Feature: Automotive
Exploring haptic feedback A basic haptic feedback system typically comprises three parts: sensor(s), control system and actuator(s). Sensors detect the stimulus, such as a finger on the touchscreen. Tis input signal is digitised by an ADC and sent to a microcontroller. Te MCU determines the frequency and amplitude required to generate the desired vibration effect and uses this information to control the actuators, which generate vibrations. Tere are three actuator types to choose from. Eccentric rotating mass (ERM) types used to be the traditional motor of choice. Tey spin an unbalanced mass to create an uneven centripetal force, which results in forward and backward movement. Where cost is important and resolution not so, ERMs are still used in simple circuits. More common nowadays is the linear resonant actuator (LRA),
which uses electrical currents and magnetic fields to move a mass up and down along a single axis, generating vibration. Because these actuators don’t rely on inertia, LRAs have a much quicker response time than ERMs, making them ideal for automotive applications when reactions must be a lot faster. Applications that require a low profile or a more compact actuator
system might opt for piezoelectric-effect actuators. Tese operate at a wider range of frequencies and amplitudes compared to ERM and LRA actuators, generating more precise vibrations, which are ideal for touchscreens. Tey do consume more power than the other two types, but offer response times as short as 1ms, compared to 40ms for ERMs and 20ms for LRAs. When it comes to the control chip, the nature of these applications
means that haptic devices must have a tiny footprint. Touchscreens, for example, have a slim profile and are oſten tight on space, and the car rarely allows much room for additional electronics.
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. And lastly, noise is also an important consideration. Converting analogue information into digital signals is a noisy process.
Choosing an ASIC Tere are many off-the-shelf (OTS) ICs available for haptic systems today, but a tailored process through ASICs can offer the perfect solution. By removing unnecessary features residing on an OTS chip and investing in areas relevant to the application, ASICs can offer high performance at lower power consumption. An ASIC will also result in a lower manufacturing cost per board and smaller silicon area. With custom ASIC design companies can retain their IP. ASICs
are extremely difficult to reverse engineer or re-use in other designs, making them valuable in setting a product apart from the competition. Non-obsolescence is another advantage afforded by ASICs. Like
some other applications, automotive requires reliable chips to improve the driving experience but also safety. Design teams will integrate as much of the circuitry as possible into an ASIC and optimise it, reducing the overall component count and with it the potential points of failure. With an ASIC not only the overall size and power consumption are
reduced, but system reliability is greater. As our cars become increasingly connected, using latest
technologies such as haptic feedback implementation is only going to grow. As we seek to optimise every aspect of the driving experience, it’s only right to take that approach to component level if we want to build cars for the future.
18 October 2023
www.electronicsworld.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46
