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 The Twinster was developed at GKN Driveline’s centre in Köping, Sweden

- wheel vectoring

GeneralMotors (GM) describe as yaw- damping – the systemloads different pre-sets according to the selection of the different drivingmodes – tour, normal and sport. Selecting thesemodes indicates the level of sensitivity to steering inputs required, with the highest level of yaw-damping in tour mode, acting to neutralise erratic inputs and corrections, above a specified tolerance for the drivingmode, into the most progressive and predictable cornering possible.

COMMERCIAL PROGRESS Choosing the Twinster systemfor the FocusRS highlights its performance enhancing technology, competing with otherAWD hot-hatch rivals where front- rear torque distribution is becoming the norm. The Vauxhall Insignia contract shows that the

technology also has an attraction in the executive segment:

according to JATO Dynamics,GM In addition to weight saving,

mechanical simplicity reduces the parts count compared to a conventional TV system, streamlining the tooling process. Continuing the pursuit of efficiencies, the systemdeclines the hitherto commonplace process of employing inside-wheel braking during cornering when over-speeding the outside rear, citing unnecessary wear on brake-pads. In its place is a process

Europe hopes theVauxhall Insignia Grand Sportwill lure buyers away from theVWPassat and Skoda Superb,which currently leadEuropean sales in the Insignia’s class.Here, stability, ride comfort, efficiency and safety standards are the chief concerns of buyer and manufacturer alike.GMEurope’s head of vehicle dynamics&AWDintegration for the Insignia,AndreasHoll, believes the handling package is a key selling point of the newmodel: “The car demonstrates perfectly balanced handling characteristics. It provides neutral steering behaviour up to a very high limit. In case of very aggressive

steering inputs theAWDtorque- vectoring functionwill be supported by theDWT-B(dynamicwheel torque – brake)module of theESCsystem.Both are tuned to react to the driver’s input commands in an unnoticeableway, and provide full directional stability and agility,” he says. “In the end, the car is able to provide

full traction capability aswell as safe and agile handling.Due to the lack of a conventional rear differential, the entire package is also lighter.All these attributeswill be appreciated by drivers all year round, and in all driving situations.” Holl describes the testing process for

theAWDpackage: “As usual,we start with component tests to achieve component-level specifications and durability.When this part is done, the first implementation in prototype cars takes place. The tuning of the various software parameters needs to take place in all possible areas aroundEurope. The dynamic vehicle testing took around 14 months.” Themain development areaswere:

proving grounds,Germany andSpain; winter tests,Sweden; handling,NürburgringNordschleife; gravel tests, southSweden; and Alp tests.

To complement the Twinster, the

redesigned Insignia has body changes to improve handling.Alower centre of gravity is achievedwith a sleeker, lower profile. Thewheelbase has been extended by 92mm, although the overall length of the car has only increased by 55mm; the reduced overhang also contributes to the car’s natural cornering capabilities. The AWDversionwill also bemated to a new eight-speed automatic transmission,with extended gear ratios. “The new transmission is aswell integrated in the drivermode control as theAWDsystem,” Holl explains. “The shift characteristics will be adapted to the pre-select driving mode or the calculated driver index to ensure perfectly balanced vehicle behaviour overall.” Replacing the first-generation Insignia

after a nine-year production run, the Grand Sportwill go on sale in theUKin the Spring. EE

February 2017 /// Environmental Engineering /// 43

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