continuous feeding measurement of
power/ grain/ lump-shaped granular material, and it is widely used in different industrial production
sectors, such as building materials, metallurgy, electricity, chemical engineering, and light industry,
etc.[1]
Based on the application of non-large-scale production, the present design aims at designing for
the electrical control system of automatic feeding machine. Because high manufacturing cost is a
disadvantage in market competition, the design should take its cost into consideration. The design
should follow two principles: practical and simple. According to actual situation and user demands,
no matter mechanical structure or circuit hardware should be as simple as possible. The objectives
of keeping simple are two: one is improving machine reliability; second is reducing production cost.
The designing development of the electrical control system of automatic feeding machine is
favorable to the improvement of working efficiency of the feeding machine, decrease of manual
intervention, economization of manpower, and promotion of large-scale production. [2]
System Design
Based on the task analysis of the electrical control system of automatic feeding machine, the
system realizes the design of hardware and software. The former includes the configuration of
master device, functional module, and detailed design of schematic circuit diagram; the latter
Applied Mechanics and Materials Vols. 157-158 (2012) pp 466-471Online available since 2012/Feb/27 at www.scientific.net© (2012) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMM.157-158.466
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,www.ttp.net. (ID: 130.236.84.134, Linköpings Universitet, Linköping, Sweden-18/08/14,13:11:00)
designs for the program structure of the overall controlling system based on modular programming
ideas. The software can write modular programs, such as initialization, manual drive, automatic
drive, numerical calculation, data communications and monitoring, etc. The human-computer
interface of the design system can realize the interaction between users and the system. [3]
The overall schematic diagram of the feeding machine is shown in Figure 1. The storage box
stores feeding materials. The impeller hopper consists of several blades and the space between
every two blades is fixed. The impeller hopper is driven by the stepping motor. Timing control of
the rolling angle of the stepping motor can control the number of space for blade hopper rotation
and therefore realize quantitative control of the feeding amount.
Fig. 1 Overall Schematic Diagram of the Feeding Machine
The feeding amount can reach a fixed quantity every time the feeding machine works. Users can
set the required amount according to the real situation and their own will. Within each cycle
working time for starting the machine, one unit of feeding amount is enough. In the control segment,
the feeding machine can calculate and thus obtain the rotating angle and make sure the export of
feeding machine according to fixed demand and set time. At the same time, users should check
whether the feeding box is lack of feeding materials. If yes, the machine will give an alarm and stop
feeding.
Design of Hardware System
The electrical control system design of the present feeding machine can meet the requirement of
timed and fixed-quantity feeding from the aspects of both software and hardware. According to
different mechanical structures and via the change of procedure parameter (such as the conversion
set of feeding amount and the display setting of menu), the design can adapt to the timed and
fixed-quantity feeding of different objects. Control of the stepping motor can be realized via parallel
mode and thus achieve the goal of controlling multiple stepping motors of the same type and
realizing large-scale production. [4]
The feeding machine has three main functions, namely “timing”, “fixed quantity” and
“automatic feeding”. The design of its electrical control system is based on these three main
functions. Furthermore, the development of the electrical control system of the feeding machine is
mainly based on the AT89S51 SCM chip, the program of which is written by C Language and
displayed on the LCD Screen. After confirming the input, time counting starts. This system is
divided into three main parts:
Applied Mechanics and Materials Vols. 157-158 467
(1) Input and Display Part: Via high-and-low PWL judging method, four keys can be set,
namely “plus”, “minus”, “enter” and “return”. They can be displayed on the LCD1602A Screen.
(2) Time Accumulation Part: The time starts from “0” using the time accumulation method with
the minimum digit of 0.1 second and displays on the LCD1602A Screen.
(3) Quantitative Feeding Part of the Stepping Motor: Once the accumulated time has reached the
set time, the accumulator will stop working. After the SCM (Single-Chip Microcomputer) reads the
feeding amount set by the program, it will start the stepping motor and make it rotate corresponding
angle or rounds, and thus achieve certain feeding amount.
The control system mainly involves SCM design, including displaying operation signal
interface, etc. The SCM is the control core of the overall system and completes all monitoring
functions. The reason of choosing AT89S52 SCM is because it has advantages like rich hardware
resources, strong processing ability, fast operation velocity, and low power consumption, etc.
Besides, it makes development, debugging and application more flexible and convenient. The
design diagram of the hardware system is shown in Figure 2. [5]
Fig. 2 Design Diagram of the Hardware System
The stepping motor is controlled by the SCM. However, the controlling system cannot drive the
charged component directly. It needs the power circuit to expand and export the electric current so
as to meet the demand of electric current and voltage of the charged component. The series product
of ULN2XXXX High-voltage & Strong-current Darlington Transistor Array belongs to this kind of
controllable high-power device. Because of its great function and wide field of application, the
ULN2003A chip is chosen as the driver.
Design of Software System
The system has the functions of setting and changing parameter. Control modes, feeding amount,
upper and lower limits can be set online; feeding amount, limit value of alarm, and mechanical
parameter of the system can also be changed online. The program design can be divided into three
parts: first part is the input and display of menu design, time interval, input and display of the
feeding amount; second part is time accumulation and its display; third part is the driving motion of
the stepping motor and the control of its rotating rounds, angles, and velocity, etc. The flow chart of
menu input is shown in Figure 3. [6]
468 Mechatronics and Applied Mechanics
Fig. 3 Menu Input Flow Chart
The section of data input contains 4 parts, namely the input of the number of days (D), input of
initial time interval t0, input of No.1-4 time intervals t1~t4, input of feeding amount (G).
