CN102809961B - Solution for time varying and time slag problems of telescope control system - Google Patents
Solution for time varying and time slag problems of telescope control system Download PDFInfo
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- CN102809961B CN102809961B CN201210309250.4A CN201210309250A CN102809961B CN 102809961 B CN102809961 B CN 102809961B CN 201210309250 A CN201210309250 A CN 201210309250A CN 102809961 B CN102809961 B CN 102809961B
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Abstract
The invention discloses a solution for time varying and time slag problems of a telescope control system. According to the solution, an absolute time computation program is designed; a high-accuracy clock inside a universal motion and automation controller (UMAC) is employed; the absolute time computation program serves as a high-priority programmable logic controller (PLC) program or even a highest-priority PLC0 program and operates in the background of the UMAC; the PLC program or the PLC0 program acquires an initial value T0 of absolute time from a global positioning system (GPS) of an upper computer and acquires a current counting value t0 from the high-accuracy clock at the same time; a current counting value t is obtained by sampling the high-accuracy clock in any time, and current absolute time T can be obtained; the function characteristics are set by variables of parameters I; I10 sets servo interruption time, so the absolute time is obtained; a tracking data stream of the upper computer is obtained in the tracking process, and the tracking data stream comprises the absolute time information of a tracked object; and a UMAC motion program finds a target from the data stream according to the absolute time and tracks the target, so dependence on an upper computer clock and the influence of time slag in communication are eliminated, and the real-time performance and directing tracking accuracy of a telescope are greatly improved.
Description
Technical field
The present invention relates to a kind of control system time become the solution of Time Delay, while being specifically related to a kind of heavy caliber telescope control system, become the solution of Time Delay.The present invention is the achievement in research of state natural sciences fund general project (11073034) " research of the low temperature Nonlinear perturbations compensation in the tracking of South Pole heavy caliber astronomical optical telescope low-speed highly precise " (the common Funded Projects of Jiangsu Province " 333 " engineering).
Background technology
Time Delay is the problem that many control system all exist, and the performance that time lag can reduce control system even has influence on the stability of system.In telescope control system, also there is Time Delay.Time Delay is difficult to solve by conventional control algolithm.
It is very good that the control system of several the large-scale astronomical telescopes (as LAMOST) of Present Domestic adopts the mode of " IPC+UMAC+ independence high-performance servo-driver+independent servo force torque motor " this layering and distributed control to be proved to be effect.Hard real-time task is completed by UMAC, and host computer is only responsible for communication management, the weak real time tasks such as system maintenance and the calculating of celestial body track.Form each chief's of department working method.
UMAC is that general motion and automation controller (Universal Motion and Automation Controller) are that the multiaxial motion control product UMAC of Delta Tau company of the U.S. is the integrated PMAC of 3U framework, more be easy to expansion, function is also more powerful.UMAC motion controller has similar and PMAC programming language BASIC form, uses this Programming with Pascal Language, can make controller work alone.But the shortcoming of UMAC is that inner absolute time cannot be participated in computing.Its " DATE ", " TIME " only supply online order query display, and precision only can arrive second.Astronomical telescope is followed the tracks of celestial body, and higher to the accuracy requirement of time, while tracking taking azimuth axis, speed is as 15 "/s calculates, 10 milliseconds of time errors, bringing azimuth axis to point to tracking error is 0.15 ".Time lag in data exchange process has been brought huge puzzlement to telescope control accuracy.Because UMAC is at the clock that relies on industrial computer, rely on industrial computer and obtain current sensing target, send this target from industrial computer and carry out and follow the tracks of to UMAC, there is time lag.The tracking error that time lag has caused is along with the variation of tracking target speed changes.In addition, this time lag is subject to the impact of communication media, communication busy extent, operating system real-time in communication process, and self also changes time lag within the specific limits, becomes time lag while being individual.
As shown in Figure 1, this is a telescopical azimuth axis tracking data.Therefrom visible: with velocity variations, 19 minutes interior orientation axle tracking errors float to the interval of-1.2 "～-1.4 " gradually from the interval of-0.6 "～-0.8 ".Therefrom in visual data exchange time become the tremendous influence that time lag is brought to telescope tracking accuracy.
