Parikshit Basrur & David Parry,
Auckland University of Technology, New Zealand
dparry@aut.ac.nz
 

Basrur, P & Parry, D. (2006, October), “Where are my Glasses?”: An Object Location System within the Home. Bulletinof Applied Computing and Information Technology Vol. 4, Issue 2. ISSN 1176-4120. Retrieved from

ABSTRACT

“Assisted living” refers to technologies and techniques that support elderly or disabled people in their homes. As the percentage of elderly people in the population increases, the economic and social importance of such systems increases. One common experience of aging is the increasing difficulty of remembering exactly where household objects are located. The aim of this work is to propose a system to support the location of easily-lost (“losable”) objects) in a dynamic home environment.

Radio Frequency ID (RFID) technology involves the use of very cheap uniquely identifiable tags which can be interrogated from a short distance without a line of site. This project proposes tagging household objects with the tags, as well as geographically important locations within the home. The user is equipped with a portable PDA-based tag interrogator. This device records a list of tags within range and hence records a list of locations visited as well as the picking-up and dropping off of the easily-lost objects. When an item is required the user communicates with the system via a voice recognition interface and the system replies with the nearest geographical locations of the dropped off item along with the time that the item was dropped. Should this not be sufficient to locate the item, the user could also be provided with a trail description - a list of locations and times) which may be mapped to common tasks and activities such as making breakfast. If a short range search is required the system could support a set of search patterns borrowed from avalanche transceiver techniques. Issues with the learning and data storage requirements of such a system are discussed.

Keywords

Assisted living, radio frequency ID, RFID

1. INTRODUCTION

One of the major challenges facing developed nations in the early 21st Century is the change in the demographic make-up of society. Increased expected lifespan and a reduction in the birth-rate imply a large increase in the number of people older than 65. This situation is further compounded in New Zealand, by the large number of the young working people moving overseas for their “overseas experience”. Data from Statistics New Zealand ( Statistics New Zealand, 2005 #31) based on the “medium” assumption of changes until 2051 is shown in Figure 1.

Figure 1: Demographic Changes in New Zealand (Statistics New Zealand, 2005)

As part of the response to this challenge a number of research projects around the world are attempting to assist elderly and disabled people in their everyday activities and the so called “Aging in place” (seniorresource.com, 2005 #33) . These efforts are wide ranging and include  support for remote physiological monitoring and emergency alarms, reminder systems, support for people with impaired mobility, or memory  and for those suffering from sensory problems such as deafness, and loss of visual acuity (Cheek, 2005 #34) .   The drivers for such developments are not entirely altruistic, healthcare costs associated with elderly care outside the home may become extremely important, and older people are often relatively wealthy thus providing a market for assistive devices in both the public and private sectors.

 One of the most recent movements in computing has been the move to pervasive or ubiquitous computing. Mark Weiser is often identified as the father of this movement with publications (Weiser, 1993 #4) that challenged the community to produce ”invisible” computing - that is to say networks of devices that support human activities that do not  get in the way of such activities. Improvements in processing power and battery life and the drop in the cost of sensors and wireless networks have started to make such plans more practicable. In particular the increase in availability and reduction in price of  ”consumer electronics” devices, such as personal stereos, mobile phones, Ipods and game consoles, along with the increasing prevalence of home computers have  encouraged innovative design for the cheapness, robustness and capacity of such devices.

The concept of the “intelligent home” is not particularly new,  Stauffer (1991) describes a “Smart House”, including a network for home automation. More recently work has been done on the use of instrumented houses as technology test beds (Helal, 2005 #12) , and there has been increasing recognition that networking and computer control of electronic devices in the home is only one element of a solution for a supportive environment . A recent paper (Stefanov, 2004 #39) , gives an overview of some of these requirements. Appropriate interface design, context-awareness, standards for interoperability and most importantly usefulness are necessary for success.

Interfaces for supportive environments have to be useable by the intended beneficiaries. If the potential user is likely to have deteriorating eyesight, arthritis or limited keyboard skills then voice activated systems that are always available to the user seem appropriate. A simple implementation of this would be a PDA or mobile phone that is carried in a pocket or pouch.

