Chapter 669: Wait for your comrade
Having said this, Mr. Mo pointed to a component in the plan: "But the adjustment effect of this piezoelectric component has never been ideal. At first, we thought that the input and output characteristics of the piezoelectric component were not good and the output could not be accurate."
Piezoelectric elements, simply put, precisely control the deformation of the active surface of the element according to the input voltage.
The most common piezoelectric component is the piezoelectric ceramic buzzer, which controls the vibration of the buzzer according to the voltage and emits a buzzing sound.
It can be seen from this point that the control speed of piezoelectric elements is fast. After all, if people want to be able to hear, at least the vibration frequency of piezoelectric elements must be above 3k, which is 3,000 times per second.
But when the control goal changes from deformation frequency to precise control of deformation amplitude, things change.
The voltage input and deformation output must be an accurately corresponding relationship line. Otherwise, with the same voltage of 1V, the deformation this time is 1mm and the next time it is 1.2mm, which would become a fantasy for the optical cavity length control of the laser gyroscope.
"So we found the manufacturer of piezoelectric components and worked together to solve the problem of the input and output characteristics of the piezoelectric ceramics."
Upon hearing the news, Gao Zhendong slapped his thigh: "Well done!"
Startled by Gao Zhendong's sudden excitement, Mr. Mo reacted with a wry smile: "The comrades in the production plant who cooperate with us are indeed good, but we are not very good. After the input and output characteristics problem was solved, we discovered that, The biggest problem is not only this problem, but also that we cannot accurately control the output voltage. If the voltage is inaccurate, the natural deformation will be inaccurate, and the length of the optical resonant cavity will be bad.”
The wavelength of the laser is not that big. Correspondingly, the length adjustment of the optical resonant cavity is extremely small, which is why piezoelectric elements are used for adjustment and control.
This means that a sufficiently accurate output voltage is required to adjust the cavity length to an acceptable level.
"We have tried many methods, but the resolution of the output voltage has never been ideal. We thought, Mr. Gao, you are also very proficient in electronics, so we came to you to see if there is any way."< br>
Mr. Mo is also very magnanimous. He is desperate, so he comes to you. He is looking for the inventor of the laser. He is not shabby.
Gao Zhendong thought about it, you really did the right thing to ask me about this matter.
"What voltage resolution can you achieve now? How many people are there?"
"We have solved the problem of high-precision voltage source...but the resolution is only 6 bits and can no longer be improved."
To output a precise and adjustable voltage, two conditions are essential. One is a high-precision voltage source as the reference voltage, which determines the accuracy of the voltage. Otherwise, if you want 5V, the output is 5.1V.
The other one is D/A with sufficient resolution, which determines the output resolution.
The often mentioned accuracy actually includes two aspects, precision and accuracy. The former is the degree of fineness, that is, the resolution, and the latter is the degree of accuracy, that is, the accuracy.
Now they've solved the problem of accuracy, but there's still an issue with finesse.
With a high-accuracy voltage source, its output characteristics are certain. It does not mean that by reducing the voltage through the secondary circuit, a more practical resolution can be obtained when the number of resolution bits is insufficient. The buck circuit will introduce new errors, and this also means that the controllable range becomes smaller.
Therefore, high-resolution D/A is still required.
The 6 bits mentioned by Mr. Mo mean that a voltage can only be divided into 64 parts for control at most, which is indeed a bit low.
However, the original research institute is really powerful and has solved all the problems that can be solved. The last one who had no choice came to Gao Zhendong.
This is easy to handle. Gao Zhendong smiled and said: "This is easy to handle. Is 8-bit accuracy enough?"
"8 digits? That's enough!" Mr. Mo was very happy. Chief Engineer Gao directly asked "is 8 digits enough" instead of "how many", which meant that Chief Engineer Gao had at least 8 digits of D/ A, or related technology.
Don't look at 6 digits to 8 digits, the number has only increased by 2 digits. In fact, the number of levels that divide the voltage has been increased from 64 to 256.
Gao Zhendong was happy: "You go to the Military Communications Institute, which is building an 8-bit weighted network decoder. It was originally used for speech encoding, but basically it is an 8-bit analog-to-analog converter. You go Take a look, it should be usable. If the number of bits is not enough, this kind of device is easier to expand. If 8-bit is not possible, then 10-bit. If 10-bit is not possible, then 12-bit... Anyway, your requirements for conversion speed are not particularly high. "
Is there such a good thing? Mr. Mo was extremely happy.
"Really? Haha, great, great, great. We will go back to the National Defense Work Committee to ask for permission."
After speaking, he raised his head and said: "General Engineer Gao, you don't know. You have solved half of our other problem at once."
