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ELECTRICAL & ELECTRONIC COMPONENTS
Richard Mount, director of sales at ASIC design and supply company
Swindon Silicon Systems, explains the technology behind haptics, and how ASIC integration can take it one step further
stick vibrate when the plane was beginning or likely to stall, prompting pilots into action. Decades later, and gaming controllers began implementing haptic technology to add an extra layer of immersion to videogames. Now, with the automotive sector becoming
D
increasingly digitalised, it is next on the list to fully unlock the benefits of haptic technology. Haptics offer a new method of communication
between driver and vehicle. A car with haptic feedback technology might, for example, vibrate its steering wheel to warn you to brake if it thinks you’re getting too close to the vehicle in front; and a sensor that registers your vehicle drifting away from its lane can shake your seat. Haptic feedback also means that
communication becomes two-way. Early in-car infotainment systems often provided little to no feedback, but by offering some kind of tactile response, such as a vibration when you press a button, the driver knows that the vehicle has recognised their input and can keep their focus where it matters.
THE RIGHT ACTUATOR A basic haptic feedback system typically comprises a sensor, control system and actuator. Sensors detect the stimulus, such as a finger on a touchscreen. This input signal is digitised by an analogue-to-digital converter (ADC) and sent to a microcontroller. The microcontroller determines the frequency and amplitude required to generate the desired vibration effect and uses this information to control the actuators. The actuators themselves generate the
vibrations, with eccentric rotating mass or ERM actuators being the traditional motor of choice. These spin an unbalanced mass to create an uneven centripetal force, which results in forward and backward movement as well as vibrations. Where cost is the major factor and resolution is not of huge importance, ERMs are still used in simple circuits. More common nowadays is the linear resonant
actuator, or LRA. These actuators use electrical currents and magnetic fields to move a mass up and down along a single axis, generating a vibration. As they don’t rely on inertia, LRAs have a much quicker response time, making them ideal for automotive applications. Applications that require a low profile or a
AUTOMOTIVE
INDUSTRY TOUCHES ON THE BENEFITS OF HAPTIC TECHNOLOGY
more compact actuator system might opt for piezoelectric effect actuators. These can operate at a wider range of frequencies and amplitudes compared to ERM and LRA actuators, allowing for a more precise vibration, ideal for touchscreens. They tend to have a higher power consumption, but can offer response times as quick as 1ms, compared to 40ms for ERMs and 20ms for LRAs.
ASIC BENEFITS When it comes to the control chip, the nature of these applications means that haptic devices must retain a tiny footprint. And while low power consumption isn’t essential in mains powered systems, for anything battery-operated, the system must be optimised for the lowest power usage possible. Initial prototypes of haptic devices may be
achieved using a variety of off-the-shelf ICs, but for a complete solution, opting for a tailored design offers the best possible user experience. This can be achieved with an Application Specific Integrated Circuit, or ASIC. ASICs are designed exactly to fit a customer’s requirements. By removing unnecessary features and investing in areas relevant to the chip’s application, ASICs can offer a much
lower power consumption while maintaining high performance. This also results in a lower manufacturing cost per board. Custom ASIC design also means that
companies can retain their IP. ASICs are extremely difficult to reverse engineer or re-use in other designs, making them valuable in setting your product and company apart from the competition. Non-obsolescence is another advantage that comes with the use of ASICs over standard ICs. ASIC suppliers will have non- obsolescence plans ready to ensure a continuous supply of chips for the lifetime of the product. When it comes to automotive applications, the chip must be reliable if it is to improve the driving experience and safety. Design teams will integrate as much of the circuitry as possible into an ASIC, reducing the overall component count and therefore potential points of failure. So, as our cars become increasingly
connected, making more use of current and emerging technologies, the use of haptic feedback is only going to grow.
Swindon Silicon Systems T: 01793 649400
www.swindonsilicon.com
DECEMBER/JANUARY 2024 DESIGN SOLUTIONS 27
uring World War 2, haptic feedback systems were implemented into aeroplane controls, making the control
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