Published on October 25th, 2012 | by Daniel Sherman Fernandez0
Ford Focus Engineers Create Class-Leading Driving Dynamics
The all-new Ford Focus went on a long road of meticulous engineering and extended testing before arriving at its much-vaunted driving dynamics that flatter the novice and reward the expert. From the very beginning, the vehicle dynamics team had a clear aim – build on the current model’s acclaimed agility and precision, maintain the high level of handling and performance and significantly enhance comfort. They defined the key strengths and examined exactly what each area meant and how it related to the respective components of the car.
One of the most important aspects at this stage is achieving harmony between the different attributes. “Precise steering, for example, is vital but it must not come at the expense of comfort or refinement, or customers would simply walk away from the car. To achieve very precise steering we ensure that the rubber bushes are stiff in all the relevant directions, for instance, but for a good level of comfort these same rubber bushes also have to be soft in the other directions.
Often the solution to finding that all-important harmony is found in making very small adjustments. “It still amazes me how much difference a small change to a single component makes – it’s a question of paying attention to the smallest details. We try to design every component for its exact purpose and then work out what we can do to make it even better.”
Winning “Dynamicist of the Year”
The team did such an outstanding job that one of the team members was named “Dynamicist of the Year” by Vehicle Dynamics International magazine. Jürgen Pützschler, C-car vehicle dynamics supervisor, was chosen from a three-person shortlist by the international panel of judges for his work on the driving dynamics of the new Ford Focus and C-MAX.
The panel took into account the reputation for driving excellence that both vehicles are earning around the world. “Ford’s family of C-platform vehicles are segment leaders for dynamics in every market they are sold. Jürgen and his team should be commended,” said panellist John Heider, vehicle dynamicist, Cayman Dynamics, USA. Pützschler said he considered the award an honour for Ford’s global team, which challenged itself to deliver top driving quality even as it improved the cars’ refinement. “Vehicle dynamics development is not about helping lunatic drivers to go even faster through corners, it’s about ensuring predictable, safe and confident driving – even for a novice – when performing extreme accident avoidance manoeuvres,” he explained.
Putting Focus’ dynamics to the test
The all-new Focus has clocked thousands of kilometres in Belgium, home of Ford’s high-tech Proving Ground in Lommel. This 796-acre site close to the Dutch border houses 80 kilometres of test track, replicating pretty much every type and condition of road possible. In use 24 hours a day, seven days a week, the Lommel Proving Ground was the perfect location to develop and fine-tune Focus’ class-leading driving dynamics.
The Proving Ground has a variety of durability, handling, NVH (noise, vibration and harshness) and performance areas. From gravel tracks, cobbles and giant kerbs to hill roads, mud baths and saltwater facilities, vehicles here are tested to the very limit, and beyond, of what they might be put through at the hands of a customer. There is even a train track for vehicles to drive over, though no train has ever run through the site.
Steering Rig Unique in Car Industry
The new Focus also features an electronic steering system, called EPAS (Electronic Power Assisted Steering). The team wanted to develop this system for the previous-generation Focus, but after 18 months of development work concluded that the technology wasn’t mature enough to provide the natural steering feel Ford customers had come to expect, and opted instead for a hydraulic system. In the meantime, the team continued working on EPAS and has now been able to develop it to a point where it offers a natural, intuitive feel, coupled with a number of important advantages.
When manoeuvring at low speeds, you value very low effort, and that can easily be achieved with EPAS. And then at higher speeds we can stiffen up the steering to give the driver really good road feedback. Another big advantage is the way the system can suppress steering disturbances, so you can be driving on a really rough road and feel almost no vibrations or any other disturbances. An additional feature that the team has been able to implement is Pull Drift Compensation. This helps the driver by counteracting constant steering torque, such as when driving on a cambered motorway. The system recognises this constant camber and applies some compensation torque so that the driver doesn’t have to counteract it. Much of the work on EPAS was done prior to the development of the car, on an industry-unique steering rig. Ford used the steering rig to understand and tune the electronic steering system. The steering system’s electronic controller contains 253 parameters, and it is impossible to understand and tune all these parameters while sitting in a car, so the rig really helped us speed up the development and the learning curve. Without this rig we never would have got such a deep understanding of the dynamic characteristics and the potential of the EPAS system, and we wouldn’t have been able to develop such a great steering feel.
The team also turns to technology when it needs to carry out reproducible testing. A Steering Robot can carry out exactly the same manoeuvre time after time, enabling them to understand the fine differences between settings.
Bringing it All Together
The result of the development team’s hard work is a car that is more agile and precise than the current Focus, while maintaining a high level of handling performance and significantly enhancing comfort. The details are remarkable – steering is seven percent more direct, the body is 16 percent stiffer, the track is wider, improving the balance between stability and ride comfort, the rear shock absorbers are larger, the front suspension camber stiffness is increased by 50 percent – but most important of all, these elements work together.
People will really enjoy driving the all-new Focus.