汽车倒泊防撞报警器的设计毕业设计论文.doc

毕业设计（论文）

题目： 汽车倒泊防撞报警器的设计

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毕业设计（论文）
开题报告

题目： 汽车倒泊防撞报警器的设计

系 专业
学 号： 　　　 　　　　
学生姓名：
指导教师： 　 （职称： ）
（职称： ）

xxxx年x月xx日
课题来源
由于随着科学技术和汽车工业的发展，许许多多的汽车安全装置也得到大力的发展。汽车上面安装防撞警报器能够极大的方便司机的驾驶，保障司机的安全，并且能在紧急情况下能自动刹车防止汽车之间的相撞。随着人们安全意识的提高，在汽车上安装防撞倒泊警报器将必不可少。
科学依据（包括课题的科学意义；国内外研究概况、水平和发展趋势；应用前景等）
在当今社会，知识的实用性越来越得到重视。如何从海量的知识群中找出有用的知识并付诸实践，这是很值得摸索的。
单片机的应用日益普及，汽车的数量急剧增加，保障汽车驾驶人员的安全也变得越来越重要了。目前在汽车警报器经过20多年的发展 ，已经历了从开始的由单片机的蜂鸣器到由频率控制声音的急促报警到进一步的可视的智能化防撞报警系统。
汽车防撞装置主要是通过车与障碍物之间的距离，车速信号的发射与接收由信号控制系统既是利用单片机来控制车速。并发出不同频率的报警信号。当车速与车距距离进入比较危险的状态时，单片机自动控制发出紧急制动信号刹车，以此来达到防撞的目的。
由上述可知，汽车与障碍物的距离只有在危险距离状态才有发生碰撞的可能，汽车防撞装置系统的设计任务主要是采集汽车与障碍物的距离和本车车速，并与当时车速下安全警报距离与危险距离之间进行比较，判断汽车与障碍物的距离是否安全。当达到的安全警报距离时能发出声音报警。
研究内容
在倒车时不断测量汽车尾部与其后面障碍物的距离，并实时显示其与障碍物之间的距离，在不同的距离范围内发出不同的报警信号，并且提高报警系统的稳定性，以提高汽车倒车时的安全性。本文设计了一种超声波汽车倒泊防撞报警器，本报警器具有以下功能：最大测距4.9m，最小测距0.1m，实时显示测得的距离；在不同的时间利用三个不同的超声波传感器进行测距，能够有效的提高报警的稳定性。在不同的危险距离范围内发出不同的频率报警信号，驾驶员还可以根据个人需要调整设置报警距离。利用555来控制蜂鸣器的发声频率，直接运用单片机的I/O口控制报警器的工作。能够大大降低软件的复杂程度。该报警器与其它报警器相比具有功能多、硬件电路简单、工作稳定可靠等优点。
拟采取的研究方法、技术路线、实验方案及可行性分析
研究方法：理论联系实际。

技术路线：理论联系实际。

实验方案：对比“基于AT89C51单片机的超声波防撞报警系统”跟“基于AT89C2051单片机的超声波防撞报警系统”，前者性价比更高，所以选择前者。

可行性分析：能够理论联系实际解决实际性的问题。此方案可行。
研究计划及预期成果
初步讨论基于AT89C51单片机来实现汽车倒泊防撞警报器的设计，分析了运用AT89C51和AT89C2051作为主控制器的两种方案。重点介绍了AT89C51来实现的方案。对控制器，超声波发射电路，超声波接收电路，高低频报警电路，LED显示电路等模块，以及运用单片机的I/O口如何具体的控制作了一定的说明。第四部分中，介绍系统的硬件框图、软件流程图、中断子程序流图等，给出了具体的软件实现的方案。利用51 系列单片机设计的测距仪便于操作、读数直观。测距仪工作稳定, 能满足一般近距离测距的要求, 且成本较低、有良好的性价比。
特色或创新之处
考虑非常周全，不但提供了相应的理论基础知识，一定的电子电路图，还为详细的设计过程截取图片
已具备的条件和尚需解决的问题
对于AT89C51单片机来实现汽车的倒泊防撞警报器尚取得了一定进展，但是还是有很多的不足之处：
（1）应该引入更加完善的显示系统，是司机能更加清楚的了解倒车时的情况。
（2）引入先进的语音模块，通过人性化的语音报警信号。
（3）在紧急情况，应该自动使汽车紧急刹车，防止汽车与障碍物之间相撞。
（4）应该对该警报器进行实际的测量，适当的进行调节，最大限度的减少误差。
　但是未来利用单片机来实现汽车的倒泊防撞警报器仍然有广阔的前景，随着单片机的功能日渐增强，能够使报警更加人性化
指导教师意见

