Eric Grange, Industry Marketing Manager, Automotive, C&K
When we look at today’s automobiles, they’re beginning to look more like computers than vehicles. From a sea of headlines about autonomous, self-driving vehicles to the ‘smartphone-ization’ of the cockpit, it’s clear that the digitization of cars – particularly within the interior – is upon us and engineers must begin designing automotive components and switches to keep up with these advances in electronic technology.
In the past, automotive interior controls focused mostly on the basic functionality of the limited number of switches required on simple dashboards. As automobile design has evolved to prioritize more comfort and convenience features, more attention is now being given to the aesthetic characteristics and capabilities of the interior controls and switches that power them. Because of this, it’s critical that automotive engineers integrate these factors into the design process, just as performance and safety are.
Below are several considerations for engineers as they begin designing for the modern vehicle.
In the early days, when interior controls were primarily electromechanical, dashboards involved robust pushbutton switches with relatively long travel time – referring to the distance required to actuate the switch. However, as automotive interior subsystems have transitioned from electromechanical to electronic, it’s no surprise drivers now gravitate towards switches with less travel time. This is especially true for the mobile-first generation, who have grown up with hand-held electronics and are more familiar with short-travel switches. To cater to the more electronically-inclined driver, interface controls have had to evolve to smaller tactile switches with much shorter travel. Although this may seem like a small fix, many drivers consider old school, long-travel switches to convey lower quality.
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Figure 1. C&K tactile switch (expanded view)
Short-travel tactile switches usually include a metallic snap dome contact system, which provides the interface between the actuator and the switch housing. Although metallic domes typically have some advantages over their silicon counterparts, such as longer life cycle and a shorter travel, design engineers should keep in mind that the switch will often produce an audible sound when accessed. This can be a challenge when trying to create a pleasant, noise-free environment for the driver, and something that engineers should consider.
Gone are the days of numerous, independent knobs and keys to power every desired dashboard action. This is where touchscreens, or tactile screens, such as on a vehicle’s center console come into play. Many premium brands are taking the first step in integrating smartphone displays on the screen of the car. Still catering to the digital-first customer, a pleasant user interface (UI) is just as important to the car as details like the leather lining and stitching or dashboard design. By combining low-profile tactile switches within a wider actuating superstructure, designers can create a large clickable area that allows the driver to control multiple functions on a single surface, while minimizing power consumption and distractions behind the wheel.
Achieving a sleek design that integrates personal tech, smarter functions and meets safety requirements is no easy feat, so incorporating a flexible manufacturing process is one of the keys to success. This enables the manufacturer to adapt key components in the switch construction to achieve the consistency in performance sought by top automotive design engineers; for example, the aforementioned metallic snap dome that houses the tactile switch often causes unwanted sound. Through a flexible manufacturing process, the dome’s characteristics can be adapted to meet the vehicle’s requirements, including actuation force, travel distance, snap ratio, tolerance, acoustics, and other haptic factors.
Consolidating the design and manufacturing process enables the engineer to define the structure and material selection best suited for a given application, based on the specific needs of the specific automobile brand. Rather than using a pre-determined set of switch components, this customizable process allows for engineers to fine-tune the switches and components in the vehicle for optimal performance. For the automaker, this represents a significant advantage in manufacturing cost, time-to-market and risks.
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Figure 3. Different tactile switch structures generate varying levels of sound
One size doesn’t fit all so another key factor in facilitating the design process is the ability of the switch supplier to provide different product samples during the design phase. This can help weed out possible variations expected in volume production, given the accessibility of key elements. This provides the automotive engineer with a framework to accurately assess the performance and consistency of the switches under real-world conditions during the design phase, so there are no surprises when it hits the market – a win for everyone.
Last, but certainly not least, as automakers begin to make more technologically advanced and smarter vehicles, there are also safety considerations to be factored into the design process. Here’s where ISO 26262 comes in. This functional safety standard for electronic, electrical, and programmable electronic safety-related systems, focuses specifically on the needs of electronic systems in passenger cars (source: Programming Research). As the complexity of the electrical systems within a vehicle increase, so too does the risk of systematic failures. This standard, which specifies the safety requirements for different levels of functions, can provide guidance to engineers as they start designing, from driver assistance, propulsion and vehicle control to the hardware and software components that power the car, to ensure that they follow specific safety regulations. This has a significant impact on the specific electrical behavior requested of the components and switches in order to make the system more reliable and to enable failure self-detection.
As digitization and personal technology become conventional in vehicles, attention needs to be given to even the smallest characteristics of a car, factoring in feel, sound, comfort and convenience. Fortunately, automotive engineers are beginning to take a more holistic approach to design by implementing more of these factors into the layout of controls and switches, for better feeling, functioning and looking cars.