The role of haptics in automotive electronics

Sponsored by TDK

There is little doubt that the automobile has changed society over the past century. Cars have increased personal mobility, changed the way purchased goods are transported and revolutionized mass manufacturing. For many, driving an automobile is a rite of passage. To them, the feel of a car on the open road is an experience like none other.  

Like a well-fitted glove, the controls within a car should feel intuitive and responsive. Feedback from these controls should incorporate touch, sight and sound to stimulate the senses and add to the driving experience. Haptics can significantly add to this experience and much more.  

Haptics Defined

Haptics refers to the use of technology to stimulate the senses of touch and motion – in other words, use of the technology simulates the ways things feel, react, move or change when force is applied. Haptic feedback is created by electronically moving a mass – either electromagnetically or through a piezoelectric effect. 

In the case of electromagnetic movement, devices can either shift a mass in a linear direction (referred to as linear resonant actuator or LRA), or spin an unbalanced mass to create motion (called eccentric rotating mass or ERM). On the other hand, a piezo haptic actuator sends an electrical signal across material to distort it and create movement. The force generated is caused by the physical displacement of the material. 

Piezo haptic actuators can create complex waveforms to simulate a variety of motions and effects by independently controlling both the frequency of vibration and amount of displacement. This is not possible with LRA or ERM devices. In addition, piezo actuators offer a faster response time, consume less power and come in smaller sizes than other devices. 

Automotive Haptics

When properly employed, haptic feedback ensures a positive user experience while minimizing user error and adding emphasis of action taken. Haptic actuators are typically used to either simulate the feel of an electromechanical switch or to augment the artificially produced feedback and interaction with an electronic interface. This feedback is crucial to the control, safety and comfort of the driving experience. 

For example, when a mechanical button is pushed to turn-on the radio or a volume knob is turned, the user immediately feels resistance and knows the device has completed the intended action. One trend is to replace mechanical buttons with electric buttons or small displays. Haptic actuators are needed to give the tactile feedback that a button was pushed, or a knob turned. In this case, the haptic device responds to pressure in a way that provides immediate feedback that satisfies the senses of the user. 

Haptic technology in pedals, seatbelts, steering wheel and seats can provide the driver feedback for a myriad of actions, and are incorporated into lane-assist, safe-distance warnings and other features. 

Design engineers are increasingly implementing haptic feedback into the various control panels of the vehicle. Doing so reduces the need for vehicle operators to look away form the road and increases the overall safety of the driving experience. 

In addition to enhancing safety features, haptic technology allows for increased personalization of the driving experience. Haptic feedback can be defined, modified and controlled by software. As a result, it offers designers potentially endless configurations and a flexible, customized experience. 

Designing Haptics

Numerous studies show that consumers prefer haptic feedback on surface and display technologies. Virtual or “soft” buttons and sliders on a screen almost feel like physical devices to the human touch, even though they are not. This allows for new innovations and adaptive user interfaces with haptic technology.  

To illustrate this, design engineers may use software to change the context or function of soft buttons in a vehicle by providing tactile feedback to let the driver know that an exterior mirror has reached the maximum limit of movement or that a window is fully closed. 

In implementing haptics, design engineers should be careful not to complicate a task or confuse the user by providing too much haptic feedback, especially when it is not expected. They should use haptic technology to simplify the user experience, minimize distractions and communicate important concepts. 

Some vehicle manufacturers have already begun replacing the center console with a single haptic, touch-sensitive display in vehicles that provides crucial controls for both the driver and the front passenger. With a single, simplified haptic display panel that controls everything from climate settings to infotainment, vehicle operators and passengers have less distractions and can better concentrate on the road. 

While such innovations have begun to roll out over the past few years, it will take time to become commonplace. TDK has worked with Boréas Technologies and Immersion to create a platform for next-generation of automotive console that provides all of the features normally found in a vehicle’s console. This platform can be used to springboard new innovation. 

Haptic Considerations

When selecting haptic devices, design engineers have several items to consider. 

First, there are currently no industry-wide haptic technology standards. As a result, supply chains, system integrations and designs are fragmented around a few manufacturers. Ensuring that the best-suited partner ecosystem is selected is crucial to the success of a haptic-centric design. 

Second, a system-level approach is required, which includes selecting an actuator, driver, microcontroller and middleware. Drivers may be required to detect and communicate this data back to a host controller while producing voltages as high as 150V to operate properly. In most cases, an inter-integrated circuit (iC2) or serial peripheral interface (SPI) would provide interface between the driver and the host controller. 

The third consideration is space. Electromagnetic haptic devices require a larger footprint than a piezo solution. It is also more limited in the types of haptic feedback it provides. However, smaller piezo devices may be more expensive than larger LRA or ERM devices. 

Finally, determining what feedback is required in the design is critical. For example, a seat that vibrates to warn a driver of a lane change may be accomplished with a larger, low-mass ERM or LRA object, whereas a touchscreen on a center console may require a miniaturized piezo actuator that produces several distinctive types of feedback.  

Miniature piezo haptic devices like TDK’s PowerHap™ are less than 1.5mm thick but can accelerate a mass of 100 grams at over 6 g. Actuators that are larger can accelerate a mass of 1200 grams at 12g. These devices are scalable and programmable to optimize acceleration and displacement based on mass and size of end product, making them ideal solutions for a wide variety of automotive applications. 

Future Feedback

In the future, growing numbers of vehicle systems will employ haptic feedback to provide the feel of tomorrow’s automobiles. With its unique product range of piezo haptic actuators in collaboration with its joint-venture partners, TDK can offer solutions suitable for all automotive haptic applications that allow users to anticipate and feel feedback from surfaces and displays designed for interaction. 

Through the use of piezo haptic actuators, drivers will have a better user experience and be able to intuitively feel of the controls of the car like a well-fitted glove for an experience like none other.

Sponsored by TDK