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The mine pit elevator measured precisely the fast microcomputer realizes
The mine pit elevator is the mine pit production important equipment, the load mineral, the material, the equipment and the personnel moves back and forth transportation's duty in the well chamber, holds the extremely important position in the mine pit regular production. Moves reliably safely for the guarantee lift technique, the request control system's performance is good, must have the high velocity modulation performance and the position control.
Along with the computer applied science's swift development, uses the computer control system substitution original electrically controlled system is one tendency. As a result of the mine pit elevator control system highly complexity and to the security reliable strict request, domestic has not developed at present is more ideal, is suitable for the industry scene request the computer control system. This article introduced the author is engaged in a piece which this aspect works.
1 To the microcomputer measured that the fast installment request
To the microcomputer measured the fast installment the general request is: Resolution is strong, the precision is high, as far as possible short examination time.
1.1 resolution
When carries on the rotational speed examination with the microcomputer, the resolution with changes was measured that the rotational speed which a survey meter digit corresponds the change quantity expressed. Supposes the rotational speed when become n2 by n1 causes the survey meter value to change a character, represents the resolution with Q:
The resolution size and system's control precision relations are really big, the Q value is smaller, resolution is stronger, system's control precision is higher, it is measures the fast installment an important target.
1.2 measured that fast precision
Measured the fast precision is refers to measures the fast installment to the actual tachometric survey precise degree. If with △n represents the observed value and the actual value difference, n represents the actual rotational speed, ε% represent the measuring error which expressed with the relative value, then
Obviously, ε% is smaller, measured that the fast precision is higher; system's control precision will be also higher. The measuring error ε% sizes decided that in measured the fast part's manufacture precision, and with measured the fast method concerns.
1.3 examination time
The examination time is refers to between two time rotational speed sampling the time-gap. The examination time's length the control performance influence is very big to the system, if the examination time is very long, then the system will realize the stable fast response with difficulty. The examination time is shorter, is more advantageous regarding system's control performance's improvement.
2 The microcomputer measured that fast general method
By the electro-optical type revolving encoder and elevator's axis solid joint, the elevator retransmits the certain amount every time (1080) the signal impulse, takes down the pulse number by the counter, and gives computer processing to realize the microcomputer to measure fast. Commonly used measured that the fast method mainly has the following two kinds.
2.1 The M law measures fast
The M law measured that fast is reads the pulse integer which in the equal time-gap the revolving encoder sends out to figure out the rotational speed. The pulse number which sends out in the same time internal rotation encoder is different; the observed value is not same. The M law measured that fast schematic diagram as shown in Figure 1.
By the counter the pulse counting which transmits to the revolving encoder, timer every other time T sends out an interrupt request to CPU, extracts corresponding according to the counting value's size the rotational speed. The revolving encoder retransmits pulse 1080 every time, altogether has m pulse in the T time, then the rotational speed is:
This kind measured that the fast method is by the counting value m size reflection rotational speed height, thus is called the M law to measure fast.
(1) Resolution
May result in according to the resolution definition by type (3):
Obviously, the M law measured fast when the resolution has nothing to do with the speed size, concerns with rotational speed sampling period T.
(2) measured that fast precision
When measures using the revolving encoder fast, its measuring error decided that concerns in encoder's manufacture precision and with the rotational speed size. Supposes between the revolving encoder two neighboring pulses the angular deviations are. εp%, an examination cycle's counting value is m, then the measuring error is:
The rotational speed is lower, m is smaller, the measuring error is bigger, measured that the fast precision is lower. Along with the RPM drop measured that the fast precision reduces is the M law measures a fast shortcoming.
(3) Examines the time: Is equal to survey cycle T.
2. 2 T law measured that fast
T law measured fast is determines between the revolving encoder two output pulses the time interval to calculate the rotational speed to measure the fast method. The time survey carries on the counting by a counter to the known frequency's clock pulse to obtain, the T law measured that fast schematic diagram as shown in Figure 2.
The revolving encoder outputs a pulse through the microcomputer connection sends out an interrupt to CPU, after the CPU response, to read out the counting value every time from the counter, then figures out the rotational speed by the counting value. Supposes the clock rate is f, counting values between two pulse's are m, then rotational speed n is:
May see, the T law measured that fast is just the opposite with the M law. Rotational speed higher survey meter value m is smaller.
(1) Resolution
Supposes, because the rotational speed counting value becomes m-1 by m, according to resolution definition:
By type (7), Q value size and rotational speed related, the rotational speed is smaller, m is bigger, Q is smaller, measured that the fast installment resolution is stronger. The T law measured that the fast merit lies in the low speed section to have the strong resolution to the rotational speed, thus may enhance the low speed the control performance.
(2) Measures the fast precision
Measuring error is equal to the angular deviations between the revolving encoder two pulses εp %, namely measuring error:
It only decided that in encoder's manufacture precision, with is measured the rotational speed to have nothing to do with, it compared to the M law measured that the fast precision must miss.
