Active safety is about helping prevent accidents. Systems that help maintain proper visibility and driving posture, antilock braking systems (ABS) and other technologies help achieve this objective.
In addition to developing and adopting ABS technologies, in many of its vehicles Mazda has supported braking through systems that combine Four-Wheel Antilock Braking (4W-ABS) with Electronic Brake force Distribution (EBD), which distributes and regulates braking force over the four wheels in response to driving conditions. We have also introduced other braking assistance features, adopted dynamic stability control (DSC) systems to limit side skids and advanced roll stability control (RSC) systems.
Moreover, for the new Japan version MPV and CX-7 released in 2006, we developed an optional radar cruise control system with an adaptive cruise control function that regulates the distance from the car ahead by means of a milliwave radar sensor. As experience is developed in the home market we will expand it to other markets.
The DSC system works to maintain vehicle direction and limits side skids by detecting a variety of data on vehicle status with an array of sensors and applying the brakes or decreasing engine torque automatically under computer control.
Within the capabilities of the tires, this system helps prevent oversteering and understeering - in which the vehicle does not turn in the direction the driver intends. Such phenomena occur when the driver turns the steering wheel sharply and the tires are unable to sufficiently grip the road surface due to rain, snow or other adverse conditions.
Sensors in the DSC System
The system includes wheel speed sensor/acceleration rate sensor/yaw rate (rate at which the vehicle is attempting to turn) sensor/throttle sensor/steering angle sensor/brake oil pressure sensor
- Understeering Control
During understeering, DSC reduces engine torque and applies the brakes to the inner wheels to limit front tire sideskid.
- Oversteering Control
During oversteering, sideskid of the back tires is reduced by applying the brakes to the outer wheels.
The CX-9 during a dynamic rollover test
Mazda launched the CX-9, an SUV for the North American market, at the beginning of 2007. The new CX-9 comes equipped with an RSC system, a cutting-edge safety feature.
The RSC system coordinates with the DSC system, which reduces side skids, and the traction control system (TCS), which prevents tire slip when the vehicle pulls away or accelerates. The RSC system intervenes when it detects roll direction and other aspects of vehicle movement and applies the brakes appropriately in response. The system adapts to various customer usage situations, such as driving with cargo loaded on the roof rack.
The new CX-9 equipped with this system has achieved a four-star rating - the highest of any SUV currently on the market - in the NHTSA's dynamic rollover test, which seeks to verify stability when the vehicle is subjected to roll forces.
The Mazda Pre-Crash Safety System introduced in Japan is an advanced active safety system implementing Advanced Safety Vehicle (ASV) radar technology.
A milliwave radar detector behind the bumper recognizes the vehicle ahead, oncoming vehicles and obstacles. When the system determines that a collision may occur, it first activates a buzzer and warning light. If the driver fails to press the brake pedal after the warning, light braking will be activated automatically to alert the driver. Finally, if the driver's evasive actions are delayed to the point where a collision becomes inevitable, the system engages the brakes automatically to reduce speed. The seatbelts simultaneously wind tighter in advance of the collision to increase the restraining force on the occupants and help lessen the injuries. This system has been adopted in the new Japanese MPV and CX-7 released in 2006.
- The System in operation