In terms of context-awareness one of the most important issues that is often overlooked is the difference between the home environment and that of the workplace. Studies of home environments (Mateas #37; Rode #3159) have demonstrated the fact that use of devices in the home is essentially collaborative, and part of a continuous process, rather than the individual, task-based activity common in the study of workplace-based activity. This means that devices are often shared, and that approaches that require the exclusive use of shared items such as the television by a single user are unlikely to be acceptable.

Interoperability standards range from hardware and electromagnetic frequency standards to higher level standards such as device description and communication protocols. Usefulness demands that the system answers a real need rather than being seen as a  means of  selling new technology, or making already complex technology even more so. Finding objects in the home is a task that everyone performs.  Memory failure is a common problem in the elderly with 25-50% of people reporting it (Cees Jonker, 2000 #41) . A system to assist with finding objects in the home may therefore be useful.

2. SOLUTION DESCRIPTION

There are a number of ways of locating objects. Essentially the object location problem requires the recording of the object’s location in relation to some sort of frame of reference, which can be stored in a computer. Global Positioning System (GPS) receivers are capable of locating their position to within around 10 metres on a worldwide scale in good conditions. However GPS systems are difficult to use within buildings, because of difficulties associated with reflection and attenuation with walls etc. In addition, unless a detailed internal map of the building is available, the location given is not relevant to local landmarks, and even the room may not be identifiable. Location within buildings requires varying precision, with scales ranging from room-level resolution to identification of adjacent objects. This problem has been addressed in city -level navigation, by using additional wireless sources such as cell phone cell ID’s  and local Wi-Fi hotspots (Borriello, 2005 #44) . The location of the receiver can then be derived by triangulation, by calculating which RF sources would be detectable at different potential locations in conjunction with a detailed map, and using this process in reverse for finding current location in relation to the map. If a history of locations, and especially known landmarks is held then this assists with the resolution of ambiguous location results. The user can also identify the nearest landmark, and if visible, can identify their current position exactly. This is useful in the case of an interruption of reception, where disorientation may occur.

Radio Frequency ID (RFID) Tags are small electronic devices that may be passive, that is energised by the Radio Frequency Radiation of the reader, or contain their own batteries (active). Passive Tags are extremely cheap, less than $1(NZ) per tag. When they come within range of an active reading device, they will be detected and a unique identification number received by the reader. The dictation device is active and handheld and PC compatible versions are available.  “Interrogator” is actually a more accurate term for this device as it initiates the dialog. RFID tags do not need a line of sight to the Interrogator and multiple tags can be Interrogated effectively simultaneously, however as with all radio frequency devices, range and reliability of reception is influenced by the presence of conducting material and interference from other sources. 13.5 MHz passive tags can be reliably interrogated at around 10-50cm depending on the aerial attached to the tag -usually on a printed label and the orientation and power output of the Interrogator. Aside from a factory-assigned unique ID, some tags have small amounts of memory available which can be written and read by suitable interrogation devices.

RFID tags have been used to enhance the study of daily living activities as part of video analysis (Mihailidis, 2004 #13) . Indoor object location and navigation support for assisted living is an area of active research. A recent technical report (M.-Y. Nam, 2006 #3155) describes a system incorporating RFID and ultrasound transducers. Previous work in this area includes the LANDMARC system (Lionel, 2004 #3154) which used active tags and a robotic navigation support system (Kulyukin, 2004 #3153) using RFID for landmarks. Many of the principles of this work are similar - however our approach differs in two main ways. Firstly by using only RFID sensors and small computing devices, the cost should be minimised, and the system is simpler. Secondly the use of RFID on both landmarks and movable objects means that actual location of the user is not the primary focus of the system rather, the relative location of landmarks and easily-lost (“losable”) objects is the main objective. This allows the system to be extremely flexible in terms of number of objects, number of users and in the addition of new landmarks to increase system resolution in critical areas.

 Other more complex systems such as that described in (Smith, 2005 #22) have attempted to increase the information produced by RFID tags by adding motion detection.

A system design for the location of lost objects within the home would have the following characteristics:

1. It should be relatively cheap.
2. Lost objects should not have to be modified greatly.
3. It should support multiple ways of searching.
4. Interface  and interaction should be intuitive.
5. It must survive a reasonable degree of home rearrangement.
6. It should not interfere with other occupants’ lifestyle.