Input of the number of days (D): First line on the LCD1602 shows the sample “Days input:
(D)”; the first and second spaces in the second line can be filled in with a two-digit number of days,
the data range of which is from “00~31” days. The data can be entered via a “while” cycle criterion.
K1 means data plus 1; K2 means data minus 1; K3 is confirmation and switch to the next menu (t0
means entering the menu). The input of time t0~t4: it is the same as the input method of the number
of days (D), except changing the menu requires one more key, K4. The function of K4 is return to
the previous menu, which can be used when you mistakenly enter the next menu because of
modification, incorrect input or sensitivity of the press button.
Input of feeding amount: It slightly differs from the time input because the feeding amount
displayed is a 4-digit letter. The display of the input shows the last four digits, with a unit “g”. The
maximum number of input is 5000g. The key functions are consistent. However, the “+” button
written on the program means adding 50g of feeding materials each time, that is, the division value
is 50g.
In order to get a visualized view of each input amount on the screen and make full use of the
LCD1602 resources, the second line of each input amount is kept on the screen. When you enter the
next menu, the input amount does not clear the screen. Therefore, the writing of each data is
allocated to different addresses, from 0xc0 to 0xcf respectively. This is why every cycle of menu
program has to write the program for LCD individually, instead of using a common function.
The section of time accumulation is the core of the overall program because it involves time
setting and how to control the stepping motor. Its flow chart of time control is shown in Figure 4.
Applied Mechanics and Materials Vols. 157-158 469
Fig. 4 Time Control Flow Chart
After entering the “while” cycle, the time is accumulated by a unit of 0.1s. When it first reaches
t0, time accumulation stops. Then the procedure turns to the subprogram of the start-up of the
stepping motor and control quantitative feeding. Once the feeding completes, the time accumulator
will be reset and use “if” sentence to judge whether t1 is 0. If not, the number of days will be
subtracted by 1 after the time accumulates to 24 hours. Then the program goes to the subprogram of
controlling feeding materials and enters the cycle.
If t1 is not 0, use “go to” sentence and turn to “run1”. The function of “run1” is to start from 0
and re-accumulate time. Control the feeding amount when the time accumulated reaches T=t1.
Similarly, once feeding completes, use “if” conditional statement to judge t2. T2 means 0 to run5.
Otherwise, 0 turns to run2. The function of run2 is slightly different from run1. The reason is that
the time accumulator keeps accumulating on the basis of the original time, without resetting. When
the time accumulated reaches T=t1+t2, the subprogram is applied to quantitative feeding. The
functions of run3 and run4 are basically consistent with run2, except the value of accumulator T is
the total accumulation time without t0.
No matter the section of t0 timing or the section of t1~t4 timing is applied, the same “while”
statement is used to cycle the subprogram of 0.1s delay. The variable of the time accumulator t0_1
should be compared to tn (n=0;1;2;3;4) to realize the function of time setting. Therefore, when the
time accumulates to t0_1=10, the result of time accumulation is no longer 10s, but 1s. Before tn
enters the program and compares with t0_1, it should be changed into the same unit as t0_1.
Users can observe the procedure parameter and status required from the on-the-spot controlling
board. The setting of feeding amount and limit values, direct modification and setting of controlling
parameter, start and cessation of the system equipment, the switchover of different working modes,
etc. can be completed.
470 Mechatronics and Applied Mechanics
Summary
Through the installation and site debugging of the automatic feeding machine and electricity, it
shows that the present system works steadily and realizes all expected functions. The on-the-spot
application demonstrates it has a positive meaning towards improving production efficiency and
guaranteeing product quality, which achieves a better result. The machine has a better calculating
ability, controlling performance and high practical engineering value. Meanwhile, it reduces the
construction costs, which enhances the performance price ratio of the system.
Acknowledgement
The authors wish to thank the Natural Technology Innovation Fund of Technology-based SMEs
(Small and Medium-sized Enterprises), P. R. China for providing a grant (No:11C26214403131)
and the Co-operation of Industry-University-Research Institute, Guangdong Province & Ministry of
Education, P. R. China for providing a grant (No:2009B090300175) for this project.
References
[1] Altintas Y., Verl A., Brecher C., Uriarte L., Pritschow G.: Machine tool feed drives, CIRP Annals
- Manufacturing Technology, v60(02), p779-796. (2011)
[2] Guan Li-Ming, Lin Jian: Synchronization control of sheet feeding machine of shaft-less drives,
Control Theory and Applications, v26(05), p573-577. (2009)
[3] CAO Luo-sheng: Design and research on domestic electrical appliance timing system, Applied
Science and Technology, v34(07), p11-13. (2007)
[4] HONG Yuan: Deisgn of intelligent time control system base on Single-Chip Microcomputer,
Journal of Henan Vocation-technical Teachers College, v33(01), p97-98. (2005)
[5] Wang Weimin, Wang Jian, Shao Changan: Accurate Quantitative Control in Batch Feeding
Control System, Process Automation Instrumentation, v30(07), p55-57. (2009)
[6] Wang Xiaoyuan, Li Juan: High performance quantitative control system, Electronic
Measurement Technology, v29(06), p69-70. (2006)
Applied Mechanics and Materials Vols. 157-158 471
Mechatronics and Applied Mechanics 10.4028/www.scientific.net/AMM.157-158 Control System Design of Automatic Feeding Machine 10.4028/www.scientific.net/AMM.157-158.466