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Connecting humans to technology: A look at Human-Machine Interference

Saturday, July 1, 2017 - 07:00
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If you ever get the chance to see a good car movie, then check out the movie American Graffiti. Many of you who grew up in that era may remember what it was like to drive your car while listening to your human machine interface (HMI). Sometimes it’s referred to as an (HIM) or Human Interface Module. Ok, I know what you’re thinking. He must be talking about the radio or he’s gone off the deep end. So let’s have a brief history lesson so I can make some sense of this crazy nonsense.

The beginning

Back in 1930, the Galvin Brothers installed the first commercially successful car radio in the Model A for an expensive option of $540. It was the first product to wear the Motorola name. Since then, motor vehicles have evolved with the changes in technology as the years have progressed. In 1952 the FM radio was introduced, and in 1953 many manufacturers offered an upscale radio with both AM and FM.

In 1955, the first music “on demand” was offered by Chrysler in the form of a turntable installed in the vehicle. It played seven-inch records while driving down the road! Naturally it was a bust. In 1965 the first 8-track players were in production; 1970 saw the release of the cassette player, and finally in 1985 we saw the advent of the CD player. In 30 years the car radio has evolved into a sophisticated, computerized central intelligence module that the driver uses to incorporate his or her entertainment and/or infotainment choices while driving. The term HMI means the interaction of the human being to make a change or selection to the module that controls our entertainment.

Figure 1

Way back in the day, nobody referred to the car radio as an HMI or HIM, but we as humans did interact with the radio in the fact that when we wanted a change, we adjusted the knob to select another station or we changed that cassette tape if we wanted to hear a different song. It’s the same kind of principal today as it was back then, only today there are a lot more electronics and technological changes that take place that we as vehicle owners are not aware of. So let’s fast forward to 2017 and look at some of the electronics that play a part in our entertainment and our infotainment systems. We will focus on the 2017 Chevrolet Silverado (Fig. 1) as our vehicle in this discussion.

Entertainment vs. infotainment

Entertainment is designed to give pleasure like listening to music. Infotainment is the programming that gives information which then in turn gives entertainment. For example, a GPS system or Global Positioning System. Some of the electronics in a modern day entertainment or infotainment system consist of a stereo radio, a navigation system, a universal serial bus (USB) system, a cellular phone system, speech recognition system, Bluetooth systems and others (Figs. 2, 3). These different systems work on a data bus line known as the MOST (Media Oriented Systems Transport) network. It is a high-speed network that communicates with the GMLAN network. The radio in this system is considered the bus master or gateway as its sometimes referred to. Let’s take a closer look.

Figure 2 Figure 3

The HMI is the component that is responsible for the video in the display screen. It’s called an HMI because it is a video touch screen display screen that works as the interface between human and system (hence the name) (Fig. 4). The HMI works in conjunction with the instrument panel cluster (IPC) and the radio. The HMI module communicates with the infotainment display module via the Local Interconnect Network (LIN) bus network for control communications, touch communications and the dimming or brightness of the display itself. The LIN network is a single wire used to transmit information between a module master and other smart devices. Digital data that’s in the form of a video is sent on a dedicated video cable.

Figure 4
Figure 5

So, how does all this work? Your radio is in constant communication with your HMI module and is ready to interact with your touch commands, voice commands, Bluetooth communications and even a USB memory card reader — yes, the same as one that’s in your home PC. The HMI actually has three different networking systems that connect to it: the GMLAN, or GM local area network, the MOST network and the LIN bus network. That is why it’s called the bus master (Fig. 5).

When things go wrong
Go about your diagnosis just like you would any other network problem. The important thing to remember is to make sure you know what players are involved in the system you’re working on. There are a lot of different combinations that are offered for this vehicle and some of the options might not be there. A service information system along with a GM option code index are a couple of the essential tools you will need.

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