As a result the interactive interface in cars has become more complex. How should we design HMI, an important part of user-vehicle interaction?

In-vehicle interactive design includes hard interaction and soft interaction. Hard interaction refers to operations of the driver, which shall be carefully designed. For example, the driver can change the position of the driver's seat by pressing a button, or enter a POI into the satellite navigation system through GUI and then activate the in-vehicle entertainment system.

Soft interaction refers to machine operations, such as automatic deactivation of the turn light signal, which is carried out by the machine rather than by the user. Soft interaction highlights the role of built-in sensors and the concept of vehicle connectivity, for example, display of relevant information through HUD, automatic adjustment of illumination, and automatically checking whether the driver has closed his/her eyes. Besides, there is a clear boundary between assist and distraction, so soft interaction requires great maintenance and proper execution. According to PATEO design team, the key to HMI design is to combine hard and soft interaction.

Thus, HMI design is aimed not only to help users conduct simple operations, but also to meet potential demands (i.e. reasonable demands) of the driver and passengers while on the road on the condition of guaranteed safety. Complicated HMI design and limited memory capacity of human beings may impose extra burden on users. As a result, HMI design shall also minimize distraction of the driver's attention and possibility of making mistakes by reducing the use of distracting devices (e.g. mobile phone) to the largest extent.