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Whether it's a scorchingly hot day making you dizzy or a bitingly cold day, comfortable temperatures can always welcome you upon your return home. Such a dreamlike lifestyle is now easily achieved. By connecting your air conditioner at home to the network, you can operate it with your smartphone while you are out. And as you can also check your air conditioner's operating status, you no longer need to worry whether you forgot to switch it off. Such lifestyle convenience and comfort is supported by "connection technology" — through Hitachi.

(Publication: December 19, 2014)

Connecting for more convenience, more comfort

We are seeing many convenient functions in recent home appliances, aren't we?

Photo: MACHIDA Yoshihiro

MACHIDAYes, indeed, and Hitachi is also engaged in research activities to achieve more comfortable and easier-to-use products, let alone energy efficiency. More recently, we've witnessed the development of a growing number of "smart home appliances," allowing the advanced connectivity of such devices to remote networks. An example is a domestic-use air conditioner. By connecting it to the networks, you can now operate it using your smartphone while you're away from home.

IIMURONot only can you start or stop the operation of such an air conditioner, but you can also check its current status. You can use such functions with almost all Hitachi's recently-launched air conditioners in Japan.

Now we don't have to worry ourselves about whether we've left the air conditioner running or not. Can you explain how the system works?

SUENAGAThe system is not so complicated. As Figure 1 shows, when the user sends instructions from the relevant application on his or her smartphone, the information is sent to a dedicated server via the Internet. Subsequently, the dedicated server transfers these instructions to the air conditioner through a wireless LAN connection adapter, and the air conditioner performs the instructed operation. That's how the system works. The operation results are notified to the user through an e-mail.

Figure 1: Overview of the air conditioner remote control system

So, instructions are transmitted to the air conditioner via numerous devices?

MACHIDAExactly. To create this system, we asked for the cooperation of multiple companies in the Hitachi Group, as well as the business operations division producing air conditioners. As plans called for building the system within a short period of time, we generated various ideas—even at the designing stage—so that the system could be constructed smoothly.

Send instructions and receive confirmation by e-mail

What ideas did you generate?

MACHIDAThe first is a communication methods between smartphones and the wireless LAN connection adapter. Communication occurs using HTTPS protocol between smartphones and a dedicated server, and e-mail protocol between the dedicated server and wireless LAN connection adapter. These are both typical protocols and can be easily applied and tested.

In addition, the dedicated server needs only a web server function and mail server function. This is advantageous as the system can start small and can easily be expanded in the future if the number of users increase.

Figure 2: Communication methods between smartphones and the wireless LAN connection adapter

How interesting that a scheme where instructions and confirmations are sent by e-mail was used.

IIMUROYou may say so. Of course, we could utilize more complicated schemes or more advanced communication methods, and incorporate the latest technologies if we wanted to. However, that would inevitably increase the burden on the wireless LAN connection adapter, leading to larger power consumption. In order to save power while maintaining convenience, it is essential to employ an intermittent operation scheme, or a scheme that operates only when necessary and to the necessary extent. We therefore thought that e-mails would satisfy this requirement as they are are meant to operate at the time of receiving and sending.

MACHIDANotifying the operation results to users is also important from a safety perspective, as it should help avoid unintended operations. However, because communications are conducted via various equipment, there is an inevitable time lag.

The current specifications from the sending of instructions to receiving operation confirmation incur a time lag of about 5 minutes. It's unrealistic for users to keep watching their smartphones during this period, isn't it? We looked for a system in which operations confirmation is securely returned, even when the application is off, and one which could be used by anyone. We found e-mail to be most appropriate.

Did Yokohama Research Laboratory also work on developing the wireless LAN connection adapter?

MACHIDAThat's right. Mr. IIMURO was in charge of the base section, such as the hardware and operating system (OS), and Mr. SUENAGA handled the application section that operates on the base section. The application section had a half a year or so head start, as studies on its main technologies were already underway, but development of the base section had to be conducted almost in parallel with the construction of the system.

Two reasons why Linux was selected as the OS

How did you develop the base section of the wireless LAN connection adapter?

Photo: IIMURO Satoshi

IIMUROFirst, we selected hardware and software that met the requirements. Although the hardware is usually selected first, in our development we selected the software first.

This is because the wireless LAN connection adapter must conduct multiple operations simultaneously, such as sending and receiving e-mails while checking the status of the air conditioner, and it is more appropriate to have the OS perform such operations.

For a system with a size of the wireless LAN connection adapter, the OS known as ITRON is often used in Japan. However, we selected the Linux® OS because it facilitates incorporation of networking-related functions. It also provided us with another advantage of helping us shorten the development period as there was an abundant supply of open source libraries.

So each type of OS has its own advantages?

IIMUROThat is correct. As Linux is good at networking, it should be able to more easily cope with various types of communications going forward. So we selected a platform that can easily respond to system expansion in consideration of future development. As an example, the Linux-based platform can handle the HEMS (Home Energy Management System), which has increasing demand in the market, by partly modifying the software.

SUENAGAUsually, the biggest restriction comes from cost. Often, as a result of having already selected the hardware from the perspective of cost, you have to abandon the use of a high-function OS. In our development, however, we first selected the OS and so were able to use somewhat extravagant hardware.

Photo 1: Circuit board of the wireless
LAN connection adapter

IIMUROAbsolutely. For running the Linux, we used a microcomputer that is one notch above what is usually used, and we used a larger capacity of memory. They were a bit expensive, but we used them as the best possible choice after comprehensively considering their effects on shortening the development period and their expandability.

