the key technology of automotive switches

Adaptive haptic technology is becoming more and more widely used in the automotive industry. Merritt's adaptive haptic multifunction knob is one of the projects that follows this trend.

Every day we press the button and turn the knob. The touch feedback force of some of the knobs makes us feel soft, and the touch feedback force of other knobs makes us feel heavy – these are our personal feelings. Through the sense of touch, we understand the relationship between the force and linear motion of the button, the torque and rotation of the knob.

Adaptive touch has a wide range of applications:

● Simulate virtual buttons on the touch screen;

● Simulate the surface roughness of different materials;

● Variable tactile feedback of the analog knob.

Keywords - adaptive, variable, adjustable.

The touch screen provides great flexibility in creating a human interface. The touch area can be placed anywhere on the screen, depending on the design.

Adaptive touch has a similar purpose. It eliminates the bondage - the change in touch does not depend on the reaction on the screen.

Simple human-computer interaction - adaptive haptic multi-function knob:

Today's cars have a lot of configurable settings. Merritt hopes that the car's cabin will not be as complicated as the airplane's cabin. This is why only one multi-function knob is used to configure all adjustable functions. Cars also typically have a central display that the user can select from a rich menu using a multi-function knob. Merritt's versatile adaptive haptic knobs provide a variety of customized touch feedback for different levels of menus.

Typically, the main menu contains very few options, whereas a single menu, such as a song list or a phone contact list, contains many options. Adaptive haptics help to handle these different usage scenarios. For example, in the main menu, the knob has 12 stable positions. In this case, the user needs to rotate a fairly large knob angle to achieve the next position. In turn, the precise selection of the menu function list is realized. For a list of tracks containing 100 songs, the knob requires more "clicks" (position) for each revolution. It is very helpful for users to get to the desired location quickly. The added bonus is that he can feel the changes that have just occurred in the list view.

Traditional solution for knob tactile feedback:

How do you usually implement the tactile feedback of the knob? The cam and latch are the two most important components. The most common is to lock the cam to the knob. The shape of the cam determines the number of slots - the stable position of the knob. The interaction between the cam and the latch produces a torque-to-angle characteristic - the sense of touch.

Merritt Adaptive Tactile Feedback Multi-Function Knob Solution:

Instead of cams and latches with motors and gearboxes, dedicated software generates torque versus angle plots (algorithms). Load adaptive feedback to the microcontroller to manage the entire knob. The position sensor measures the current position of the knob. The microcontroller calculates the torque value corresponding to each knob position (according to the torque versus angle graph). The microcontroller then adjusts the magnitude of the current output to the motor to produce the calculated torque value. All of the above detection, calculation, and execution are every few milliseconds, so the user feels that the touch is smooth and continuous.