16 OPINION
Paul Beever, an automotive
engineer who spent 38 years at
Land Rover, recalls the ideas, trials
and dangers of creating the Hill
Descent Control system
Beever
›After graduating from the UK’s Loughborough
University, in 1985 I joined Land Rover’s chassis
department, where I did some analytical engineering
programming in the Specialist Design and Development
Services team, which then led to an opportunity to work on
traction control (before cars had such a thing) and then on
ABS, before joining the team delivering the fi rst full-time
4x4 ABS system, for the Range Rover (1990MY Project Quest).
I then led the team developing traction control for the
1992MY Range Rover, which was another world fi rst. These
were fast-developing new technologies and I was very happy
to work at the leading edge of engineering. Early on in
the development of the fi rst Freelander my manager (Keith
Parsons) and I were approached by the Freelander chassis
project manager, Mike Gallery, to help with a problem. The
Freelander couldn’t go down steep hills as well as other Land
Rovers. Without the low-range gearbox, the prototypes were
‘running away’ down hills due to the lack of engine braking so
we were asked if we could do something clever with the ABS
to sort it out. I thought we could do it, so I started by writing
out a specifi cation for what such a system – named Hill
Descent Control (HDC) – would do.
At the time the Land Rover technique for descending steep
slopes had four steps: select the correct gear to maintain
the correct speed for the descent; begin the descent; keep
your feet off the pedals during the descent to prevent sliding
downhill; and then complete the descent.
I added two steps: activating HDC via a switch after
selecting the gear, and switching it off following the descent.
I knew that many drivers wouldn’t follow these steps, so
HDC had to carry on working if the driver braked, ABS had to
work with HDC, if required, and we had to consider what would
happen if the driver used the accelerator pedal. Competitors
later introduced features that released the brakes if the driver
hit the accelerator pedal, but I had the concept of raising
the target speed with the accelerator pedal, which allowed a
normal (ish) reaction to that pedal, as had been the case with
low-range descents. We also knew that people would forget to
switch off HDC when they were not descending, so we worked
to prevent the brakes coming on if the vehicle was decelerating
at the same rate as was normally expected on level ground.
We also set a limit of 50km/h (31mph) for HDC braking and
reduced the control gains to reduce braking gradually as speed
increased, to remove that discontinuity.
The fi rst prototype was a Range Rover with the traction
control system hacked to make the brakes come on when it
moved. This enabled an extremely crude demonstration of the
HDC function on a slope in one of the car parks at Land Rover’s
Solihull site. After we had our ‘proof of concept’ we talked to
suppliers and I drew up fl ow charts to show how I thought the
software might work.
Paul Beever was a
technical specialist
within the driving
dynamics team at
Jaguar Land Rover
for 38 years. He was
responsible for creating
several innovations and
more than 22 patents,
including features
relating to off-road
and stability control
systems, the invention
of Hill Descent Control,
and the instigation of
All Terrain Progress
Control. A highly skilled
test driver, he learned
to drive (and ride
motorbikes) at school
when he was 13, and
started racing karts at
14. Now retired, he lives
in Bratislava, Slovakia.
VehicleDynamicsInternational.com • May/June 2020
There was an early test incident at the Eastnor off-road test
facility, still using a Range Rover as a fi rst prototype, when a
triple system failure resulted in a runaway down ‘Gearbox Hill’,
which was the steepest slope at the site. The driver could not
apply the brakes and the vehicle hit a newly built ramp at
the bottom of the slope, which was intended to stop vehicles;
instead the ‘ski jump’ profi le launched the car halfway up
a tree, where it seemed to hang in mid-air for a moment.
We then met up with Roger Crathorne, who ran the product
demonstration team, for an early trip up to Blair Athol in
Scotland, where we tried out early development software in a
real off-road environment using proper Freelander prototypes,
which had Maestro van bodies at the time. This test was more
successful and we got that warm feeling that we were on the
right track. Much of the rest of the development took place
at Eastnor and in the arctic winter testing area in northern
Sweden. We did a lot of safety analysis, as well as vehicle work
including FMEA and other reviews. Though this project was
well before ISO 26262 and functional safety, we covered that
side effectively by asking questions like ‘how could it possibly
go wrong?’ and making sure we were happy with the answer.
It’s over 20 years later now and my lucrative (for JLR)
patents have expired, but I am happy with the fact that HDC
is now an industry-wide feature and that we got the fi rst
versions pretty close to what is in production today across
the world’s automotive industry.
“The fi rst prototype was a Range Rover with the traction control
system hacked to make the brakes come on when it moved”
/VehicleDynamicsInternational.com