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冰..蓝扎古
(bluezaku)
= 新人指导员 =
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所 属：吉恩
等 级：上尉
帖 数：5644
ＥＸＰ：1549 |
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 发表时间：2006/2/17 1:17:00
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这个东西做了我1个半月时间，当时每天就睡3小时，早上上课，晚上打工，回来继续做-0-。
最后老师还算有良心，给了我一个A......
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简单说一下大致的原理- -
图1
我称这把尺叫数字游卡标尺。整把尺由单片机和一把安装有步进马达的普通游卡标尺组成。
另外尺上安装有一个电池包。
先说一下步进马达
图2
图2内有根轴的立方金属物体就是步进马达，此类马达和普通马达不同之处在于
1：该马达的轴可逐步旋转。
2：该马达轴所转动的角度，频率，方向都可由特殊芯片（MC3479见图3）进行控制。
图3
凭借以上特点，我们可以任意控制此马达的转速和方向。
回到尺上，该尺被设计为拥有两种功能：
1：手动模式
在此模式里，用户自行手动调节游卡标尺。
图4
图4内的电位器（黄色包裹物内）由一齿轮与尺连接，工作时从电池包（见图5内，尺的下部）内通以3V电压。
图5
当标尺滑动时，齿轮带动图4内的电位器改变电压，该电压被输入进单片机内，转换成数字形式，通过公式运算成长度。由此得出所量物体的长度。且被显示在LCD（图6）上。
如2V电压时，尺走了3英寸，那么我们即可将2V电压（需转换成数字形式）放入事先写好的公式内，转换成3英寸，显示在LCD上。
图6
2：自动模式
在该模式内，用户由键盘
图7
输入所需长度尺寸，按enter键输入。
图8
游卡标尺即可自行运走到所需尺寸之位置。
其原理即在于将输入之数字，转换成时间，根据马达轴自身的周长进行公式运算。
如1英寸马达走3秒，我们即可将输入的1。00换算成让马达正时针旋转3秒的公式内。
3秒后马达就能带动标尺，旋转到1英寸，我们所需的位置。
然后按键盘上任意键，马达逆时针旋转3秒。即游标卡尺回到初始位置
最终报告
CPJ655 Project Final Report
THE DIGITAL VERNIER
Pro. : Benjamin Shefler
Submitted by:
xxx,xxx xxx
ID: 048xxxx34
xx,xxx xxx
ID: 048xxxx30
Semester: Winter, 2005
E-mail:
xxxxx@learn.senecac.ca
xxxxx@learn.senecac.ca
SENECA COLLEGE OF APPLIED ARTS AND TECHNONOLGY – NEWNHAM CAMPUS
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Introduction
Our project is a digital vernier that is a precision instrument that can be used to measure internal and external distances extremely accurately.
Earlier versions of this type of measuring instrument had to be read by looking carefully at the imperial or metric scale and there was a need for very good eyesight in order to read the small sliding scale.
Digital Vernier can be easily used as the measurement can be displayed on the LCD display clearly. It is more convenient than measuring with early vernier.
And when using the early version of vernier caliper, it is also difficult to adjust it to get the specific length. Even if we look at it very carefully, sometimes we will still make some mistakes to get the value we want.
So a step-motor will be added to this vernier to move around and reach the value entered from the keypad in MIB board. So when we want a special length value, we do not need to pull or push the vernier carefully to get the right value. Entering the value that you want to get, the vernier will extend automatically. It is clear to see and more convenience than the old versions.
Manually operated vernier calipers can still be bought and remain popular because they are much cheaper than the digital version. Also, the digital version requires a small battery whereas the manual version does not need any power source.
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Operation Instruction
After connecting the power to the MIB, a welcome screen will display on the LCD play first. And then press the ENTER button, the program will process and menu screen displays on the LCD player. There are two options in menu screen:
1. Measure Mode and 2. Auto Mode.
Only one option can be chosen one time.
Option 1 will set the vernier to the determining mode. In this mode, we can pull or push the vernier to determine the distance that can be read as imperial and display the value on LCD play. With pressing the UP button on the keypad, we will return to the menu screen.
The option 2 will set the vernier to the auto mode. In this mode, you can press the value of distance you want by the keypad. And with the Enter button being pressed, the vernier will keep extending automatically until the length is same as the value that is entered before.
The unit for option is also imperial. When the digital vernier stop moving, the LCD player will display the menu screen again and wait for the new command.
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Theory of Operation
The theory of this digital vernier consists of two parts.
The first part is determining mode. The theory is as shows in figure-1. A gear is used to connect the resistor to the vernier caliper. Then when we pull or push the vernier, the resistor will also change the value by the rotating gear. With the change of the value of resistance, the voltage from the power supply will change too. Our program will convert the change of voltage units to the imperial and display it on the LCD play.
Figure 1: The structure of vernier
The second part of this project is connecting the step-motor to vernier caliper.
A step-motor circuit consists of step-motor, step-motor driver MC3479, capacitors and diodes. The schematic of step-motor circuit is mentioned in the appendix
Figure 2: The structure of vernier with step-motor
Our program first compare the value entered from keypad and then calculate how long should step-motor work to fix the value we want. Then step-motor will start work until the value is fixed.
The following formula is for calculating the time how the motor should work until arrive at the length we input.
Diameter of step-motor’s axis: 0.2inch
Perimeter of step-motor’s axis: 0.62inch
Because we use half step mode so each step is 0.9deg and we use 100HZ frequency make the motor work:
So 360deg/0.9degx0.01s=4s
We get that motor finishes one round needs 4s.
0. 62inch/1inch=4s/x
x=6.45s
So each round needs 6.45s and the factor is 645
The time T that motor should keep working equals to
T=645xnx0.01(n is the length we input)
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Future Developments
As mentioned in introduction, digital vernier caliper is much more expensive than the old version of vernier caliper. And it needs a power supply for it.
So in order to make the digital vernier more usually used than the old vernier, the cost should be reduced and the size of it should be smaller.
Because the equipment we have is not good enough to make a better precise.
The digital vernier ‘s precision can still be increased. Getting the closest value is the most important part of this vernier caliper.
And the digital vernier can be improved to use with computer. After the users determine the distance or image, the date will be transmitted to the computer. Then the picture can be seen on the screen of computer.
It avoids users to spending the extra time to draw the picture on the computer. This function will be helpful to some specific jobs like designing, cartography and etc.
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APPENDIX
PARTS LIST
Total: $320.00
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Hardware Schematics
step-motor.........................KP35M7
Connection of Stepping Motor
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Software Flowchart
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Troubleshooting
1. Why I can’t start the program when I push the reset button?
A: Please make sure any wires are not connecting the PE0.
2. Why I can’t make the vernier move when I using manual mode?
A: Please make sure that the switch of the Auto Mode is on the off side.
3. What can I do when the system shut down?
A: Please disconnect the red wire on PE0 and push reset button.
4. When I using the manual mode there is not any value displayed on the screen.
A: Please make sure that the switch of Manual mode is on the on side.
5. If you have done all of above and also can’t make the vernier work, please contact us.
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无视吧，今天我疯了- -|||
[被 = 冰蓝扎古 =(bluezaku) 于2006-2-17 1:26:43修改]
[被 = 冰蓝扎古 =(bluezaku) 于2006-2-17 1:57:51修改]
 
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冰蓝下的天空-0-
发表时间：2006/2/17 1:23:32
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