Hybrid vehicle dynamics

Toyota engineers combined electronic control of the Estima minivan's braking and driving functions to create its new Vehicle Dynamics Management system, resulting in improved environmental and vehicle performance.

Toyota Motor Corp.'s new Estima hybrid minivan features a regenerative braking system to improve fuel consumption. The Electronically Controlled Brake (ECB) system was engineered, with assistance from Advics Co., Ltd., for high levels of environmental technology, safety, and driving enjoyment. Toyota engineers say a high level of dynamic performance was realized through the use of a new Vehicle Dynamics Management (VDM) system, which was developed to encompass control of both the braking and driving functions of the hybrid system. With the ECB, which is able to smoothly control the amount of hydraulic pressure applied to each wheel cylinder on an individual basis, functional enhancements can be added by modifying its software.

As shown in Figure 1, the vehicle responds to the driver's braking requirements by employing the maximum possible amount of regenerative braking force, with the friction brakes making up for the rest. To make this possible, the precise control of hydraulic force is extended down into the normal operating range of the braking system, without allowing the driver to feel the coordination functions of the regenerative and friction brakes.