The scheme described in this paper uses a portable RFID interrogator associated with a voice recognition system and database. Objects that may be lost (“losable” objects) are labelled with RFID Tags as are landmarks in the household. Because passive tags are used, a large number may be placed in different locations at little cost.

2.1 System Description

Initially easily-lost objects (LO) and landmarks are labelled with RFID tags. A database in the interrogator system allows association between the Tag ID and the description.  For each Tag ID a description that can be spoken and understood by the user is recorded. In choosing locations for landmarks the user should have a higher density of landmarks near likely locations of loss  as well as a regular pattern identifying navigation landmarks such as doorways, stairs etc. See Figure 2 for a potential scheme. It may be useful to give such high-level navigation tags high visibility colours so that they can be identified. Generally high-level navigation landmarks will require longer range detection, so tags with larger aerials may be used. The approach is similar to that of (Satoh, 2004 #16) , where the  “aura” component represents the final location of the object.

Figure 2. RFID Tag Placing

 When the user is holding the easily-lost object the interrogator registers the presence of the object and records the high-level navigation tags that the user passes. The tag ID and datestamp are recorded in the database. Interrogation happens at around 10 millisecond intervals, depending on the number of tags within range. In order to reduce storage requirements, the time of first detection of a tag and the time of last detection of a tag only, are stored for each tag detection episode. This avoids large amounts of data being stored when the user is stationary, or holding an object.

When the user drops the LO, then the system detects this by noting the absence of the LO’s tag ID in the input stream.  Any other navigation tags being detected at this point are noted.

When the user wishes to recover the LO, he or she names the object verbally and the speech conversion system finds the nearest LO name. Should the sytem not be able to resolve the name, it can ask for clarification. Such a dialog may be implemented in voiceXML.

When the required LO is identified the database is searched via the timestamps, radiating outwards from the time that the LO was last detected. The navigation locations that were detected at the closest point to the dropping of the LO are declared. Should this not be clear a dialogue could continue, with other nearby navigation points being declared until the user is satisfied that he or she knows the location.

When the user gets to the nearest navigation point they can begin a detailed search for the LO. Patterns such as those used in Avalanche search may be useful. Another alternative is to retrace steps, where the system declares the sequence of navigation points around the time before and after the LO is dropped. See Figure 3 for the details of the process.

Figure 3. Data Analysis and Storage

3. IMPLEMENTATION PLAN

 The system is yet to be implemented. Currently the combination of IPAQ pocket PC (Hewlett-Packard) and V720S (Omron) Interrogator appears practical and is relatively light (Figure 4). The RFID interrogator uses the CF port to communicate with the IPAQ, by simulating a serial device. Visual Studio (Microsoft) supports Pocket PC development and emulation and there are Pocket PC versions of SQL server databases available. Issues that may arise include detection range of the tags in varying conditions, usability and possible interference issues. The initial plan is to implement a system in a simple single room environment, to perform observational usability studies.

Figure 4. The IPAQ and RFID Reader

4. DISCUSSION AND CONCLUSION

Simple aids for daily living activities are extremely important. Flexibility in use is vital if the solutions are to continue to be used. One of the attractive aspects of the use of this system is the degree to which the system is flexible - for example if tagged navigation points are moved, then the system can still be used, although in the immediate transition problems may occur. By allowing the user to choose the spoken name for each location the system allows the geographical map of the building to be aligned with the mental map that the user has of the building. In addition by using small and relatively inexpensive markers, the user can increase the resolution of the system as required, for example marking each draw or shelf in a sideboard. There is also no limit to the number of items that can be found in one search, and items within items - for example, “are my glasses in my handbag?” - can also be located.

REFERENCES

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Copyright © 2006 Parikshit Basrur and David Parry,
The author(s) assign to NACCQ and educational non-profit institutions a non-exclusive licence to use this document for personal use and in courses of instruction provided that the article is used in full and this copyright statement is reproduced. The author(s) also grant a non-exclusive licence to NACCQ to publish this document in full on the World Wide Web (prime sites and mirrors) and in printed form within the Bulletin of Applied Computing and Information Technology. Authors retain their individual intellectual property rights.

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