This time become Time Delay root be because UMAC does not have absolute time, cause telescope control system to have to rely on the time of upper industrial computer.Telescope control system does not also have good essence solution at present, can only alleviate by the real-time that improves communication and operating system.
Summary of the invention
The object of the invention is for the deficiencies in the prior art, while proposing a kind of telescope control system, become the solution of Time Delay.This method adopts the astronomical telescope tracking control system of UMAC controller, obtains reliable absolute time, thus solve telescope control system time become Time Delay, can greatly improve telescopical real-time and point to tracking accuracy.
Realize foregoing invention object technical scheme be: when a kind of telescope control system, become the solution of Time Delay, it is characterized in that, step is as follows:
(1). design an absolute time calculation procedure;
(2). this absolute time is calculated the high-precision clock (for example servo period counter) of Cheng Liyong UMAC inside; This absolute time calculation procedure as the PLC program (or PLC0 program) of a high priority at UMAC running background;
(3). this PLC program or PLC0 program obtain the initial value T of absolute time from the GPS of host computer
0, and the count value for example, obtaining now from high-precision clock (servo period counter) is t0 simultaneously;
(4). the functional characteristic of UMAC is by parameter I variable set up; Wherein I10 arranges the servo interrupt time;
The servo interrupt time
t swith the relation of I10 be:
（1），
Wherein 8388608 is 2
23;
The absolute time computing formula of random time is like this:
（2），
In formula (2), institute all calculate in seconds if having time, so further
tturn to the form of date Hour Minute Second, obtained the absolute time that we need;
(5). UMAC, in tracing process, obtains the streams of trace data from host computer, contains the absolute time information of tracked target in these data, and its information format is:
" absolute time azimuth axis object height axle target racemization axle target ";
Owing to obtaining current absolute time, UMAC motor program finds target to follow the tracks of according to absolute time in data stream; Thereby break away from the impact of time lag in dependence on host computer clock and communication.
Principle of work of the present invention, and the operation of more specifically more optimizing is:
There is high-precision clock UMAC inside, for example servo period counter.This clock/counter is 24 digit counters.Design an absolute time calculation procedure, utilized servo period counter, absolute time calculation procedure is as the PLC program of a high priority at UMAC running background, and the initial value of its absolute time is from the GPS of host computer.The PLC program of PMAC can repeat with very fast speed.Why be called PLC program, because these programs are carried out the function of similar hardware programmable logic controller.PLC control module is for the logic control of the switching value of system.When motor program is during in foreground orderly function, UMAC can be in nearly 32 asynchronous PLC programs of running background.PLC program can monitor the operations such as analog input and numeral input, order motion stop/starting with high sampling rate, with high rate of circulation, PLC program is scanned repeatedly.PLC0 is more special PLC program, be different from other PLC program in backstage circulation execution, PLC0 carries out on foreground together with servo algorithm, its priority is very high, so this program can not be too large, otherwise can take the time of servo algorithm, PLC0 is used for processing very high, the urgent task of requirement of real-time, we realize the calculating of absolute time with PLC0 herein, have guaranteed the accuracy of time.
PLC0 program obtains the initial value T of absolute time from the GPS of host computer
0, and the count value obtaining from servo period counter is now t0 simultaneously, random time so afterwards, it is t that sampling servo period counter obtains current count value, can be in the hope of absolute time T(shape now as date Hour Minute Second), wherein second with decimal, be accurate to 0.001 second.
The functional characteristic of UMAC is by parameter I variable set up.Wherein I10 arranges the servo interrupt time.
The servo interrupt time
t swith the relation of I10 be:
（1）
Wherein 8388608 is 2
23.
The absolute time computing formula of random time is like this:
（2）
In formula (2), institute all calculate in seconds if having time, so further
tturn to the form of date Hour Minute Second, obtained the absolute time that we need.Why be not all to get gps time from host computer at every turn, only read once when initialize, rely on PLC0 program oneself accumulative total later, exactly for fear of in dual-machine communication and exchanges data time become time lag.
