Introduction
With over 1.4 billion cars worldwide, it is easy to assume that the only product of the automotive industry is the family car. However, the market for industrial, commercial, and agricultural vehicles is not only growing, but it is also embracing the latest technology.
Even as these vehicles are becoming increasingly sophisticated, a significant number will need to operate away from smooth pavements and city blocks. Designing the latest high-performance off-road vehicles is presenting new challenges for the automotive industry.
The Automotive Environment
Whether this new technology is deployed on the smart farm or at the largest mining facilities, the key concern for off-road vehicles will be the environment. While the automotive environment may not be the most extreme to be experienced by man-made machinery, these operations take place in demanding conditions, and equipment must be able to resist all conditions. A wide range of temperatures, moisture, and prolonged exposure to sunlight means that off-road equipment must be designed with care.
To protect sensitive electronics, enclosures must provide a tight seal against the ingress of water ranging from rain showers to full immersion in puddles for days on end. However, a component that is fitted to the outside of the enclosure, such as a connector, must provide the same level of protection as the enclosure itself. This means that the designer must be fully aware of the application and how it will be used in the field.
The use of IP ratings makes this easier to understand. IP ratings use a 2-digit code to signify the level of protection against the elements. Devices that work in sheltered locations might need a rating of IP65. This describes resistance to light spray and rain showers. However, equipment that will be immersed in water for long periods would need a rating of IP68.
Other equipment will need to resist dynamic pressure. This is often created by pressurised water jets used for cleaning agricultural machinery or in mining systems. The rating required for these conditions would be IP69K, where the K denotes the exposure to dynamic pressure. By understanding these ratings, the engineer can be fully aware of the performance of all the components selected for their design.
Extremes of temperature will also influence the protection of the equipment. Devices designed to be installed outside may be exposed to the cold of mid-winter in the Canadian north or the temperatures of equatorial Africa. This variation in temperature means that designers must choose materials with care to ensure that they continue to perform at each extreme.
This is made more complicated as some polymers become unstable under prolonged exposure to the ultraviolet (UV) component of natural daylight. Mechanical reliability will also be an important consideration. Vehicles contain many moving parts, and these must be capable of resisting the shock and vibration caused by uneven surfaces, especially in off-road environments.
The conditions in which the vehicle operates therefore has a major impact on its reliability. However, customers demand a level of performance that is unheard of in other industries. In the aerospace world, the reliability of aircraft is sometimes measured by the number of hours of maintenance required for each hour of flying time. Despite this, every pilot will still perform visual checks before every flight, even when the aircraft has been maintained correctly.
This does not happen in the automotive world. Vehicles are often only serviced after pre-determined intervals and, despite the advice contained within the user manual, very few drivers perform any kind of check. Instead, they simply jump in and expect their car to start on the first attempt. This combination of extreme environment with the expectation of flawless reliability is the key challenge of off-road vehicle design.
