Vehicle stability system ABS development direction

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Vehicle stability system ABS development direction [Copy link]

The automobile anti-lock braking system (ABS) is an important way to improve and enhance the braking performance of automobiles
. It can give full play to the potential adhesion between tires and roads, and improve
the braking performance of automobiles to the maximum extent to meet the needs of driving safety. It has always been the goal pursued by people.
Although the theoretical basis of ABS has been established long ago, due to the limitations of related industries such as electronic technology,
reliability and price-benefit ratio have become two major obstacles in the development of ABS.
Since the 1980s, due to the development of electronic technology, the reliability of ABS has been improved. In addition,
the increase in automobile driving speed has caused wheel locking and sliding during braking to become one of the major hidden dangers of driving safety.
In order to improve braking performance and ensure driving safety, the use of ABS has been promoted.

　　In 2005, the domestic demand for ABS was 1.26 million sets.

　　All developed countries in the world have put forward mandatory requirements for automobile safety. In the 1990s
, developed countries such as Europe, the United States, and Japan formulated strict regulations to improve automobile safety.
Facts have proved that the development of ABS is closely related to national automobile safety regulations. In 1995,
the ABS installation rate of North American cars reached 70%, and the ABS installation rate of European cars was about 40%. At present, ABS
has become the standard equipment of cars produced in these countries.
　　In 1999, China formulated the national mandatory standard GB-12676 "Automobile Braking System
Structure, Performance and Test Methods" which has made the installation of ABS a mandatory regulation. By 2005,
the ABS installation rate of domestic vehicles will reach 50%. The installation rate of micro cars and buses is 20%,
which means that the demand for hydraulic brake ABS will reach 750,000-810,000 sets; while
the installation rate of medium and heavy trucks, large and medium buses is 100%; the demand for pneumatic brake ABS is 350,000-450,000 sets; thus
, the total domestic demand for ABS by 2005 will be 1.08 million-1.26 million sets. China's ABS products are in the initial stage, and the promotion threshold of pneumatic ABS is lower
　　than that of hydraulic ABS .
On the one hand, pneumatic ABS is mainly for heavy vehicles and buses. These types of vehicles are mainly
produced domestically, and the national mandatory regulations do not require these vehicles to be equipped with ABS
systems. China started research and development in this area early and has a good technical foundation. Hydraulic
ABS is mainly for cars, and most of the cars in China are joint ventures, and their technical
discourse is mainly controlled by foreign parties, so it is more difficult for domestic ABS systems to enter the car field.
　　At present, it is estimated that there are about 10-20 domestic ABS manufacturers, and they generally only do pneumatic
or hydraulic ABS. Few pneumatic and hydraulic ABS are developed at the same time. For pneumatic ABS,
foreign manufacturers are mainly German WABCO and KNORR, and their market share is estimated
to be about 80%. Although there are many manufacturers in China, there are no large-scale suppliers. Hydraulic ABS
is mainly German Continental, Bosch, TRW and Delphi. Domestic manufacturers are
weaker and basically have not formed large-scale production. However, in recent years, domestic companies have seen a good market
prospect and have invested funds to accelerate development and production.

　　The gradual upgrade of ABS system technology

　　involves the following technologies in the ABS system: First, sensors. Traditionally, ABS sensors
are mainly electromagnetic induction sensors. Currently, 90% of the domestic market is dominated by this type of sensor, and
almost 100% of pneumatic ABS uses this type of sensor. The advantages of this sensor are low cost and
strong resistance to harsh environments, but the disadvantages are that it requires a small working gap and often has no signal at low speeds
. In recent years, due to the development of semiconductor technology, Hall sensors have gradually
been used in hydraulic ABS systems. Its characteristics are small size, large working gap, signal amplitude is independent of speed, and
it can also test gap and direction, especially for products used in ABS upgrades. Therefore, Hall sensors
are gradually increasing.
　　The second is the ABS controller. At present, ABS controllers are mainly based on 16-bit single-chip microcomputers, generally using
dual CPUs, and some use single CPUs. The various hardware chips used, foreign major semiconductor
manufacturers have mature solutions, so the hardware implementation is relatively simple.
　　The ECU hardware is mainly developing in the direction of integration. Some companies use advanced
semiconductor technology to try to integrate power drive chips with CPUs, and various auxiliary functions
such as power supply and communication. In this way, the chip can be integrated into one or two devices,
greatly improving the reliability of the system. In terms of software, some people have tried to standardize ABS software.
Software development is moving towards graphics and automatic code generation, which will lead to higher
CPU computing speed and larger memory and program storage space.

　　ABS mainly uses CAN as the communication bus

　　. There are three levels of vehicle networks: A, B, and C. Level A is mainly based on its own electronics, and its
representative bus is LIN. Level C is mainly based on real-time control, and its representative bus is CAN.
ABS mainly uses CAN as the communication bus, pneumatic ABS mainly uses SAE J 1939 as the network protocol
, and hydraulic ABS is generally formulated by each manufacturer. Generally, the ABS communication rate is 500
baud . ABS is a safety system, so it generally sends information such as ABS status and wheel speed to
the bus. Systems with ASR also control the driving force through the bus.
　　With the development of electric brakes (Brake-by-wire), the bus speed and reliability are required to
be greatly improved. At present, there are buses with 1M baud to 10M baud, which
are: TTP/C, TTCAN, FlexRay, and each bus has its own characteristics
. Currently, no bus has entered the practical stage. The main issues are price and system fault tolerance
. In addition, the brake-by-wire system has not yet entered the stage of mass use
, so it will take time for this type of high-speed bus to appear.
　　Another part of the vehicle network is the diagnostic protocol. In the early days, ISO 9141 was generally used as
the hardware standard, and the application layer protocol was determined by the manufacturer. The current trend is to continue
the hardware interface of ISO 9141, and the application layer protocol is to use ISO KW2000.

