People, automobiles and statistics

Tony Nixon: So it’s a damp wet morning here at the Land Rover Driving Experience at Gaydon. I’m looking at a Land Rover Discovery Four. We are gonna get this white vehicle that’s looking absolutely spotless pretty filthy I guess. The track’s some extreme slopes. I must admit the place looks quite intimidating. What I’m here really to find out about is the human element and exactly how these vehicles are designed to accommodate a wide range of heights and builds of different people. We know that the car can cope with this environment – but how do human beings cope inside the vehicle, and how is the vehicle engineered in order to enable people to cope?

We are going to meet Paul Herriotts, who deals with vehicle ergonomics and essentially makes sure the passengers are safe and comfortable in the vehicle whilst it is doing all sorts of ridiculous things.

So Paul, we’re interested in statistics and people and how one might apply statistics in the context of vehicle design or something like that or ergonomics where you’re struggling to try to ensure that you’re accommodating as many people as possible – ouch – we are certainly going down a hill!

Paul Herriotts: As we’re driving I’ll try and relay what we use our statistics for.

So – I’m in one of our Discovery cars and I just wanted to remind you a little bit about how we designed this car from the point of view of designing it from the inside out. We are very keen on user-centred design and designing around the human being and we really are trying to cater for that wide range of customers that we have. A very small Japanese or Chinese or an Asian lady may be only forty/forty-five kilos, perhaps approaching one metre fifty. And at the other end of the scale we may have for example in, um, the Netherlands we’ll have the tallest people. From a width perspective we’d be looking at some really heavy guys and we’re really trying to design the car around those people. And by laying out the vehicle interior around those drivers – excuse me while I’m braking – so we may have a vehicle like this with seven people in and I have to be aware that when we are off-roading we’re doing it now and you can hear me moving around. Our heads are moving around in the car and our bodies are swaying and I’m kind of cognisant of that movement that we have, and also of the anthropometry of the populations that we’ve talked about. So if I put those two together we should be able to design an upper canopy that has enough space so that no one hits their head when we are off-roading.

We’re a very data-driven specialism in ergonomics and we’re really looking for data from populations around the world about physical sizes. Now we’re not so interested only in stature. We really are thinking about people’s back length to stature or their leg length. We’re thinking about people’s proportions and we have significant data on that from people all around the world. And we can then begin to get a data set that really describes the population so we can start looking at a measure of central tendency. So then of course we talk about means or medians and we can also look at how the population is dispersed and there we might be looking at the standard deviation of the population. Sorry – need to concentrate on my driving for a moment!

Tony Nixon: We’re going down a steep slope here and we’re about to tip up on our sides so –

Paul Herriotts: We’re not about to tip up on our sides. We’re gonna take it steady.

Tony Nixon: This is getting quite hairy! So how do you want people to feel when they’re driving a course like this?

Paul Herriotts: Really the – the crux of designing vehicles like this is to let people feel in control and one of the things we’re trying to do is to really afford people with a great sense of all round vision. We talk about Land Rover Command driving position and what we’re talking about there is giving people an understanding of the size of the vehicle and the vehicle extremities so they have great confidence in the car but they also have great vision of the outside environment. So we’re driving now – I know exactly where my bonnet edges are. I can see the edges of the bonnet very well. I know where the edge of the car is. You can hear me tapping it here. But I’ve also got great forwards and side vision so I can see all these features that we’re driving through at the moment. And I know exactly where to place the car and exactly where to place the front wheels and that’s really because we try to design that in during the design process. So we’ve been able to put a range of people in the car so they have an understanding of where does the bonnet end. Actually we’re looking now at a metal bonnet but when that existed only as a clay in the design studio we could put small driver surrogates into the driving position and I could ask them as I’m looking across now ‘can you see the edges of the bonnet?’ And I would nip out and I’d put my little five pence piece on or a ten pence piece and I’d slide it along and I’d say ‘how much of the bonnet can you see?’ And – and that really has dictated the form of this car that we’re in. And so we have a very low, flat bonnet that’s very easy to read and we’ve got two great feature lines that run along it so that also gives you a great visual cue and so helps you understand where the front of the car is. And of course in normal driving it’s important to understand extremities of the car whether ones parking or manoeuvring. In off-roading it’s essential to have that understanding of where my car is and where the environment is around it so that I can drive in a safe manner. And the wonderful thing is we get towards the end of that design process and we start driving prototypes and then we have production cars, we really can see a tangible output for all that hard work. So all those years of discussion and poring over data and looking at statistics and at the end we have a physical vehicle, as we are driving now. And there’s a tremendous sense of pride that I can point at a car as it goes down the road and say ‘I did that bit and I did that bit.’ And it really is a satisfying thing to have done.

Tony Nixon: Paul, just tell us what we’re walking through here.

Paul Herriotts: We’re in our ergonomics lab and in this facility we helped develop our early cars and prototypes of cars or models of cars to ensure that they are optimised from an ergonomics perspective.

Tony Nixon: So before we get stuck into the detail what is ergonomics?

Paul Herriotts Ergonomics is a user centred discipline design products and workplaces to fit the needs and abilities of people. We can call it the science of designing for people. So we’re doing a lot of testing in here with a range of people of all sizes. We get them to come up to the car, to open the doors, to get in and out, to get a comfortable driving position, to get a view of the road.

