Over the last few years, haptic technology has undergone significant advancements across a wide range of industries. Haptic devices are designed to create a sense of touch through vibration, force, or motion in environments where the opportunities for audio and visual feedback are limited. From consumer electronics to automotive interfaces, haptic feedback has become an integral feature that can enhance user experiences and create next-gen human-machine interfaces (HMI).
There has been a dynamic transition from conventional solutions to piezo-based haptic technologies, which provide speedy response times over high-frequency bandwidths in ultra-compact form factors. These devices have become essential in today’s automobiles, where limited space and power efficiencies dictate how haptic feedback can be employed on steering wheels, dashboards, and displays.
Figure 1. In today’s modern cars, haptic technologies play a key role on steering wheels, dashboards, and displays. Image from Adobe Stock (licensed)
The National Highway Traffic Safety Administration (NHTSA) reports that driver distraction in the US claimed the lives of 3,308 lives in 2022. Haptic feedback that mimics the tactile feel of buttons, keys, and sliders on touch displays can help ensure drivers remain focused on the road and free of distraction. But as vehicles become more advanced and equipped with the latest features, space becomes a valued commodity, and haptic feedback designs that might have been applicable several years ago are far from ideal today.
The State of Haptics
Conventional haptic solutions—those that took advantage of linear resonant actuators (LRAs) and solenoid solutions—were in widespread use in the automobile industry at a time when COVID-19 began interrupting supply chains. Manufacturing plant closures, transportation restrictions, and component shortages all had a negative impact on haptics, helping to drive the cost of components to an all-time high during that time. China, a leading manufacturer of those components, was facing import restrictions.
During all that, the automotive industry was prioritizing the development of haptic feedback systems to enhance safety, comfort, and convenience. Pandemic conditions ended up sparking innovation that increased the adoption of digital cockpits, infotainment systems feedback for touchscreens, and tactile buttons and controls. Post-pandemic saw the growth of driver-assistance technologies that leveraged feedback for intuitive interfaces. Haptics are continuing to play a pivotal role in enhancing the situational awareness of drivers and improving safety in autonomous vehicles.
Challenges in Haptic Feedback Design
As with any industry, there are challenges when it comes to haptic feedback designs for automobiles. Integration, for example, requires coordinating with others along the design chain, including manufacturers, suppliers, and technology providers.
Designing systems to enhance user experience while mitigating distractions is another challenge, especially when it comes to balancing feedback intensity and duration for alerts and notifications. Environmental factors also come into play, with design considerations needed for variations in temperature, vibration, noise, and lighting conditions.
Of course, cost and complexity play a pivotal challenge, as haptic feedback designs drive up manufacturing costs, potentially leaving customers to consider if those systems provide any value. Addressing those considerations when designing haptic systems requires collaboration and consideration to meet the needs of customers.
The new generation of haptic solutions had to move past LRAs and ERMs. These conventional solutions are limited in the type of feedback they can provide, whereas piezoelectric actuators make it possible for different high-resolution feedback types (vibration, pulses, clicks, etc.) while increasing the amount of mass that could be pushed (Figure 2).
Figure 2. Piezoelectric actuators go beyond LRAs and ERMs by enabling different high-resolution feedback types while also boosting the amount of mass that can be pushed.
Starter Kits Ease the Way
While new piezoelectric designs provide increased performance and enhancements, they are not a one-size-fits-all solution, and integration can be a challenge. To overcome those issues, companies have begun developing starter kits with a focus on space constraints and mechanical integration. These kits are designed to introduce mechanical designers and engineers to haptic feedback and show how mechanical integration works using a combination of physical and digital design products.
For example, TDK’s PowerHap Development Starter Kit provides an introduction to haptic feedback technology, complete with reference designs and a quick-start guide that engineers can use for fast prototyping. While the kit is ideal for automotive applications, it can also be employed to provide feedback for smartphones, appliances, ATMs, vending machines, gaming devices, industrial equipment, and medical devices.
This is in part due to the unique design of the PowerHap actuators, a design which makes them compact yet powerful. The basis of the PowerHap device is a piezo ceramic element to which stainless-steel bows (or cymbals) are attached to both the top and bottom sides (Figure 3).
Figure 3. The PowerHap actuator is a piezo ceramic element to which stainless-steel bows are attached. The bows act as mechanical amplifiers, similar to levers.
The bows act as mechanical amplifiers, similar to levers, increasing the displacement caused when the piezo element is excited with a driving voltage. The bows amplify the contraction caused by the piezo effect by a factor of up to 15, making it possible to move very heavy masses such as automotive displays. Figure 4 below shows the PowerHap designed into a display module.
Figure 4. Shown here is the PowerHap actuator designed into a display module.
Wider Range of Feedback
The piezo element allows PowerHap to produce a wider range of feedback over traditional solutions, such as eccentric rotary motors and linear resonant actuators. Unlike these entirely mechanical solutions, piezo actuators can operate across a wide range of frequencies, amplitude, and waveforms to produce multiple types and different degrees of tactile feedback.
PowerHap actuators allow engineers to tune the feedback and surface effects by adjusting their frequency, signal, and amplitude. What’s more, they can also function as sensors by applying pressure on the bows, which generates an electric charge.
The PowerHap Starter Kit comes packed with a seamless button assembly, a round button assembly, a driver board, additional PowerHap devices, a USB cable, and a quick-start user guide (Figure 5). There are additional add-ons to further enhance prototyping capabilities, including additional sensors for specific applications, such as automotive displays, buttons and modules, wearable technology, and even a stylus that mimics the sensation of writing on paper.
Figure 5. The PowerHap Starter Kit comes with a seamless button assembly, a round button assembly, a driver board, additional PowerHap devices, a USB cable, and a quick-start user guide.
Use Cases and Real-World Examples
Haptics are increasingly being integrated into AR/VR applications, where tactility and sensation can be critical elements in an immersive experience. Imagine training to use equipment in a hazardous environment without actually being there, or the ability to manipulate parts of an engine during its design phase to see how it functions before it’s ever built. Digital design company Weart developed its TouchDiver haptic glove to make it possible to do such things.
The company used PowerHap actuators to make its dream a reality, taking advantage of these devices’ compact design, ability to generate a significant amplitude, and wide bandwidth. The TouchDiver glove provides tactile feedback through pressure force, texture, and temperature sensations, allowing users to interact with virtual elements and environments. With the PowerHap actuators, the glove can render material roughness levels accurately.
All About the Driver Experience
Automotive has been the premier application for haptics over the last few years, and for good reasons. The shift toward connected vehicles has driven the need for haptic feedback in advanced infotainment systems and interactive interfaces, and manufacturers have prioritized feedback to enhance safety and usability for the next generation of vehicles.
Haptic feedback is also needed for autonomous vehicles where trust and safety are critical issues for drivers and passengers. Perhaps the number one reason haptic design is at the top of the development pole is that it drives innovation and creates new possibilities for immersive user experiences.
TDK’s PowerHap Development Starter Kit was engineered from the desire to make designing haptics easier, and they have achieved that goal and more. The automotive industry is capitalizing on the latest piezo-based actuators over conventional solutions, offering increased response times, varied tactile sensations, and compact form factors.
PowerHap actuators mitigate the challenges associated with conventional actuators, making it easier to develop prototypes without added costs and integration issues, driving innovation and immersive experiences.
Except where otherwise indicated, all images used courtesy of TDK Electronics
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