Programmed to fit

The Integrated Car Engineer checks whether a designer’s dream can become reality. David Fowler reports

Every product designer faces a constant battle to get the aesthetics of the product to fit its function. And nowhere is this more true than in the car industry.

But the stylist’s flowing lines on the drawing board may prove impossible to translate into reality when details like the driver’s sight lines or rear headroom have to be taken into account.

Now, a design tool developed by Lotus Engineering and software supplier Concentra promises to help car stylists get an instant idea of the practicality of their earliest concept sketches.

‘It’s a bit like a spell check,’ says Andy Hill, Lotus design manager.

‘You can’t always get a quick yes or no when you ask the engineering staff about an idea. So the designer takes a basic sketch and presses “engineering check”. It allows you to check feasibility at any stage of the project, especially at the early concept stage without involving the engineering department,’ he says.

The basis of the package is Concentra’s ICAD, a knowledge-based engineering system. Programming is done in the software’s IDL language, based on enginering terminology.

Concentra has just begun to market the package, called Integrated Car Engineer, which allows a stylist to check instantly if a sketch will create insuperable packaging problems in reality – and makes it easier to resolve conflicts when they do arise.

ICE began in 1995 as a two-dimensional package, when Lotus began to devise the Vehicle Layout System. It was to be a software version of a physical ‘layout table’ a full size representation of a vehicle chassis used to check whether mechanical components and human occupants would fit.

With the Vehicle Layout System, Lotus wanted something that gave an early indication of packaging or homologation conflicts.

‘You take a styling idea, and this package allows you to say for example whether a certain engine will fit, or whether you can fit two people in the back,’ says Rachael Evans, principal design engineer.

As enthusiasm grew for the system’s possibilities, it expanded from a 2D to a 3D system, and Lotus invited Concentra to market the package. Tata Technologies of India was brought in to assist Lotus in developing the new computer code.

Hill says ICE’s benefits come at an early stage of design. ‘That’s when you’re concerned about gettting the basic architecture right,’ he says.

‘In any design with many elements, if you optimise one element you may compromise many others,’ says Gary Brownhill, Concentra International automobile director. ‘We describe it as “the web of conflict”. It’s a universal problem across all walks of industry.’

The program, running on a Unix platform, starts off by offering the designer a number of templates or default body styles: hatchback, saloon, estate, sports two-seater or MPV. The outlines of the default design, which can be viewed in plan, from the front, back or sides, or as an isometric view, are manipulated on screen using the mouse pointer to match the designer’s sketches. A model can be built up from a plan view, some key measurements, a few critical lines and a few sections.

The designer can select options to look at in detail, such as powertrain, interior, lighting, exhaust, engine bay, wiper pattern and so on. Within each option a component or sub-assembly can be selected which the program adds to the drawing in a default position. This can then be altered to suit the designer’s preference using the mouse.

Taking the engine, for example, the system asks the designer to specify front, rear or mid-mounting, whether longitudinal or transverse, cubic capacity, number of cylinders and whether arranged in line or as a vee. Typical engine dimensions are contained in the software, with the option of putting in the measurements of an engine. Car makers adopting the software would input their own engines’ dimensions.

On suspension, the designer has a choice of MacPherson struts or wishbones at the front or rear, with the additional option of a torsion beam at the rear. Suspension travel, hard points and bush stiffness can be specified and output into an Adams dynamic analysis package. Based on the designer’s choice of gearbox, transmission and location, the system will automatically calculate driveshaft angles. The lighting module will display the legal range of positions for each lamp.

For the vehicle’s interior the designer specifies seat positions. From the position of the hip joint, using anthropomorphic data based on international standards the system will display the position of the occupants’ limbs and calculate how comfortable they will be. A 95th or 99th percentile human can be specified. The system shows ‘eye ellipses’ – the range of possible eye positions – and works out whether viewing angles through the windscreen meet legal requirements.

The dashboard and its components and any centre console can also be built up.

At any time, the system will display the rules and assumptions it is using and whether any have been contravened – the rear passengers’ legs hitting the back of the front seats, for example. ‘It allows you to get away with some clashes,’ says Evans. ‘There’s a fine line between giving enough freedom to be creative but with enough constraints to stop you doing something stupid.’

The system makes it easier for designers to experiment with repetitive jobs and variations on a theme.

‘Putting the information into the computer model can be tedious, but then the ability to manipulate or adapt it later is fantastic,’ says Hill.

One example is windscreen vision lines and wiper zones, a problem encountered in the development of the Lotus Elise, and which was solved by moving the driving position nearer to the centre of the car.

Lotus wants to develop links with other software suppliers and hopes to integrate the system with Silicon Graphics’ Alias design package. There are plans for links with Catia so that data can be transferred without having to translate it into an Iges file, as now. There may also be aerodynamics and emissions modules.

Concentra is marketing ICE to other car makers. Christopher Bangle, BMW design director, saw an ICE demonstration and described it as ‘the prototype for how all cars will be produced in the future’.

Concentra is waiting for a big manufacturer to commit itself to a deal. If that happens, Brownhill is confident ICE could become an industry standard.