What are ABC, ABD, ABS, ASR, BAS, DAC, DSC, EBA, EBD, EDS, ESP? Do you think they are just simple English letters? It’s not that simple in the automotive world. Today, we will give you a comprehensive interpretation.
ABC——Active Body Control System
The ABC system allows for quicker and more precise control of the car’s roll, pitch, yaw, bounce, and body height. With reduced body roll and minimal changes in wheel camber, tires can maintain better vertical contact with the ground, improving traction and maximizing the tire’s braking and driving capabilities. The introduction of ABC overcomes the conflict between suspension settings for comfort and handling, closely aligning with consumer expectations in both areas.
ABD——Automatic Braking Differential
This is a new product of the braking system, primarily designed to shorten braking distances, working in conjunction with ABS, EBD, etc. During emergency braking, the car tends to pitch forward, shifting weight to the front wheels and reducing the load on the rear wheels, potentially causing them to lose grip. In severe cases, this results in only the front wheels braking, leading to an extended braking distance. ABD effectively prevents this by monitoring the speed of all wheels, reducing the braking force on the rear wheels to maintain effective friction with the ground while maximizing braking force on the front wheels to shorten the braking distance. The difference between ABD and ABS is that while ABS prevents wheel lock-up during emergency braking for safe handling, it does not effectively shorten braking distances. ABD, on the other hand, allows maximum braking force while ensuring the vehicle does not skid, effectively shortening the braking distance.
ABS——Anti-lock Braking System
Without ABS, emergency braking typically causes the tires to lock up, resulting in longer braking distances due to sliding friction between the locked tires and the ground. If the front wheels lock, the vehicle loses lateral steering control and may veer off course; if the rear wheels lock, the vehicle may fishtail. This is particularly dangerous on snowy surfaces. ABS controls wheel lock-up by modulating brake fluid pressure, cycling through a process of locking and releasing the brakes, keeping the vehicle in a state of critical slip.
However, in some movie stunts, cars are often not equipped with ABS, allowing for slides and fishtails. Advanced racers who seek driving thrills also tend to avoid ABS. Ultimately, ABS is designed not for elite stunt drivers or professional racers but for the general public to ensure driving safety. In the 1990s, ABS was a highly sought-after feature in vehicles, and today, it is a standard feature in new cars.
ASR——Acceleration Slip Regulation System
As the name suggests, this system prevents drive wheel slip during acceleration, aiming to maintain vehicle stability, handling, and appropriate driving force, ensuring safety. The principle is straightforward: when the computer detects slip at a drive wheel, it reduces engine output and applies brakes to the slipping wheel until normal rotation resumes. Regardless of the luxury of the car, the contact area with the ground is only a few dozen square centimeters, i.e., the contact area of the four tires. If wheel slip is not controlled, the vehicle will lose control. It’s a misconception that only braking lock-up is dangerous; wheel slip during acceleration can also be problematic.
BAS——Brake Assist System
In emergencies, 90% of drivers lack decisiveness when braking. The Brake Assist System is designed to address this by detecting the speed at which the driver presses the brake pedal. If the driver quickly presses the brake pedal but applies insufficient force, the system assists and increases braking force to maximum within less than a second, shortening braking distances in emergencies.
DAC——Downhill Assist Control System
Similar to engine braking, to avoid overloading the braking system and to reduce driver burden, the downhill assist control operates when the transfer case is in the L position; at speeds between 5-25 km/h with the DAC switch activated, the system can automatically control speed without pressing the accelerator or brake pedal. The parking lights will automatically illuminate when the downhill assist control is engaged.
DSC——Dynamic Stability Control System
The DSC control system, developed by BMW, integrates the ASC automatic stability control system and traction control system, stabilizing the vehicle by selectively braking wheels that show tendencies to slip. On icy, sandy, or gravel surfaces, the driver can activate DTC mode with a button to enhance traction. The system’s intervention extends the limits slightly, increasing both traction and drive force, allowing for an extraordinary driving experience. Another function of the DSC is the CBC cornering brake control, which eliminates oversteering tendencies through asymmetric brake force control during slight braking in turns.
HAC——Hill Start Control System
The Hall effect speed sensor can sense both vehicle speed and rotor rotation direction with high sensitivity (detects at 0 km/h). When in gear and the wheels tend to roll back (insufficient drive force going uphill), the system automatically applies brakes to the wheels until they move forward again, enhancing safety during uphill driving.
HDC——Hill Descent Control System
This system actively senses hill gradient and road conditions, automatically controlling traction, braking force, and speed to maintain control and stability during ascent and descent, allowing drivers to focus on steering without worrying about acceleration or braking. The HDC system maintains optimal speed control on steep descents, simplifying and enhancing safety for novice drivers in off-road conditions.
EBA——Emergency Brake Assist
Under normal circumstances, most drivers apply minimal force when starting to brake, gradually increasing it based on the situation. If a sudden need arises for much greater braking force, or if the driver’s reaction is slow, this method can hinder timely application of maximum braking force.
Many drivers are also unprepared for the need to apply substantial braking force or react too late. EBA understands braking behavior based on the speed at which the driver presses the brake pedal. If it detects a panic increase in brake pedal pressure, EBA activates maximum braking force within milliseconds, much faster than the average driver’s foot movement. EBA significantly shortens emergency braking distances and helps prevent rear-end collisions in stop-and-go traffic.
Once it detects a rapid increase in brake pedal pressure and the driver continues to apply force, it releases stored 180 bar hydraulic pressure to apply maximum braking force. Once the driver releases the brake pedal, the EBA system enters standby mode. By applying maximum braking force earlier, the emergency brake assist significantly reduces braking distances.
