DENSO Corporation has developed a new electronic control unit (ECU) for adaptive front lighting systems (AFS), which is approximately 70 percent smaller in volume compared to DENSO’s conventional ECU for the AFS. The new ECU is installed on the Toyota Estima launched this month in Japan.
The AFS redirects low-beam headlamps individually in a horizontal direction in accordance with steering angle and vehicle speed. As a result, this system can improve visibility during nighttime cornering, ensuring safer driving. In 2003, DENSO developed the world’s first AFS with Toyota Motor Corporation and Koito Manufacturing Co., Ltd.
“The number of ECUs in a vehicle is increasing due to the development of various information, safety and driving-support systems, and as a result, the demand for smaller ECUs is growing,” said Mitsuhiko Masegi, managing officer in charge of DENSO Corporation’s Driving Assist & Safety Product Division. “We developed the new ECU to meet this demand.”
DENSO reduced the size of the ECU by:
• Shifting the motor drive circuits, which control headlamp direction, to the motors;
• Adopting CAN (Controller Area Network) and LIN (Local Interconnect Network) communications for signal input and output, reducing the size of input and output connectors on the ECU; and
• Reducing the size of microcomputers and IC chips.
Adopting CAN and LIN communications also resulted in a smaller number of input and output wire harnesses, providing easy installation of the ECU.
In addition to its smaller size, the new ECU can provide more detailed light distribution control, depending on road conditions and vehicle speed, providing improved visibility. Specifically, at speeds of 30 kilometers per hour or more, the ECU can simultaneously redirect both the left and right headlamps. At speeds lower than 30 kilometers per hour, the swivel angle of the headlamp is controlled in accordance with the steering angle, regardless of the vehicle speed, thereby improving the visibility especially at intersections and sharp curves. Further, DENSO significantly reduced the cost for the new ECU through size reduction and standardization of circuits.
DENSO’s ECU for the AFS has an auto leveling function that controls the headlamps in a perpendicular direction. However, car manufacturers typically use an auto leveling ECU for models that do not have AFS, since the auto leveling ECU is less expensive than a conventional AFS ECU with the auto leveling function.
“Because we can provide the new AFS ECU at a lower cost, car manufacturers can use the ECU for both adaptive front lighting systems and auto leveling systems or only for the auto leveling system,” said Masegi. “They do not need to install different ECUs for the headlamp control functions.”
For more information, go to www.globaldenso.com.