指导教师签名：
年 月 日
教研室（学科组、研究所）意见

教研室主任签名：
年 月 日
系意见

主管领导签名：
年 月 日

外文原文

Microelectronic Engineering
South KoreabSchool of Information and Communication Engineering, College of Engineering, Inha University, Incheon 402-751, South Korea cDepartment of Electrical Engineering, College of Engineering, Choongang University,Seoul 156-756, South Korea.Available online 17 February 2006.
Abstract
We report on the fabrication of a polymer-based 2.5 Gbps × 4 channel optical interconnecting micro-module for optical printed circuit board (O-PCB) application. An optical waveguide array is used for optical transmission from vertical surface emitting laser (VCSEL) array to photodiode (PD) array and the built-in 45° waveguide mirrors are used for vertical coupling. The optical waveguide array and the 45° mirrors are fabricated by UV imprint process in one-step. We fabricate microlensed VCSELs by micro-inkjetting method, which reduced radiation angle of VCSEL from 18° to 15° for better light coupling. We use solder ball array and pin array for alignment between O-PCB and the electrical sub-boards with alignment mismatch below 10 μm in x, y and z axis. The fabricated optical interconnection module transmits data at the rate of 2.5 Gbps per channel.
Keywords: Optical interconnection; Photonic integrated circuit; Micro-fabrication; UV embossing
Article Outline
1. Introduction
2. Fabrication of waveguide array and 45° mirrors
3. Microlensed VCSEL
4. Passive alignment
5. Optical interconnect modules
6. Conclusion
Acknowledgements
References
1. Introduction
In the progresses of microprocessor and the input-output (IO) devices, the need for higher bandwidth is rapidly growing. High speed interconnects are demanding next generation IO interconnects of highly increased data capacity because today’s IO interconnects are suffering bottleneck in bandwidth at the IO interface. Many attempts to increase the IO interconnect bandwidth have emerged [1]. These attempts to extend electrical interconnect in more bandwidth manner are hard to solve fundamental problems facing the limitation of electrical properties over gigabits per channel data capacity.
Operation of electrical interconnect schemes in gigabit regime will meet bottlenecks related to the properties of electrical interconnects, including material properties, skew, jitter, EMI, and power consumption. To improve the performances of electrical interconnects, many efforts in signal processing techniques such as pre-emphasis, equalization, multilevel signaling, and coding, deterministic jitter are needed to keep the trace of the bandwidth progress [2], [3] and [4].
Optical interconnection has a potential as an alternative approach to solve these problems because optical interconnection has many advantages over electrical interconnection such as high frequency, high bandwidth, light, immunity to EMI, low skew, low jitter, no need of ground line, easy for impedance matching.
To realize an optical interconnection module for O-PCB application, various photonic devices like light sources, detector arrays, and waveguide arrays are needed. The waveguides are interconnected to light sources and photo-detectors in a multiple array. The 45° waveguide mirrors are used for interconnecting VCSEL array–waveguide array/waveguide array–PD array. Once the O-PCB is designed and fabricated it has to be put together with the existing electrical circuits such as driving circuits for micro-lasers and micro-detectors. Hence, we need micro-fabrication techniques for realizing optical interconnection module.
We carried out micro-fabrication for optical interconnection module, which include design and fabrication of waveguides, coupling schemes and passive alignment. For this, we focus on the following issues: One is the concurrent fabrication of a waveguide array and 45° mirrors in one-step in order to reduce the number of processing steps for low-cost production and another is a method to improve coupling efficiency between VCSEL array–waveguide array/waveguide array–PD array including the passive alignment method between the different parts of the optical interconnection module. This paper demonstrates a micro-fabrication of optical interconnection module to be used for the realization of optical printed circuit board (O-PCB) [7] and [8].
2. Fabrication of waveguide array and 45° mirrors
To use polymers as materials of the waveguide, embossing technique is used because of its relatively easy fabrication process. We fabricated polymer waveguides by UV embossing, which also involves fabrication of mold and replica. UV curable polymers are used as materials of waveguides and silicon mold is used to form waveguide patterns. For vertical coupling between VCSEL array and waveguide array and between the waveguide array and the PD array, we have to utilize mirror face at each end of the waveguide. To achieve this process, waveguide mold equipped with 45° faces at each end of the mold is needed to form the vertical coupling structure in a single fabrication step. We made a 12 channel silicon waveguides mold, which has 45° mirror face at the ends of each waveguide. The dimension of the waveguide is 50 μm width and 50 μm height and the waveguide layout pitch is 250 μm and the length is 7 cm. With this mold, we performed UV embossing to make embedded type waveguides.
To fabricate a 12 channel silicon waveguides mold, we etched silicon substrate with KOH-saturated isopropanol solutions in two steps: First is to make a vertical coupling path for the waveguides and the other is to make 45° slope for the fabrication of mirror faces. First, a metallic mask is patterned on the silicon substrate and the silicon is vertically etched with KOH to form a waveguide pattern. In the next step to form 45° slope, a thin film of SiO2 is grown on patterned waveguide. And photoresist is patterned at the end of the each waveguide structure and the ends of the waveguides are etched with KOH-saturated isopropanol solution to form 45° slope. After the SiO2 is stripped, the process of fabricating silicon mold equipped with 45° mirror is completed.
We fabricated 12 channel embedded waveguide array by UV embossing using the prefabricated silicon mold. Waveguide fabrication process is shown in Fig. 1. UV curable polymer, which is used as cladding layer with index as 1.45 at 850 nm wavelength, is dropped in the hollow cavity of a transparent substrate such as PDMS template. After silicon mold is pressed on template the UV light is irradiated. Silicon mold is detached and metallic film is coated on the 45° slope at the end of the waveguide to enhance coupling efficiency. And then the core polymer is dropped and a flat substrate is covered and pressed onto the core material which is also UV curable polymer with refractive index of 1.47 at 850 nm wavelength. The UV light is irradiated once again. After the upper and lower templates are detached, we can get a complete array of polymer waveguides with built-in 45° mirror face at each end of the waveguide.