And as you are aware we’re in an enclosed laboratory but up against the wall we’ve got our driving simulator and when people are sat in a car or a model of a car and they look forward in the windscreen and they do see something that feels very realistic and it really is to simulate what driving a car would be like in the real world.

So we’re looking fundamentally at a tarpaulin covering a big block so I can’t really tell you what’s exactly underneath there but you can see by the volumes that it’s a large Land Rover car that we’re working on. We take a model like that and just as we’re modelling the car we’re also going to model our customers. So we would bring in thirty, or forty or fifty people who are a representation in size of our customers from around the world. And we’re looking at ease of entry and exit. We’re looking at driving position. We’re looking at being able to see out of the vehicle. We’re looking at being able to have enough space and room and we take the feedback from those people in a very structured way. We look at what percentage of people of which size have said this and on the basis of that we make design recommendations and design changes.

The reason we’re doing this early on in the design process is it is at a stage when we can change the design. Things like what we call the belt line of the vehicles so where the windows start, crudely put, and the proportion of glass to metal. We can change things like door opening angles. We can make changes to apertures. We can look at form of the bonnet so I could try three or four different bonnets on there and we can tune the vehicle to be more ergonomically optimised. And as we’ve done that early on that can then feed into tomorrow’s cars.

How we get data from people is quite critical and one of the things we have in the lab is our measuring equipment. We’re interested in the discipline of anthropometry, the measurement of human beings. We can measure ourselves as adults. But we also have data on the small children to understand the space requirements and how we have to design our vehicles to accommodate this range of people.

Tony Nixon: Okay well let’s have a go at measuring my sitting height.

Paul Herriotts: Yeah you can Tony. If we can go over to our stadiometer and we also have our – our complex anthropometer for measuring such measurements as sitting heights. So if you want to take a seat we’ll take a measurement of you now.

Tony Nixon: Excellent.

So I’m with Louise Malcolm who is an ergonomist and she’s now going to measure my sitting height.

Louise Malcolm: What I’ll do is I’ll just get you to sit here on this platform with you facing this way. So if you keep your knees up there so we’ll try and get a ninety-degree angle between your upper and lower legs. What I’ve got here is a calibrated measurement that I can just bring down - are you sitting up nice and straight there because it makes a difference whether you’re slumped or upright - bring it down to the top of your head – hold it there and your sitting height is nine-seven-seven millimetres.

Paul Herriotts: Very nearly a metre!

Tony Nixon: Wow that’s me. One metre of …

Paul Herriotts: I can tell you what we can now do in our book of anthropometry is to look you up and see what percentile sitting height you are for a UK male population or within a UK male population.

Tony Nixon: It seems like people are getting bigger I mean if you look at sort of medieval doorways and things like that they appear to be very small, they’re either badly made or people are changing shape. I mean is there something in that?

Paul Herriotts: You’re right to identify that. Crudely speaking over time people are getting taller and this has some consequence for us in product design and in automotive design so we have some human modelling software which predicts the size of people in the future. And we can select populations from around the world. We can look at the sizes of those populations five, ten or fifteen years in the future. So let’s go and have a look at that now.

Louise Malcolm: So I’m sitting at a computer terminal here and what I’ve got up and running is our RAMSIS digital human modelling software. We’ve developed a JLR mannequin. It ranges from our shortest female up to our tallest male. And then in between in the image that we’ve got showing here, we’ve got some larger mannequins to represent people who are bigger in the population. And we’ve also got some Chinese mannequins because they’ve got different body proportions to our UK and US mannequins. So this next image that I’m showing is a picture of our Range Rover Evoke driving position.

So what I’ve done here is loaded in very basic CAD data so we’ve got a seat in there, the floor, the accelerator brake pedal and brake pedals and also the foot rest, a knee bolster so to look at knee clearance going forwards and then the steering wheel. And what this software does is it will position within the seat movement envelope a person of a particular stature and body dimensions into their appropriate driving position. When we’re looking at creating new mannequins we spoke earlier about having to project future sizes and so within a mannequin creation option we can choose what nation they come from. So for us China is a really important market so we might want to look at a Chinese female of medium height and then we can choose a reference here. So its SIT 2014 but we’ve got the option to project all the way up to 2030.

We aim to fit as many of our customers as possible so the seats are designed based on fitting a range of people and so by choosing the largest and the smallest we’re making sure that we include all of the extremes of the population. We generally design from a fifth percentile female to ninety-fifth percentile male.

Tony Nixon: So is there such a thing as an average person? You know when you’ve got all these different dimensions combined?

Louise Malcolm: There’s not really such thing as an average person and we would never design for an average person because you’re automatically excluding everyone who’s taller or smaller than that which is why we design for extremes. But if we were to take someone for example who was of fifty percentile stature it’s very, very unlikely that their sitting height, their leg length, their arm length would also fall in that fiftieth percentile range. So generally we’ve got different proportions.

Paul Herriotts: So Tony, when discussing percentiles as you heard Louise describing just now, if we talk about ninety percentile stature we always have that word associated with the percentile. So we’re looking at specific measurements and percentiles of those measurements. We don’t talk about ninety-fifth percentile men or fifth percentile females because that’s quite inexact and really doesn’t describe things in an appropriate way. So percentiles relate to specific measurements. So generally when we say ninety-fifth percentiles if that’s used in the motor industry people are referring to a ninety-fifth percentile stature.