North finder is a fast and high-precision autonomous directional instrument based on the strapdown inertial working principle. As a precision inertial instrument, the accuracy of north finder is related to the structure and installation of the sensitive components selected and the north-finding software. This article will mainly explain the software design of north finder.
1.Operation process of north-finding software
The essence of any software system is a data information processing system. The information that the system must process and the information that the system should generate determine the appearance of the system to a large extent. Therefore, analyzing the data requirements of the system is an important task of software requirements analysis. Combined with the actual needs of the north seeker work, according to the top-down software design structure analysis, Figure 1 can be obtained:
As shown in Figure 1, the north-seeking command comes from pressing the north-seeking start button on the control panel of north finder or from the north-finding start command transmitted from the RS422 serial port.When the computer receives this signal, the first process it performs is to give a driving signal. The north-seeking component brought by the driver moves to the starting position, and the sensor sends out a position signal (data).Then the computer processes the data, samples, samples and data pre-processes the gyroscope and accelerometer signals, starts the timer at the same time, determines the sampling period, and finally gives the sampling completion signal from the processed data, and stores the sampling results in D1. Similar to the previous processing, the computer operates the motor to rotate, sample, and store the sampling results in D2,...D5. The next process of the computer is the north-seeking calculation. After receiving the signal of completion of sampling, the CPU takes out the sampled data from D1..D5 for north-seeking calculation, and sends the calculation results to the display panel and communication port to complete the north-finding process.
2.Module design of north-finding software
Figure 1 only gives a rough description of the tasks and processes that the system needs to complete, but the data flow diagram is the basis of module design. Module design is divided into two stages: the first is system design, whose role is to determine the specific program of the system; the second is structural design, whose role is to determine the software structure. Here we mainly talk about the modular structure of the software, the specific functions of each module, and the mutual calling relationships between the modules.
2.1 Modular structure
We divide the program inside the north-finding system into several modules, and each module is set with a function. When these modules are gathered together to form a whole, the specified function can be completed, as shown in Figure 2. The advantage of this is that each module has independent functions and can be developed simultaneously by multiple people working together. Independent modules are easier to test and maintain.
2.2 Functions and calling relationships between modules
(1) Main module: After the computer is powered on or reset, the system initializes and waits for the arrival of the north search command. When the north search starts, the main module starts the motor positioning program to move the sensing head to the first position. After data collection , the motor rotates to the next position to continue sampling, and finally performs north seeking calculation and outputs the north seeking result.
(2) Input module: This is a command detection module, its task is to continuously detect the north search start command of the serial port and parallel port. When there is a request for north seeking, the information is sent to the main module to start the entire north seeking process.
(3) Motor positioning module: According to the requirements of the main module, this module controls the forward and reverse rotation and speed of the motor, detects whether the motor is rotated in place, and transmits the in-position information to the main module.
(4) Sampling module: It includes three sub-modules. Its function is to sample the output signals of gyroscope and accelerometer through A/D converter, preprocess the sampled data, and store the processing results in the memory. This includes Singular point deletion and filtering of sampled data, etc.
(5) North-finding calculation: After the transposition and sampling of the north-seeking instrument are completed, the data called by the main module is processed, and the result of the north-seeking calculation is returned to the main module.
(6) Output module: used to convert the north search results into serial data respectively. The serial data is installed in the agreed data format for data communication.
3. Summary
The above is our software analysis of the north-finding system. North-seeking software is the soul of north finder. Due to limitations in manufacturing technology and craftsmanship, improving hardware accuracy often requires a very high cost. After the hardware of the system is determined, the impact of software on its performance is crucial. The basic idea behind the design of north-seeking software is to use software to improve north-seeking accuracy on the premise of making full use of existing hardware resources. Ericco continues to optimize and develop in terms of inertial product accuracy. It not only has high-precision dynamic north seeker, but also low-cost north seeker suitable for customers with lower budgets, as well as MEMS three-axis north seeker. The products meet the needs of most customers. If you are interested, you can contact our professionals at any time.
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