Active RFID Real Time Location System by Zoning

Real time location tracking can be done either by triangulation or by zoning. The former method makes use of sophisticated algorithms to locate the RFID tag based on comparing the readings of three or more readers while the latter one is done by dividing areas into zones, allocating a reader to each zone and tuning its gain in order to detect only tags in the said zones.

 

What is zoning method?

 

By dividing the area into different zones and installing readers at each zone, tags can be detected when entering a specific zone. With a list of records on which tag being read by which reader, the system is able to identify the location of the tag. This is how the zoning method works for real time location tracking.

 

Tuning of readers of zoning method:

 

Tuning of readers during installation takes an important role in zoning method. It allows precise and stable reading of readers in specific zones.

 

For example, even if a tag is positioned close to the wall and could also be detected by the reader in the adjacent room, the tag is still considered located in the correct zone. The signal from the tag is stronger for the reader in the room but weaker for the reader in the next room to detect. With such feature, zone level locating accuracy is performed excellently.

 

Using the zoning method for RFID real time location tracking has the following advantages:

•  High zone level reading accuracy of up to approximately 99% with developed software
•  Less affected by indoor obstacles like partitions
•  Suitable for both people and assets locating
•  Cost effective compared to other RFID real time location tracking methods
•  Less power is required compared to location tracking with Wi-Fi system

What is triangulation?

 

The triangulation method compares the readings from three or more readers in an area using sophisticated algorithms. There are two types of triangulation methods, Relative Signal Strength Intensity (RSSI) and Time Difference on Arrival (TDOA).

 

Principle: Location coordinate system for triangulation

 

Consider the coordinates system for location. During initial installation, coordinates of three or more readers are recorded. When the tag is inside the area, signal of the tag is received by all the readers in the area, with different signal strength or arrival time of signals. Location of the tag is then measured by solving the set of equations.

 

Wi-Fi tags method used by some companies is also a kind of RSSI triangulation. Special network access points for reading and transmitting the measurement of the signal strength are used instead of readers in the area.

 

Applying triangulation for location tracking may have inaccurate results especially in indoor areas. Inaccuracies occur mainly due to:

•  Variation of sensitivities of commercial readers
•  Non-identical reflection in the beam passage towards each one of the reader
•  Direct and reflected beam of radio waves may create destructive interferences when they meet each other
•  Tag does not emit signal uniformly to a range of 360˚
•  For indoor applications, presence of partitions reduces intensity of signal compared to a direct path without any obstacles

Other than inaccuracy problem, the major disadvantage of a TDOA system is its high cost due to the following reasons:

•  The readers must use expensive internal crystal clocks
•  More than three readers must be used in order to get a reasonably accurate result even in a small area, such as 20m x 20m
•  Complex tuning procedures may be required for accurate readings
•  Ultra-wide band may be used to improve the range of detection by using short pulses over a broader spectral range
•  For indoor applications, at least four synchronized readers must be used to cover approximately 15 rooms

Comparing Zoning and Triangulation

 

Though accuracy of zoning method when used in outdoor environments is reduced mainly due to the reflection and orientation of tags, in comparison to all the methods that we have reviewed, it is clear beyond any doubt that it is still the most suited approach for indoor applications, where room-level accuracy location tracking is required. Reasons are the following.

 

• Significantly lower installation and maintenance cost with the same level of performance

 

• Significantly higher accuracy

 

• Higher stability of reading

 

• Simple installation

 

UHF laundry tag launched

Correctly identifying and classifying batches of clothes after washing in an industrial washer; preventing towels and linens from stolen and making sure the same batch of laundry is returned from the washing facilities are all challenges that hospitals, hotels and restaurant chains are facing in managing their high volume laundry.

HK-RFID’s laundry tag is specially designed for applications requiring a rugged transponder that can withstand harsh environment with heat, pressure and chemicals during the washing process. The laundry tag is waterproof, chemical and heat resistant and can withstand temperatures up to 200 degrees.

The RFID laundry tag comes in two frequencies: high frequency (HF) and ultra-high frequency (UHF), accommodating different project needs. UHF laundry tags offer a longer read range while HF tags are more commonly used. The anti-collision ability for the laundry tag enables reading of up to 50 tags per second.


The RFID laundry tag can be reused for more than 1,000 times and the EMS memory of this tag can be wiped and written for more than 100,000 times. Tags are offered in different sizes with one, two or no hole for affixing to linens or towels by sewing, gluing, or other methods.

Joining the Mid-Autumn Festival Volunteer Program of Lok Sin Tong Benevolent Society, Kowloon

Oct 2011

On 10th September, a team of volunteers from our company joined the Mid-Autumn Festival Volunteer Program of the Lok Sin Tong Benevolent Society, Kowloon, visiting the elderlies and low-income families in Tai Kok Tsui and distributing mooncakes to them. The Lok Sin Tong Benevolent Society, Kowloon is a non-profit organization serving the public with quality and diversified educational, medical and social services to communities in Kowloon, Hong Kong.


