What is an HMI?
HMI or Human Machine Interface refers to the touchpoints of any device which a user interacts with to control a device.
Simply put it is where the user gives any commands (inputs) and receives feedback on information (output). For example, a desktop PC. The monitor gives you visual information, speakers give auditory information, and your keyboard and mouse both give you methods of input, one for your cursor and one for the text. Even something as small as an LED on your keyboard gives you visual information. All of these combine to give a holistic Human Machine Interface.
Smartphones have simplified this to have a touch screen to provide a single touchpoint for a majority of your input and output. In addition to audio and a few LEDs, smartphones use another form of feedback through haptics. Based on the context, using multiple senses, sight, hearing, and touch can make your interface more intuitive. Maybe in the future, we can engage the other senses.
HMIs in Modern Consumer Appliances
All of us have come in contact with some form of an HMI. Whether it is a control panel for a washing machine or a microwave oven, we have all used good and bad versions of HMIs. As Industrial Designers, UX Designers, or anyone who is tasked with creating an HMI for a consumer appliance, it may seem like a simple task. Finding multiple articles on how to test your mobile or web experience with users is easy but far fewer exist for testing the HMI. While these articles often cover testing with different user personas/groups, they fail to cover an extremely key point - Context.
Context is the Key
What is the context when it comes to consumer electronics? It is everything from the room the user is using the product, to the time of day, and different use cases of your product. How would an HMI change for an induction cooktop when it is used indoors vs used outside on a sunny day? Understanding this context is extremely important before starting your design.
As your design is starting, you should be getting a clear idea of the use cases, user personas, and environments in which your future product may be used.
Mistakes are only natural and everyone makes their fair share of them. We will outline our learnings in Part 2.