The comrades at the original research institute are very interesting. They know all the problems, but they can't solve them. This is true for optical cavity length control, and so is the frequency locking problem.
"Frequency blocking uses dither offset frequency. As you said last time, dither offset frequency seems simple, but how to dither is a practical engineering problem. Our problem now is that we cannot accurately control the dither frequency."
Mr. Mo was very happy and talked more.
"The current situation is that the frequency and amplitude of this jitter cannot be controlled very well. As a result, the compensation value of the compensation part in the frequency locking area deviates greatly from the theoretical value." "We have also analyzed it. Now The main problems that can be seen are that the conversion accuracy from digital to analog is not enough, and the jitter control device is not good enough to realize our control function in this volume.”
Due to processing problems, the consistency between devices is not very good. Even if it is theoretically possible to use fixed optimal parameters for dithering, in fact the parameters of each gyroscope are still slightly different.
Gao Zhendong understood as soon as he heard that the jitter frequency still needed to be digitally controlled, and the most troublesome thing about digital control for them was the control core and the digital-to-analog conversion.
After all, the core volume of a single unit of this thing is not large. The scale of more than ten centimeters is mainly occupied by optical components. The external control system cannot be too large, otherwise half of its meaning will be lost.
The D/A device that Gao Zhendong just directed them to get can also solve half of the problems of this mechanical jitter bias system, which is why Mo Gong is so happy.
In this way, even if the remaining problems cannot be solved, at worst, it will still be usable by hanging an extra DJS-60D. Although the advantage of small size is gone, at least the other advantages are still retained, so it is not a loss.
But right away, Gao Zhendong told him what true compensation looked like.
"As for the core issue of control, I see this plan. In fact, the control does not require high computing power and speed. It just needs to have flexible enough control methods to take into account the calculation and output of data, right?"
< br>
"Well, yes, yes, on this basis, the higher the output refresh rate, the better."
Under the premise of ensuring accuracy, the higher the data refresh rate, the better. For advanced gyro data users, this is equivalent to greatly increasing the sampling frequency, which means that the error will be smaller.
"Hmm... In this way, you can use DJS-61 to deal with the problem of controlling the core first."
"DJS-61? How small is this?"
They naturally know about C6108 and DJS-61, but they have no intuitive feeling about how small these things are. Especially the DJS-61, as shown in the photo, it also comes with a chassis including a power supply.
Gao Zhendong didn't say much, turned around and opened a drawer, took out three DJS-61 motherboards and handed them to Mr. Mo.
Then, with everyone's stunned expressions, he opened another drawer, took out the matching quantity of C6108 and C6110, and handed it to them.
"You can use these first, are they enough?"
"That's enough, Mr. Gao, that's all the DJS-61 is?" In fact, the other half of what he said was, why are you just putting away scratch paper for such an expensive thing?
Gao Zhendong nodded: "Yes, this thing is only so big, but don't underestimate it, this thing is at least 2.5 times faster than the DJS-60D!"
Only then did Mr. Mo remember that in reports about the DJS-61, it was indeed mentioned that this machine was much faster than the DJS-60D, but the specific speed was not mentioned.
Mr. Mo calculated it in his mind, haha...
"If this is the case, we won't need three DJS-60Ds. One will be enough."
A complete gyroscope requires three laser gyroscopes to measure the rotation in three-dimensional space. At the speed of DJS-60D, a computer is required to serve each one to provide a sufficient data refresh rate. That's it. There is no way to take into account the control of mechanical jitter and offset frequency.
The size of three DJS-60Ds is still too large compared to the laser gyroscope.
But now that Chief Engineer Gao has come up with this thing, one machine can take care of the data calculation, refresh and various controls of a laser gyroscope.
In this way, three DJS-61s can accomplish what three DJS-60Ds cannot. More importantly, the sum of the three DJS-61s is not as big as the one of the latter!
This is of great significance for the practical use of laser gyroscopes.
"Hey, Mr. Gao, then we are not polite. Then whoever, put it away, put it away."
Mr. Mo's expression at this time was very similar to the way we used to shirk the New Year's money from our elders when we were children.
"You guys can use it first. There are some new things being developed here. Maybe by next year, you will be able to use smaller devices."
Gao Zhendong's words caused Mr. Mo and others to fall into deep self-doubt.
No, I haven’t finished a single thing here yet. Why do you seem to be making new things for free and without spending time? One after another, there are too many.
This made Mr. Mo even fall into a kind of happy trouble. How about we wait? Otherwise, the system connection and installation design will have to be changed, and even the program will have to be significantly changed, which will be very troublesome.
Chief Engineer Gao, please stop your steps and wait for your comrades!
(End of chapter)