(3) examines the time:
Because the revolving encoder retransmits 1080 pulses every time, therefore between two pulse's time intervals are:
Type (9) indicated that the T law measured the fast examination time changes along with the rotational speed.
3 Mine pit elevator to tachometric survey's request
The mine pit elevator's movement process is a periodic process. Generally elevator's promotion cycle including the acceleration, the constant speed, the deceleration, crawling, stops five stages. In five stages, elevator's running rate has the very wide difference. Below gives the AnhuiProvince some ore elevator movement the speed chart, see Figure 3. May see by the speed chart, in the acceleration leg and the deceleration section elevator's speed is one process which changes unceasingly according to certain acceleration or the retarded velocity, constant speed Duan Yijiao the high running rate movement, the crawling section speed relative says must be much slower, only then 0.4m/s, generally speaking, the elevator movement process is a speed the process which changes unceasingly in the wide range, if wants to realize the microcomputer to measure accurately fast, then measured that the fast method must satisfy in the high speed and compares the low speed section to be able the correct measurement request.
In order to safeguard the elevator movement the high security, in elevator's each kind of protection, has the constant speed section too fast protection and the deceleration section too fast protection, the constant speed section running rate like surpasses highest rotational speed Vm 15%, elevator safety arrestment; In deceleration section movement, if determines the speed to surpass given value 10%, also will implement the safety arrestment. Therefore, to reflect in the elevator movement accurately the speed condition, realizes the control system security, reliably, to move continuously, requests the speed which the microcomputer determines to be accurate, can satisfy certain precision.
4 The elevator measured precisely fast M/T law
By above may know, elevator's velocity measurement request has the high precision, can reflect in the elevator movement accurately the actual rotational speed. The fore-mentioned M law measures fast, low speed Duan Cesu the precision is quite low; The T law measures fast, low speed section rotational speed resolution is strong, but it measured that the fast precision is also much worse than the M law, they use in the elevator measuring the fast insufficient ideal; But M/T measured that the fast principle synthesizes two methods the merits, both may the low speed section reliable surveying fast, and also has the high resolution in the high speed section, adapted the elevator to the velocity measurement request. The M /T principle measured that the fast principle sees Figure 4.
And T0 by a timer fixed time, examination cycle T had finished after T0, the pulse generator output's first pulse decided that namely T=T0+△T, m1 is the pulse number which in the T time the encoder sends out, m2 is in cyclical T to the clock pulse counting value. The rotational speed expression is:
A in the formula f clock pulse frequency; the 1080yi encoder retransmits every time pulse number.
We develop in the IPC control system, the M /T law measured that fast is relies on the HY-6220 counting/timer template realizes, this is IBM PC the XT/AT main line compatible isolation type programmable multi-purpose template, on the board has 8253,8255,8259 three kind of programmable components. The M/T law measured that the fast hardware realizes the chart to see Figure 5.
The work process is as follows: The computer sends out the start signal, outputs the first pulse from the encoder, 8253 timer (T0) counting start, 8253 counters (m2) also starts to count at the same time, after 20ms, the T0 timer to 8259 round of signals of stop, sends a pulse again until the encoder, stops m1 and the m2 counter, and through 8259 sends out the interrupt request to CPU, computation rotational speed n.
The HY-6220 template software programming diagram see Figure 6.above
Gives the M/T law to measure that the fast hardware realizes the chart and the software diagram, presently discusses the M /T law to measure questions and so on fast resolution.
(1) Resolution:
M/T law velocity meter value m1 and m2 change along with the rotational speed. In this separately to high speed section and low speed section discussion resolution. In the high speed section, T0≥△T, namely T≈T0, thinks M2 not along with the rotational speed change. In this kind of situation may result in:
The M2= fT≈fT0 substitution above equation: Q=60/1080T0. This with the M law measured that the fast resolution is completely same. When the rotational speed is very low, m1=l, m2 changes along with the rotational speed change, its resolution is:
This measures with the T law fast identical.
Figure 6 HY-6220 template software programming diagram analyzes by on, the M/T law measured that fast the law is close in high speed Duan Yum, is close in low speed Duan Ze and the T law, has at the same time the two's merit, has the strong resolution in high speed and the low speed.
(2) Measures the fast precision:
The high speed section (M1>1), measured that the fast precision and the M law are the same, namely ε%=εp %/m1; in low speed section (m1
(3) Examination time:
The M/T law measured that fast examination cycle T under the different rotational speed is different, (m1>1) and the M law is close in the high speed section, the rotational speed is higher, examination time closer T0, in low speed section is close with the T law.
5 conclusions
The M/T law measured that the fast microcomputer realized, has satisfied the elevator movement to the velocity measurement request, in the constant speed section, the deceleration section and crawled Duan Junneng to satisfy certain accuracy requirement, had guaranteed the elevator safe, reliable, moved continually.