Staff was divided into teams and visited different families in the community bringing them mooncakes that day. They enjoyed the activity and regarded it a meaningful Mid-Autumn Festival. Apart from business development, our company always encourages our staff to join different kinds of voluntary activities in order to give back to society.

It was not the first time for us to participate in voluntary work. Every year, we join different kinds of activities organized by charities not only to take an active role to care about our society, but to help developing a balanced lifestyle for our staff. It is our belief that only by the growth and development of us and our staff in every aspect would offer us a successful future. Hong Kong RFID Ltd. aims at continuing its business as a socially-responsible and sustainable company.

RFID in automotive industry - Traffic Management System

RFID in automotive industry

Traffic Management System

Case Study

Hong Kong RFID Ltd. developed a RFID traffic management system offering efficient and accurate vehicle management solution. RFID system has long been used in automotive industry in countries like Brazil, Dubai, India, China and Mexico.

 

RFID readers are installed at main traffic intersections or alongside roadways.

RFID cards are placed at the front of automotives using a card holder. Each RFID card contains a unique card ID which is associated with information in the back-end database upon registration. Useful information can be stored in the database to suit operators’ needs for various systems.

Readers at roadsides read the RFID cards in automotives when they are moving in high speed. Card ID is then identified and information retrieved from the database would be shown in monitoring centre. With accurate time, reader and card information, specific automotives are tracked and recorded easily.

RFID Traffic Management System

Traditional vehicle monitoring systems uses surveillance cameras to scan automotives’ license plate for identification. However, usually less than 50% of the license plates can be scanned clearly, leading to insufficient record for automotive tracking.

Applying RFID in traffic management systems in place of traditional system provides much higher accuracy, efficiency and convenience for both operators and drivers.

l   Non-stopping identification

Readers at roadsides detect the RFID card and record the ID as soon as automotives pass by. The whole process is automatic and instant without any interference to traffic system.

l   High speed reading

Capability to read moving automotives of speed up to 150km/h allows application of the system on highways. Any prohibited speeding behavior is detected and recorded as well.

l   Bad weather reading

RFID system uses radio waves for communication between readers and tags. Any bad weather conditions will not affect the performance of the system, ensuring its accuracy.

 

Handheld readers are used in associate with fixed readers at roadsides for individual traffic spot tracking.

Stationary reader used in automotive industry for traffic management purposes.

Benefits:

The traffic management system enhances management process of automotives with:

l   Higher reading accuracy

l   Higher efficiency in overall operation flow

l   Reduction of human resources in case of emergency or malfunction

l   Time-saving due to automation

l   Convenience for both operators and drivers

l   Better management of traffic system

Active RFID solutions for Construction Site Safety

Active RFID solutions for Construction Site Safety

RFID alarming and tracking system

Case Study

Active RFID tags, each with a unique ID, are attached on construction workers’ helmet. Since the helmet has to be worn at all times when inside the construction site, the tags are carried around by the workers at all times also.

Benefits:

l   Ensure safety of workers in construction site

l   Better staff management

l   Higher labor efficiency and productivity

l   Higher visibility of operation flow

l   Reduced human errors in manual recording system

l   Increased capability utilization

l   Better planning and use of resources

Personal Warning System

Active RFID personal warning system prevents unauthorized access to dangerous areas in the construction site, avoiding accidents caused by incautious workers.

When a worker is trying to enter the dangerous zone, readers at the entrance of the zone detect presence of tags on his helmet. The buzzer built-in with the tag will emit alarming sounds to warn the worker. The operators in the site office would also be informed with a warning message shown on a PC or LED display..

 

Real-time Location Tracking System

Active RFID system provides real time location tracking of workers in different zones of the construction site, providing information for central office to enhance staff management.

 

l   Attendance record of workers

Active readers are installed at the entrance of the construction site. Attendance of workers are recorded automatically when workers walk through the entrance and enter the site with their helmets. Manual system for signing in and out is not needed anymore, overall efficiency and accuracy is enhanced.

Arrangement of two readers for distinguishing workers’ check-in or out records.

l   Location tracking in construction zone

Active RFID system has reading range up to several dozen meters radius. Readers are installed in various zones for full coverage of the construction site. When the worker walk along the site, readers keep detecting the signal from the tag. Such signal is sent to the central office every second, performing a real time location tracking function for all the workers.

l   Staff management at central office

Readers installed at entrances detect the entry of workers into specific zones. When workers are inside a zone, a PC/LED display at central office shows the information of each worker, including name, ID number, registration data and any other useful information. The central office can better monitor the allocation of workers to each zone more efficiently.