Crawl Control : Advics Regenerative Braking System AHB-Rx

Regenerative Hybrid Braking System

Toyota is a company that never stops evolving, a year passes and they are rolling out a new feature with such advancement and simplicity that it becomes a gold standard for the automotive industry. Toyota is pioneering in giving reliable Hybrid Synergy technology to all kinds of automobiles. Since we all know that improper maintenaince of the braking system in a hybrid vehicle adds to it being damaged and needs replacement quite often. Recently Toyota and Advics have come up with a better and more reliable braking system that has greatly improved the regenerative capacity of a hybrid car or truck. Toyota simply refers to it as Electronically controlled brake system (AHB-Rx)

Advics new technology has been adopted for the new Toyota Land Cruiser. The new technologies adopted this time are “next-generation off-road control (crawl control)” and “caliper-integrated electric parking brake for large vehicles,” which contribute to the Land Cruiser’s essential qualities of “reliability, durability, and off-road performance,” and play a part in making the car “easy to drive on any road in the world, and providing fatigue-free driving.”

Crawl control is a function that significantly reduces the burden on the driver when driving on extremely rough roads. It automatically controls engine output. The brake hydraulic pressure to avoid slippage and wheel lock and maintain an extremely low speed, freeing the driver from operating the accelerator and brakes. This improves steering concentration.

The Advics electronically controlled brake system (AHB-Rx) and high-performance ESC modulator (V3.5G), provides high responsiveness, smooth control. The operating time has been extended, significantly enhancing the vehicle’s existing strengths of off-road performance and peace of mind on rough, rocky roads and other serious off-road terrain. This has greatly improved the quality of the vehicle in practical use on snowy and dirt roads.

Cooperative Regenerative Braking

Cooperative regenerative braking intelligently distributes braking force between hydraulic brakes and regenerative braking based on the driver’s braking demand.

Conventional hydraulic braking systems consist of brake calipers, brake pads, and brake discs. When the driver presses the brake pedal, hydraulic pressure is generated, causing the calipers to press the pads against the discs. This process converts the vehicle’s kinetic energy into heat, which is released into the atmosphere to slow the vehicle.

In Hybrid Electric Vehicles (HEVs) and Battery Electric Vehicles (BEVs), regenerative braking recovers energy that would otherwise be wasted. By using the electric motor as a generator during deceleration, kinetic energy is converted into electrical energy and stored in the battery for later use.

This system significantly improves fuel efficiency in HEVs and increases energy efficiency in BEVs, helping to extend driving range. To maximize this benefit, it is desirable to rely as much as possible on regenerative braking during deceleration and reduce the load on the hydraulic braking system.

As shown in the diagram below, when the driver lifts their foot off the accelerator to slow down, mild regenerative braking—similar to traditional engine braking—is typically applied. Some vehicles default to coasting, which does not activate regeneration, while others allow the driver to adjust the level of deceleration using drive modes or steering-wheel paddles.

When the driver presses the brake pedal, the hybrid vehicle braking system calculates the required braking force based on the amount of pedal pressure applied. It then precisely controls the balance between hydraulic braking and regenerative braking to deliver smooth and consistent deceleration.

In the diagram above, regenerative braking is shown as a smooth, continuous line. In real-world operation, however, the regenerative braking force fluctuates slightly. Despite this, the total braking force—represented by the dashed line—remains stable and does not fluctuate.

This stability is achieved through accurate coordination between the hydraulic and regenerative braking systems. Without proper control, variations in braking force could occur, leading to an inconsistent braking feel and discomfort for the driver. The coordinated control ensures a natural, predictable braking response under all driving conditions.