UMAC, in tracing process, obtains the streams of trace data from host computer, contains the absolute time information of tracked target in these data, and its information format is:
" absolute time azimuth axis object height axle target racemization axle target "
Owing to obtaining current absolute time, UMAC motor program finds target to follow the tracks of according to absolute time in data stream.Thereby break away from the impact of time lag in dependence on host computer clock and communication.
The invention has the beneficial effects as follows that the present invention adopts the astronomical telescope tracking control system of UMAC controller to obtain reliable absolute time, thereby solved telescope control system time become Time Delay, greatly improved telescopical real-time and point to tracking accuracy.
Brief description of the drawings
Fig. 1 is that azimuth axis tracking error is with speed change curves figure;
Fig. 2 is absolute time PLC program variable watch circle;
Fig. 3 is the PLC program flow diagram that obtains absolute time;
Fig. 4 is Time Calculation program flow diagram.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described further.
There is servo period counter UMAC inside, and this is a high-precision clock.In UMAC, write following code:
#define ServoCounter M100 ; 24-bit servo cycle counter
ServoCounter->X:$000000,0,24,S
Make storage unit M100 point to servo period counter X:$ 000000,0,24, S, this clock/counter is 24 digit counters, each servo period increases by 1.Its counting, from UMAC powers on, can be turned to negative after counting down to maximal value.In the telescope control system of embodiment, the crystal oscillator frequency of UMAC is 19.6608MHz, systematic parameter I10=4194560, and the servo interrupt time of trying to achieve UMAC is
（3）
Be every increase by 1 in M100, representative increases by 500
.So just having obtained a resolution is 500
absolute clock.
Absolute time calculation procedure is as the PLC program of a high priority at UMAC running background, and the initial value of its absolute time, from GPS, is UMAC assignment by computing machine by Ethernet communication.
The PLC0 that employing has a limit priority obtains the work of absolute time.As shown in Figure 3, Time Calculation program flow diagram wherein as shown in Figure 4 for PLC0 program flow diagram.It is pointed out that Time Calculation program is not an independently subroutine herein, but a part in program, in order to clearly demonstrate the function of program, so independent especially.
Because servo period counter is 24 digit counters, the problem that has the maximal value of counting down to overturn, so program judges processing especially to this, its upset constant value is 2
23=8388608.
Obtaining after current time in seconds (being total number of seconds), following the tracks of the needs of controlling according to telescope, embodiment further turns to total number of seconds the form of date Hour Minute Second, and this is completed by Time Calculation program, as Fig. 4.
In process flow diagram, be integer second, and total number of seconds is with decimal place.Total number of seconds, within total minute, total hour, are all the absolute times when relative value to current count value adds UMAC start taking UMAC start as leading zero's.
In the time of the calculating of the time of carrying out, consider especially the computational problem in non-leap year and leap year.Herein by the following condition judgment leap year: can be divided exactly by 400; Can be divided exactly by 4, but can not be divided exactly by 100.
Just obtain astronomical telescope by above method and followed the tracks of the needed absolute time of celestial body, UMAC is in tracing process, obtain the streams of trace data from host computer, information format is " absolute time azimuth axis object height axle target racemization axle target ", owing to obtaining current absolute time, UMAC motor program finds target to follow the tracks of according to absolute time in data stream.
Fig. 2 host computer watch circle, has shown that the absolute time that in UMAC, PLC program is calculated changes, and proves that the method is correct, reliable.