EBD——Electronic Brakeforce Distribution
When braking, if the four tires have different traction conditions, such as the left tire on a slippery surface and the right tire on a dry surface, the frictional forces differ, leading to potential skidding, tilting, or rollover during braking (with equal braking force on all four tires). EBD functions by rapidly calculating the friction values caused by different traction at all four wheels during braking, then adjusting the braking system to match braking force with traction, ensuring smooth and safe vehicle operation.
In emergency braking situations where wheel lock occurs, EBD balances the effective ground traction of each wheel before ABS activates, preventing fishtailing and lateral movement and shortening braking distances. EBD is essentially an auxiliary function of ABS, enhancing its effectiveness. Thus, in terms of safety metrics, vehicles are often equipped with “ABS + EBD” features. Currently, domestic models such as the Honda Odyssey, Palio, and Siena indicate “ABS + EBD” during braking.
EDS——Electronic Differential Lock
This is an extension of ABS functionality, used to identify whether a wheel has lost traction, thereby controlling acceleration slip. Vehicles equipped with EDS can better utilize ground traction compared to standard vehicles, particularly on inclined surfaces where EDS is especially effective. However, it has a speed limit and only activates below 40 km/h to prevent slipping during starts and low-speed maneuvers.
ESP——Electronic Stability Program
This group of systems typically supports the functions of ABS and ASR (traction control system). It analyzes vehicle state information from various sensors and issues corrective commands to ABS and ASR to help maintain dynamic balance. ESP enables vehicles to maintain optimal stability under various conditions, particularly effective in situations of oversteering or understeering.
ESP generally requires installation of steering sensors, wheel sensors, side-slip sensors, and lateral acceleration sensors. It monitors the vehicle’s state and can automatically apply braking force to one or more wheels to keep the vehicle on its intended path, even executing braking actions up to 150 times per second in certain situations. Currently, there are three types of ESP: a four-channel system that can apply braking force independently to all four wheels; a two-channel system that can apply braking force independently to the front wheels; and a three-channel system that can apply braking force independently to the front wheels while simultaneously applying it to the rear wheels.
The most important feature of ESP is its proactive nature; while ABS reacts passively, ESP can prevent problems before they occur.
TCS——Traction Control System
This system detects the limits of tire ground contact and automatically reduces or cuts off power to a slipping wheel to maintain traction. During braking on slippery surfaces, wheels may slip, potentially causing loss of steering control. Similarly, during acceleration or rapid acceleration, drive wheels may slip, especially on icy surfaces, leading to dangerous situations. TCS is designed to address these issues. It uses electronic sensors to detect when the driven wheel’s speed is lower than that of the driven wheel (a characteristic of slipping) and signals to adjust ignition timing, reduce throttle, shift down, or apply brakes to stop the wheel from slipping. TCS enhances vehicle stability, acceleration, and climbing ability. Initially found only in luxury cars, TCS is now common in many standard vehicles. When used in conjunction with ABS, TCS further enhances vehicle safety. TCS and ABS can share wheel speed sensors on the axle and connect to the vehicle’s computer, continuously monitoring wheel speeds. When slipping is detected at low speeds, TCS immediately “alerts” ABS to act and reduce wheel slip. At high speeds, TCS signals the vehicle computer to reduce engine speed or shift down, preventing wheel slip and loss of control.
TCS is a sophisticated electronic device, but its nature is to constrain driving behavior and not to unleash the vehicle’s performance limits, making it less suitable for sports cars.
GPS——Global Positioning System
GPS is a radio navigation and positioning system based on 24 global positioning satellites, providing three-dimensional position and speed information worldwide around the clock. The positioning principle is that users receive signals from satellites to determine the distance, clock corrections, and atmospheric corrections, processing data to ascertain user location. Today, civilian GPS can achieve positioning accuracy within 10 meters. The unique features of GPS have attracted attention from the automotive industry, leading to investment in developing automotive navigation systems for positioning and directional display after the U.S. opened part of the GPS system post-Gulf War.
LDWS——Lane Departure Warning System
The LDWS alerts the driver through seat vibrations if the vehicle crosses lane markings without signaling. This device effectively prevents accidents due to driver distraction. LDWS comprises sensors on both sides of the front bumper and a vibrating device in the driver’s seat. The sensors emit infrared signals and analyze road conditions based on reflected signals, unaffected by weather or road conditions. When abnormal movements of the reflected infrared light are detected, the control unit activates the seat vibrators, prompting the driver to correct the vehicle’s path. The sensors are designed to recognize different colored road markings used in various countries, such as white, yellow, red, or blue, and can also identify traffic signs like directional arrows. To prevent excessive alerts at low speeds, this system activates only when the vehicle exceeds 80 km/h, and drivers can temporarily disable the warning function through the vehicle’s control panel.
FCWS——Forward Collision Warning System
The application of active safety devices like forward collision warning systems can significantly enhance driving safety, reduce traffic accidents, minimize economic losses, and promote family well-being and social harmony.
ACC——Adaptive Cruise Control
The Adaptive Cruise Control system is an intelligent automatic control system developed from existing cruise control technology. While driving, the distance sensors (radar) at the front of the vehicle continuously scan the road ahead, while wheel speed sensors collect speed signals. When the distance to the vehicle ahead is too close, the ACC control unit coordinates with the anti-lock braking system and engine control system to appropriately brake the wheels and reduce engine output to maintain a safe distance from the vehicle ahead. The ACC control unit typically limits braking deceleration to a comfortable level, and if greater deceleration is needed, it signals the driver to take action. When the distance to the vehicle ahead increases to a safe level, the ACC control unit resumes driving at the set speed.
Editor: @Cheng Qiongsen