Delta is a 'Driver in the Loop' simulator that can be used to validate safety vehicle systems and sign off vehicle settings. In motorsport, where the company has already supplied one F1 team, it defined aero, gearbox and suspension settings as well as predicting a lap time before the physical car was ever created.
By working in a consistent virtual world, engineers can cut months from a vehicle test programme with significant cost savings from being able to test roads and weather conditions from anywhere on the planet in a laboratory setting.
The Delta series simulator has a six degrees of freedom motion system, and is powered by 16 5GHz computers, with five projectors offering a frame rate that is five times faster than a cinema, projecting a 240 degree wrap around view on an 8m screen. The R&D Centre also features a full control room to monitor up to 300 channels of data, a separate viewing gallery and secure conference rooms.
"Simulators such as the Delta series in our new R&D Centre offer vehicle manufacturers a no-compromise method to reduce development costs and time," said Kia Cammaerts, founder of Ansible Motion. "Using our simulator has cut the validation time from 10 days to just three for an Electronic Stability Control programme for one particular car maker. Apply those kinds of savings in cost and time across the whole car and it explains why we are now getting more and more enquiries from global OEMs to see what our simulator can do."
Designing and building such a simulator has not been easy, but the first step was to define the operation of the machine and this was done by superimposing car racing data on simulator principles, which essentially involves fluid movements in the inner ear. Bob Stevens, chief designer at Ansible Motion, explained: "You cannot sense sustained G-Force because it is a fluid in a semi-circular canal [in the ear] and it just adopts the position, and so you have no sense of continued acceleration.What you have a sense of is change of acceleration, and so you don't need to carry on accelerating at 1-G so long as you have given the initial feeling that you have started to do that, and then you let the vehicle position itself back to a neutral point without the driver perceiving the reversal."
Cammaerts created algorithms based on these movements and married them up to real data from motor racing teams, so a certain manoeuvre produced a certain effect in the ear. Translating this into a machine involved the talents of Stevens, who commented: "So I was given forces or accelerations and a space envelope principally for all six degrees of freedom – longitude, lateral, vertical, pitch, roll and yaw [spin]. My brief was then to make the machine as small as possible, as light as possible and as cheap as possible."
The machine developed has X-travel, a wide travel table and a rotary table on top of which is a three degree of freedom machine to give pitch, roll and heave. "All we have is basic machine elements configured in a unique way," observed Stevens.
What it means is that, unlike other simulators, there is freedom of movement anywhere within the space envelope. The traditional simulator, typically the flight simulator hexapod, is a parallel machine and so all actuators have to work simultaneously potentially creating 'conflicts' at the extremes. "A hexapod can yaw when it is straight upright, but if it moves forwards it can't go sideway, so it can't yaw," explained Stevens. "So they buy a bigger machine and don't take the payload [the module the driver sits in] to its extremes – they end up with very large hexapods to do the same as our relatively small machine."
The initial design phase, having set the basic parameters, was simply trawling the catalogues for some of the key components, like the linear drives and actuators with the right stroke force and speed. But when Stevens started it was not simply a case of downloading some files into his 3D CAD design. "It was nearly all hand calculations," he said. "At the time it was all 2D CAD. I drew out all the links at all their angularities and worked out mechanical advantages and things at those positions and motor authority at those stroke and combinations of angles - it was all done the old fashioned way really.
"Since then we have got SolidWorks and it would have made it a lot easier in the early stages.It is greatly helping us now [building a second generation machine]; we are bolder with our decisions and things we make.Things we have made have always fitted together but in the early days we did have a few fingers crossed behind our backs, but now with SolidWorks we don't because we have seen it together as a virtual model."
To drive the basic machine there are six motors and on top of that in the payload there is one on the steering wheel, two on the seat belts and potentially three more motors for various things – different customers want different feedback from various loads. It is important that the motors themselves are not causing any feedback through the steering wheel.
"We have got somebody touching basically an electric motor only via a steering column and a hand wheel, it is very sensitive to buzz," said Stevens. "If the hand wheel buzzes, it's wrong, it has to feel like it is connected to wheels at the other end.As soon as you connect the electric motor for false feedback it hums and buzzes. We have done lots of work minimising that with screening and earthing and repositioning of drives as close to the motor as possible to reduce cable runs and changing connectors and various things to sort out those sorts of problems. We have been through so many different drives and motor configurations in the last five years - it is quite a can of worms."
The obvious mechanical engineering solution would be to put some damping to suppress unwanted feedback, but the whole purpose of the simulator is to maintain precision and response.
This philosophy extends throughout the whole system – it works better if there is no compliance or flex as this loses motor control. "We are actually a bit upset when people want to put in road car seats because it isolates the person and the person doesn't move where we are trying to move them.So, from an engineer's point of view, I would rather have them in a moulded-in race car seat because they move as one with the payload. The best way is to be as rigid as possible, and the best way to do that, as with most mechanical structures, is to make them small."
The result has been a simulator that has already attracted interest from the automotive engineers as it is the first to be designed especially to meet their needs.