Claims (4)
1. a solution that becomes Time Delay when telescope control system, is characterized in that, step is as follows:
(1). design an absolute time calculation procedure;
(2). this absolute time calculation procedure utilizes the high-precision clock of UMAC inside; This absolute time calculation procedure is as the PLC program of a high priority, or PLC0 program, at UMAC running background;
(3). this PLC program or PLC0 program obtain the initial value T of absolute time from the GPS of host computer
0, and the count value obtaining from high-precision clock is now t0 simultaneously; Random time afterwards, in the high-precision clock of sampling, obtaining current count value is t, can be in the hope of absolute time T now;
(4). the functional characteristic of UMAC is by parameter I variable set up; Wherein I10 arranges the servo interrupt time;
The servo interrupt time
t swith the relation of I10 be:
（1），
Wherein 8388608 is 2
23;
The absolute time computing formula of random time is like this:
（2），
In formula (2), institute all calculate in seconds if having time, further
tturn to the form of date Hour Minute Second, obtained the absolute time needing;
(5). UMAC, in tracing process, obtains the streams of trace data from host computer, contains the absolute time information of tracked target in these data, and its information format is:
" absolute time azimuth axis object height axle target racemization axle target ";
Owing to obtaining current absolute time, UMAC motor program finds target to follow the tracks of according to absolute time in data stream; Thereby break away from the impact of time lag in dependence on host computer clock and communication;
Step is the high precision clock of described UMAC inside (1), is to adopt the servo period counter of 24.
2. the solution that becomes Time Delay when telescope control system according to claim 1, is characterized in that, (2) step writes following code in described UMAC:
#define ServoCounter M100 ; 24-bit servo cycle counter
ServoCounter->X:$000000,0,24,S
Make storage unit M100 point to servo period counter X:$ 000000,0,24, S.
3. the solution that becomes Time Delay when telescope control system according to claim 1, is characterized in that, (3) described " trying to achieve absolute time T now " of step, wherein second with decimal, is accurate to 0.001 second.
4. during according to telescope control system one of claim 1-3 Suo Shu, become the solution of Time Delay, it is characterized in that, in telescope control system, the crystal oscillator frequency of UMAC is 19.6608MHz, systematic parameter I10=4194560, the servo interrupt time of trying to achieve UMAC is
（3）。
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| CN201210309250.4A CN102809961B (en) | 2012-08-27 | 2012-08-27 | Solution for time varying and time slag problems of telescope control system |
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| CN102809961B true CN102809961B (en) | 2014-09-17 |
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Citations (4)
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| EP1337058A2 (en) * | 2002-02-19 | 2003-08-20 | eRide, Inc. | Method and system for distributing absolute time in a GPS receiver network |
| CN101047434A (en) * | 2007-04-10 | 2007-10-03 | 华为技术有限公司 | Time tag synchronous method, system and device |
| CN101060425A (en) * | 2006-04-21 | 2007-10-24 | 大唐移动通信设备有限公司 | Absolute time data acquiring method and system |
| CN101739731A (en) * | 2009-11-20 | 2010-06-16 | 佛山市艾科电子工程有限公司 | Distributed time measurement method for each measuring point and distributed time measurement system |
Family Cites Families (2)
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|---|---|---|---|---|
| US7139225B2 (en) * | 2003-03-27 | 2006-11-21 | Qualcomm, Incorporated | Virtual real-time clock based on time information from multiple communication systems |
| US8035558B2 (en) * | 2008-05-30 | 2011-10-11 | The Boeing Company | Precise absolute time transfer from a satellite system |
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2012
- 2012-08-27 CN CN201210309250.4A patent/CN102809961B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1337058A2 (en) * | 2002-02-19 | 2003-08-20 | eRide, Inc. | Method and system for distributing absolute time in a GPS receiver network |
| CN101060425A (en) * | 2006-04-21 | 2007-10-24 | 大唐移动通信设备有限公司 | Absolute time data acquiring method and system |
| CN101047434A (en) * | 2007-04-10 | 2007-10-03 | 华为技术有限公司 | Time tag synchronous method, system and device |
| CN101739731A (en) * | 2009-11-20 | 2010-06-16 | 佛山市艾科电子工程有限公司 | Distributed time measurement method for each measuring point and distributed time measurement system |
Non-Patent Citations (2)
| Title |
|---|
| 基于 UMAC的精密伺服控制系统;徐欣圻等;《安徽大学学报》;20050731;第29卷(第4期);全文 * |
| 徐欣圻等.基于 UMAC的精密伺服控制系统.《安徽大学学报》.2005,第29卷(第4期),全文. |
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Granted publication date: 20140917 Termination date: 20180827 |