New Toyota Models Protect Passengers and the EnvironmentPosted on May 25th, 2005
By Nina Russin
Toyota is making hybrid technology and active safety key elements of its future product strategy. A hybrid version of the Highlander sport-utility vehicle goes on sale in June, and a hybrid Camry sedan is in the works.
New accident avoidance technology, including stability control, pre-collision, kinetic dynamic suspension, and adaptive cruise control, will help car owners reduce the risk of collision and injury.
The hybrid and safety technology work in tandem. Engineers use common microprocessors and electronic actuators to replace traditional mechanical systems. The electronic systems can react faster to driving conditions, improving vehicle performance. They also have fewer moving parts which can reduce maintenance costs in the long run.
Camry Hyrbid production begins in 2006
The Camry sedan is the fourth model to join Toyota’s hybrid family, which includes the Prius, Lexus RX 400h, and the Highlander hybrid. The new Camry, which goes into production at the end of 2006, will be the first Toyota hybrid built in North America. Toyota’s Georgetown, Kentucky plant, which currently produces the gas-powered Camry, Avalon and Solara, will produce about 48,000 hybrid Camry models annually.
Toyota has yet to release details on the new Camry sedan, but it’s a safe guess that the new Camry will utilize the same hybrid synergy drive that debuted in the Prius. This full-hybrid system allows the vehicle to operate in pure gas or electric mode, as well as a combination of both.
By operating the car with electric power only when energy needs are low (such as idling in traffic), the system significantly increases fuel economy.
A hybrid version of the Lexus GS also debuts for the 2007 model year. The new luxury sedan will go on sale some time next spring.
New active safety system helps drivers avoid accidents
While passive safety systems such as airbags and seat belts reduce passenger injury during a collision, active safety features, including antilock brakes and traction control, help drivers avoid accidents altogether. Since the advent of on-board computers, manufacturers have been able to introduce a host of active safety systems that would not have been feasible a few decades back. Recently Toyota brought a group of journalists out to its Arizona proving grounds to showcase the latest and greatest of what it has to offer.
Better off-road performance and handling
A “kinetic” dynamic suspension system, available on the Lexus GX 470, enhances on- and off-road handling, by varying the amount of torsional stiffness in the front and rear stabilizer bars. When the driver is traveling at high speeds on paved roads, the stabilizer bars have maximum stiffness, to keep the vehicle flat during cornering. However, if the driver goes off-road, the bars disengage. This allows the wheels to articulate according to need. The result is better traction on uneven trails, and a more comfortable ride.
Hill ascent and descent assist systems prevent the wheels from slipping on step grades. Both systems, which debuted on the current 4Runenr, are also standard on the Lexus GX 470. Descent control assist is also optional on the Tacoma 4 x 4 pickup.
Wheel speed sensors detect wheel slippage at each corner of the vehicle, and send that information to an on-board computer. The computer uses the brakes to restore traction. As a result the driver can stop on a steep incline without sliding sideways or backwards. Accelerating from a stop is no different than it would be on a flat surface.
The hill descent assist utilizes the brakes to maintain a speed of two-to-four miles-per-hour on steep hills. The driver maintains directional control better than if he was to apply the brakes manually.
High-tech steering systems share hybrid components
A new stability system called “vehicle dynamics integrated management” brings together a variety of active safety features in a manner that is imperceptible to the driver. The system integrates antilock braking, stability control, traction control and brake assist, to prevent the driver from losing control of the vehicle. Sensors that detect steering angle, yaw, deceleration, wheel speed and braking feed information to an on-board computer.
The computer can vary braking at each of the wheels or reduce engine power to prevent the wheels from either slipping or locking up. This is especially useful when the driver is making an emergency evasive maneuver, or when traveling on wet or icy roads.
The systems can also compensate for situations in which traction varies between the four wheels. A good example is when a driver hits an ice patch on one side of the car. The computer limits wheel spin on the side with poor traction, so the vehicle moves forward in a straight line.
An electronic steering assist function substitutes the electric motor used on the hybrid car steering systems for a hydraulic pump. Steering effort is lightest at low speeds, such as maneuvering in and out of parking spaces. At high speeds, there is more steering effort, to make the car more stable.
The new system can make subtle changes in the steering angle ratio, to compensate for side winds. It also compensates for the slight lag in steering response that occurs in all cars. As a result, the driver is able to make faster lane changes, or move around an obstacle more quickly.
The VDIM system is available on the Toyota Highlander Hybrid and Lexus RX 400h sport-utility vehicles, as well as the Lexus GS 430 sedan.
Adaptive cruise control takes the stress out of urban commuting
An adaptive cruise control system available on some Sienna minivan models, the Avalon Limited sedan, Lexus 430 sedan and Lexus RX 330 sport-utility vehicle, compensates for changing traffic speeds. The system uses a laser sensor behind the grille to monitor the vehicle ahead.
The driver determines the following distance using a function on the cruise control stalk. The following distance can vary from about 100 feet to 245 feet. The driver also chooses the highest speed at which the vehicle will travel, similar to conventional cruise control.
When the car is traveling in traffic, the system will maintain the preset following distance by varying engine acceleration and braking. The cruise control will only function at speeds over 25 miles-per-hour. It cannot make the car come to a complete stop. When it senses that the car ahead is stopping, it slows the car down and sets off an audible alarm, alerting the driver to apply the brakes manually.
Pre-collision system reduces damage and risk of injury
A pre-collision system, introduced on the Lexus GS 300 sedan, helps to reduce collision damage and injury when an accident is unavoidable. The function uses the same radar sensor as the dynamic cruise control to detect obstacles in front of the car. If the vehicle computer determines that an accident is unavoidable, it will automatically increase tension on the front-row seatbelts to protect the driver and passenger. As soon as the driver touches the brake, a brake assist function applies maximum braking force. This activates the antilock braking sooner, and reduces the stopping distance.
Making cars safer by reducing human error
According to Toyota’s internal research, 70 percent of fatal car accidents are caused by driver errors. While the technology behind these safety systems is complex, using them is simple. They operate automatically, often before the driver becomes aware of a dangerous situation. In other words, they make us better drivers without us even knowing it.
Virtual models help engineers study the effects of injuries
We are all familiar with the crash test dummies that car engineers use to determine how various types of impacts affect human bones. They also allow the engineers to measure chest compression, so that airbags and seatbelts can do an adequate job of protection.
But the dummies can’t help engineers gauge the effects of collisions on a person’s internal organs and muscles. Recently, Toyota introduced a new virtual modeling system that helps to fill that gap. Toyota engineers worked with Wayne State University, Virginia Tech and Virginia University to compile the data for the new system.
The modeling system, called THUMS (Toyota Human Model for Safety), has taken over a decade to develop. The THUMS family includes a typical adult male, female, a six-year-old child, and two pedestrians. Engineers use the virtual system first, before belting the traditional crash test dummies into the front seat.
“The dummies are just a measuring machine,” said Seigo Kuzumaki, vehicle safety engineer for Toyota. The THUMS family brings the human element into collision testing so that new cars can protect us better, inside and out.
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