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3. Microlensed VCSEL
One of the approaches to collimate the light from VCSEL arrays to the waveguide is the use of microlenses [9] and [10]. This method offers an increase in coupling efficiency and alignment tolerance. The volume of a polymer drop to fabricate these lenses is approximately a few tens of picoliters. We are able to control the size of the microlenses by controlling the amount of the polymer drops and by controlling the viscosity of the materials. UV curable polymer is used for inkjetting, of which the viscosity and the refractive index are 300 cps and 1.51 at 850 nm wavelength.
Shows one of the microlensed VCSEL array and microlensed VCSEL has a microlens formed by the inkjetting method on the aperture of VCSEL. Inkjetting of UV curable resin on the VCSEL, lens material is aligned automatically on the aperture of VCSEL. Shows a view of the system where the output power from the microlensed VCSEL arrays is measured for their divergence. The divergence angle of the laser light from the VCSEL is shown to become narrower by using microlenses by the collimating effect pf the light from VCSEL. Because of the microlens, the higher order modes from the VCSEL are suppressed by the cavity effect [10]. The emitted output from the VCSEL cavity is reflected back by microlens layer and is focused on the VCSEL cavity. During this process, the divergence angle of the VCSEL is reduced. In this case, the divergence angle of the VCSEL decreased from 18° to 15° after forming microlens. We conducted simulation study about the coupling efficiency between VCSEL and the waveguide by using the ray tracing method. As the divergence angle of the VCSEL was put into the calculation, the coupling efficiency of the VCSEL with microlens was found to be 0.44 dB is 0.96 dB which were better than that of VCSEL without microlens as −1.40 dB. Here dimension of waveguide is 50 μm width, 50 μm height and 7 cm length.
Refractive indices of the core and the cladding are 1.47 and 1.45, respectively, at 850 nm wavelength. The distance between the VCSEL and the waveguide is 100 μm.

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4. Passive alignment
Solder ball array and pin array are placed on the electrical sub-boards to bond the O-PCB and the electrical sub-boards with high precision. For precision alignment, solder ball array in diameter of 450 μm are used to thermally attach to the chip module. The solder ball array can be used for vertically alignment between the main O-PCB and the sub-boards within a mismatch below 10 μm. The size of the solder ball is 500 μm on average with standard error of ±5 μm.

Two types of pin arrays are used. One array with diameter of 1 mm is for alignment and the other with diameter of 200 μm is for electrical interconnection. The 1 mm pin array is used for lateral alignment between the main O-PCB and the sub-boards. Because of the impedance match, the pin array of the electrical interconnection is limited. Similar to solder ball array alignment tolerance of the pin array, about 10 μm, depends on variation of diameter of pin. The size of the pin is 1 mm on average with standard error of 10 μm.
We conducted simulation study about the coupling efficiency between the VCSEL-waveguide pair and the waveguide-PD pair by ray tracing. With the variation of misalignment of x, y, and z axis we calculated the coupling efficiencies. From the calculation we obtained the total coupling loss within 2.30 dB for the worst case of having position errors as large as 10 μm in the x–z axis and in the y axis, respectively. For example, when the position misalignment is 10 μm in the x–z axis and in the y axis, the coupling loss between VCSEL-waveguide is 1.59 dB and the coupling loss between VCSEL-waveguide is 0.71 dB. From the previous results, one can achieve the alignment between solder ball array and pin array can be achieved for alignment between main O-PCB and sub-boards with precision as about 10 μm in x–z axis and in y axis, respectively. Here the dimension of the waveguide is 50 μm width and 50 μm height. The refractive indice