With the approaching of the 2008 Beijing Olympic Games, sailing has attracted more and more attention. It is particularly important to use modern scientific and technological means to assist training to improve the performance of the competition. Considering the real-time collection of data on the field to guide training and to reduce the work intensity of sailing coaches, the design of the sailing attitude instrument enables coaches to understand the specific training details of each athlete and improves work efficiency.
1. System design of sailing attitude instrument
The sailboat attitude instrument designed based on PIC16F877A can collect the pitch angle, left and right swing angle, mast rotation angle and GPS system to record the sailing trajectory during the sailing process. The system records the collected data once every 0.5s, and the recording time is about 5 hours (hours). The host computer can read the stored data through the RS232 interface. The host computer can visually Display the sailing track, the pitch angle of the sailboat, the pitch angle of the sailboat, and the left and right swing angle. Its system structure block diagram is shown in Figure 1.
2. Hardware design of sailing attitude instrument
The PIC16F877A microcontroller is used as the processor to detect the inclination angle of the sailboat by collecting the inclination sensor SCA60C, and then store the detected data in the AT45D081A-RI large-capacity Flash memory. Part of its hardware Circuit is shown in Figure 2.
The DS1302 clock chip records the data in the measurement and control system, and performs time calibration during recording. Its software and hardware are simple in design and accurate in time recording, which not only avoids the heavy workload of continuous recording, but also avoids the blindness of timed recording. The connection between DS1302 and CPU only needs 3 lines, namely SCLK, I/O, RST. The circuit principle that DS1302 connects with the one-chip computer is shown as in Fig. 2.
Adopt dual power supply mode, so that time information and data can still be saved without main power supply. DS1302 is powered by the larger of VCC1 or VCC2. When VCC2 is less than VCC1, VCC1 supplies power to DS1302.
AT45D081A-RI is a large-capacity Flash memory produced by Atmel, with a capacity of 4 Mb. It transmits data in serial mode and is powered by a single 5V power supply; it has the characteristics of low power consumption, small size, large capacity, fast transmission, compatibility with CMOS and TTL levels, and no data loss after power failure. Therefore, its hardware design and Software programming is easy.
The system communicates with the host computer through RS232C communication, and transmits the sailboat’s attitude in the sea to the host computer, which is finally managed and displayed by the host computer software.
3. Selection of inclination sensor
The system uses the SCA60C high-precision inclination sensor of Shanghai Langshang Technology and Trade Co., Ltd. to detect the inclination angle of the sailboat, and detects the pitch angle and the left and right roll angle of the sailboat through different installation methods. SCA60C is actually an accelerometer, which consists of a silicon micro-sensor and a signal processing chip; it is packaged in SMD form; by measuring the component of the earth’s gravity in the measurement direction, and then converting it into an inclination angle, its analog output characteristics are shown in Figure 3 shown. The arrow indicates the positive direction of acceleration. If the sailboat accelerates in the direction indicated by the arrow, or tilts in the direction shown in Figure 3, the output value will increase.
Among them, Offset is the voltage output of the sailboat at 0 g position (usually the output value is 2.5 V), and Sensitivity is the sensitivity of the device (usually the sensitivity is 2 V/g). For best accuracy, the actual output value should be used instead of the usual value.
4. PC software design
Using Delphi software to design the host computer of the sailing attitude instrument, read the data collected and stored by the sailing attitude instrument through the serial port, use the host computer software to manage the read data, and Display it visually in the form of a curve. You can learn the specific situation of the athlete’s training on the host computer. The software interface is shown in Figure 4.
The sailing attitude instrument is easy to install and debug, with advanced technology, rich functions and convenient maintenance, which can help sailors conduct scientific training and welcome the 2008 Beijing Olympic Games.