　　Electronic braking will be the development direction

　　ABS technology was mature in the early 1990s. There has been no breakthrough in the past decade
, but the expansion of ABS technology has greatly improved the connotation of ABS.
The initial expansion of ABS was the anti-skid control system, which is divided into
two parts: brake anti-skid (EDS) and drive anti-skid (TCS), sometimes collectively referred to as ASR. On this basis, the rear axle braking force sensing control
, namely the EBD function, and the electronic power brake EBA were expanded. These expansions are still mainly based on ABS.
In the mid-1990s, ABS entered a new development. ABS was only a
subsystem of the new system, not a main system, but it still regarded ABS as an important component
.
　　Pneumatic ABS evolved into EBS, namely the electronic braking system, and on this basis developed into the stability
control system ESP. The stability control system mainly uses vehicle acceleration sensors and yaw
rate sensors to control the lateral stability of the vehicle, such as correcting oversteering and understeering
to prevent the vehicle from losing stability. There are also some systems that integrate rollover warnings into
such systems. The control of this system is mainly based on braking, so ABS is an important
component.
　　Hydraulic ABS has currently evolved into stability control, namely the ESP system. It controls
the lateral stability during the operation process. The general brake is used to adjust the lateral stability of the vehicle by adjusting the driving force.
At present, this system has been installed in batches, and domestic mid-to-high-end cars have begun to be installed.
The functions expanded on this basis include: combining the power steering system with ESP to better control the stability of the vehicle
. The next generation of products has been mass-produced, namely the electronic brake system, which changes the traditional
brake hydraulic transmission part to electric transmission, but the braking force is still generated by hydraulic pressure and master cylinder pump.
This can improve the response speed of the brake, reduce the braking distance, and realize
the function of Brake-by-wire. In the future, the hydraulic ABS system will transition to a full electronic system, but
reliability and cost are a very big obstacle. Full electronic braking requires the brake motor to have sufficient braking
force, but the current 12-volt power supply is difficult to meet the requirements. It can only become a reality after the implementation of the future 42-volt power supply system
.
　　In short, modern automobile braking control technology is developing in the direction of electronic braking control.
Due to its great superiority, all-electric braking control will replace the traditional hydraulic-based traditional braking
control system and occupy the dominant position in the next generation of braking control systems. At the same time, with
the development of other automotive electronic technologies, especially ultra-large-scale integrated circuits, the cost and size of electronic components are constantly
decreasing. The automotive electronic brake control system will be integrated with other automotive electronic systems such as automotive electronic
suspension systems, automotive active directional swing stability systems, electronic navigation systems, and unmanned driving
systems to form a comprehensive automotive electronic control system. In the future, there will be no
isolated brake control systems in the car. Various control units are concentrated in fewer ECUs and will gradually
replace conventional control systems to achieve intelligent vehicle control.

Wonderful viewpoint:

Domestic automobile safety should start with ABS

　　. The development of automotive brake control technology is constrained by the development of the entire automotive industry. With
the attraction of a huge automotive market, various advanced electronic technologies, biotechnology, information technology
, and various intelligent technologies will be applied to automotive brake control systems one after another.
　　There is still a big gap between China and foreign countries in this field. Foreign ABS technology has long been mature, and
currently it is mainly concentrated in the research of ESP and electronic brake fields. China is still mainly focused on ABS
research. Some universities have begun to intervene in the research of ESP and other fields, but they only focus on
theory and lack practical work. Another big difference between China and foreign countries in this regard is that foreign
research and development in the field of ABS is mainly carried out by enterprises, and the main papers published are also mainly from enterprises
, while universities only do some theoretical research work. In China, almost all research and development is done by colleges and universities,
and enterprises only start production after the products are mature. Enterprises lack their own development capabilities. Colleges and universities
are often able to carry out research and development well because they have better human resources and support from national policies,
but they lack the foundation and ability for industrialized production, which leads to slow technological progress.
　　Regarding automobile safety products, in addition to the well-known ABS airbags. In recent years,
the systems expanded on the basis of ABS include ESP stability system, EBS electronic braking system, ACC automatic cruise system
, anti-rollover system, automatic collision avoidance system, all of which are related to ABS. In addition, there are tire
pressure monitoring system TMPS and night vision system. Most of these systems have entered the commercialization and
mass production stage. However, ABS can be said to be the most basic system. If ABS cannot be
successfully developed, other more advanced systems cannot be entered or are imperfect. However, some systems
are less related to ABS, such as TMPS (automobile tire pressure alarm technology). Because it is relatively simple,
many domestic companies are currently developing and producing TMPS systems, which is not necessarily a very good
thing.
　　On the other hand, the number of domestic companies involved in ABS research and development and production has gradually increased, which has begun to cause
market confusion and has greatly affected the reputation of domestic ABS. Domestic companies should start with ABS to enter the safety field
, otherwise, it will be difficult to enter the market with higher-end products. Foreign manufacturers of ESP and other systems
all started with ABS products, and after more than ten years of hard work, they have achieved today's glory.
Although domestic companies are facing great market pressure, due to technological progress,
improved development capabilities, strong support from the government, and abundant human resources in China, I believe that China can
complete the development process of more than ten years abroad in a relatively short period of time, and enter
the research and development of ESP, EBS and other systems as soon as possible.