After selecting the hardware and software, we decided on how to incorporate them into a system and actually incorporate them to overcome each obstacle. Eventually, we prepared a circuit board as shown in Photo 1.

Does the application run on this circuit board?

SUENAGAThat's right. The application acts as the bridge for communications between different devices. As different types of devices may use different protocols to communicate, we incorporated two technologies to achieve accurate and smooth communications. One is the Protocol Translation Framework, and the other is the Network Low Layer Harmonized Control Technology.

Linux is a registered trademark or trade mark of Mr. Linus Torvalds in Japan and other countries.

Aiming to establish technologies that can be applied to a wide range of devices

Can you tell us about the two technologies incorporated into the application in more detail?

Figure 3: Scheme of communication processing
in the wireless LAN connection adapter

SUENAGAThe Protocol Translation Framework is a technique for converting protocols while absorbing the existing differences.

When there are different protocols, there are also large differences in the methods used to describe the communication content. In other words, they not only speak different languages but also speak in very different manners. For example, a protocol can express something in a single word, while another protocol may have to use multiple words to express the same thing.

The Protocol Translation Framework first converts the sender protocol to a common protocol, and then converts the common protocol to the receiver protocol. The common protocol serves as a "cushion" to absorb the differences in the way to express things.

The other one, the Network Low Layer Harmonized Control Technology, is a technology to synchronize the timing of communications.

For example, when you inquire if the air conditioner is in operation or not, you ask the air conditioner to tell you its present situation, but the air conditioner may sometimes not answer you immediately, saying "I'm busy now." Therefore, the technology lets the wireless LAN connection adapter, the bridge, remember what information you need and relay it to the air conditioner. By doing so, the exchange of information becomes possible at a time that is convenient for the respective parties.

This intermediary is important, isn't it?

Photo: SUENAGA Shinya

SUENAGACorrect. We could make a scheme in which the sender and the receiver communicate one-on-one, but it would lose versatility. In our latest development, the communication target was the home-use air conditioner. But there are many other types of home appliances. Moreover, such communications may have to be conducted with business-use equipment.

For example, business-use air conditioners are the same as home-use air conditioners in terms of being equipment for conditioning the air. However, their protocols for communications are completely different. If we create a one-on-one communication scheme for home-use air conditioners, it would not be applicable to business-use air conditioners. To operate the latter in the same way as the former, we must create one scheme that can incorporate different communication protocols.

IIMUROThere are many devices that have not been connected to networks, while there are devices that will become widespread, such as the "smart meters". So we thought we should aim to create a scheme that can be applied to as wide a variety of devices as possible, instead of specializing on certain devices.

SUENAGAOf course, we are not sure that the scheme is applicable to all devices for smooth communications. Depending on the device, we may have to modify it to some extent. We attempted to create what should work well with devices that could be assumed at the present time, and came up with the present scheme.

New approach for safety

Are there any other issues that you doggedly stuck to in the development?

Photo: MACHIDA Yoshihiro

MACHIDAI would say that we wanted to ensure safety with regard to operating equipment and devices from outside home, as such functions did not exist before. For home appliances, the technical standards under the Electrical Appliance and Materials Safety Act serve as a guide. However, when we started development, the standards on remote control were still under review. Hitachi was a participating member of the Remote Control Task Force that was in charge of the review and modification. So we were able to check the status of discussions at the Task Force as needed, and worked to incorporate the new schemes into the system.

IIMUROHitachi pays particular attention to safety, and has established its own safety standards. If there are any other standards other than its own, as was the case in this latest development, the product must clear both standards before being released to the market.

So, the products go through rigorous checks?

Photo: IIMURO Satoshi

IIMUROOf course. From now on, however, abiding by the standards is not enough. We must be able to prove that the products satisfy the standards. This is based on the idea of "functional safety," which commands that it is the responsibility of the companies to prove that their products are manufacturered to be safe for use.

MACHIDAThere are international standards for functional safety. In Japan, the relevant standard is currently for areas directly related to human life, such as robots working in factories and the brakes of trains. But plans are that the scope of these standards will expand to home appliances by around 2016 or so.

IIMUROOur division is also focusing on functional safety as we conduct research recently. Proving safety doesn't mean we always have to take special measures. One of the methods is to prepare programs in a neatly arranged manner even at the development stage, because clumsy programs don't allow you to quickly check if they are safe or not. If programs are prepared neatly, they naturally enhance development efficiency. So we believe that safety is achieved based on and as a result of continuous, daily endeavors for improving products.

Are you saying that things that do not look related to each other may in fact be linked and correlated?

Photo: SUENAGA Shinya

IIMUROYes, I think so. I am currently involved in investigating a certain system to be installed in products in areas far removed from air conditioners. Despite the differences in the products, it is the same in the sense that the system uses a microcomputer and selects a certain OS. I wold like to continue studying systems for products of various areas by taking advantage of the knowledge and expertise obtained through the development of the wireless LAN connection adapter.

SUENAGAI want to pursue finding how things can be connected with each other, and make attempts to develop connecting methods and create connection schemes. It's not only about devices alone but also, for example, about connecting with computing resources such as the use of "clouds."

MACHIDAI would also like to consider the joy of being connected. What value can we provide users by having products connected? Although we are somewhat working in the dark, I hope to create new value that has never been available before.


  • Publication: December 19, 2014
  • Professional affiliation and official position are at the time of publication.
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