544

QUESTION 3
Figure 3.2 shows a warehouse gateway which has already installed an RFID system to record down all inventory transactions automatically. The forklift passing though the gateway is at constant speed, and the carton boxes on the forklift are tagged with RFID tag. There are 3 paths that a forklift can pass though the gateway:

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Path A: Close to the antenna;

Path B: In a distance to the antenna; and

Path C: Far from the antenna.

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3i) According to the experiments of TPA and IZA, which one of the path do you suggest the forklift to follow with? Explain your suggestion with reasons.
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Recommended Answer for 3(i):
As noted, the interrogation zone (it is also said to be read zone or reader field) is the area in which a RFID antenna can provide enough energy to request and receive responses from the RFID tag, while RFID tags outside the interrogation zone can not receive enough energy from the RFID antenna to reflect back a response. As shown in Figure 3.2 above, there are 3 different paths, Path A, Path B and Path C. The Path C seems to be a good path for the forklift operator; this path has a wider radiation beam compared to the path A and B, however passive tag which is powered by electromagnetic waves energy from the reader and the effective read zone is subject to which type of RFID tag to be adopted.

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The following information being extracted from the ISE544 lecture notes (RFID fundamental- Components of RFID system) can help to provide more logical assumptions to this question.
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(Power for the tag)
Type of RFID Tags:

Passive Tag,

Active Tag and

Semi-Active Tag

Power Source:

Passive Tag from Reader

Semi-active Tag from Reader & Battery
Active Tag from Battery

Effective Read Distance:

Passive Tag= 3-5 M

Semi-Active Tag=100M

Active Tag= Not more than 50M

Power Required from Reader:

Passive Tag= High

Semi-Active Tag= Less

Active Tag= Less

Cost /Memory:

Passive Tag= Cheap / Least

Semi-Active Tag= High / Most

Active Tag= High / Moderate

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(Frequency Band and Cost)

Frequency of RFID Tags:

Low Frequency LW tag,High Frequency HW tag & Ultra High Frequency UHF tag

Frequency Band:

Lw= 125KHz, HW=13.56MHz, & UHF=915MHz
Tag Cost:
Lw=US$5, HW=US$2, & UHF=US$0.1
Read Range

Lw=0.5M, HW=Less than 1M, & UHF=3M

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Assumption:

Cost and Performance

In general, tag users are the most likely to choose passive tag as it is smaller, lighter and less experience, and this type of tag almost is unlimited life. Unlike the active and semi-passive tags, passive tag does not require internal battery as power source, so that why it is very popular and is widely used in warehouse management system. Apart from this, RFID tag with Ultra High Frequency can be considered to put into this question, its tag cost is quite low (it is US$0.1) compared with LW and HW tag prices, effective read range of UHF is the longer one, it can be detected within a distance of 3 meter long (see Table 3iB).

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Environmental Factor

To capture the existing figure, the width of the forklift is assumed to be 0.9M wide, and the clear width of the warehouse’s entrance is assumed to have 3.9M. (Logical Assumption: see the orange detect zoom, the width of clear opening seems to be equal of the sum of the total length of 7.8 squares (each 500mm is assumed, 7.8 x 0.5M = 3.9M))

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If UHF passive tags are now adopted in this warehouse and tagged on all carton boxes of each pallet, the forklift passing through the gateway along path C, the antenna’s energy is most effective due to a wider radiation wave in this path, but path C exceeds the limited read zone of the UHF tags which has just a 3-meter-distance to receive signals from the antennas. Therefore Path C is not an optimal pathway.

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As well, Path A is not a good passageway, this path experiences a small diameter of the radiation beam which sends from the circular polarized antenna, the response time in this path is very short due to the RFID antenna can not provide a wide angle of coverage with the tags, for those tags that are outside the interrogation zone or before entering this zone can not receive energy to reflect back signals.

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As for path B, it is moderate and it seems to be a likely pathway to the forklift operator, tags on the carton boxes from the antenna is less than 3 meters, and its coverage area is better than path A. For these reasons and all constraints, I will suggest Path B to the forklift operator.

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QUESTION 4

ABC Ltd is a company which produces electronic consumer products. Their products can be packed into regular-shaped carton boxes. The company considers installing an RFID system on the gateway of their warehouse to record down all inventory transactions automatically. Considering the investment budgets, the company decides to implement of the RFID system on carton-box level. The company plans to use passive RFID Tags, with frequency of UHF, and standard of EPC Class 1 Gen 2 Tags.

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All movement of the products that pass through the gateway is done by forklift. One pallet handled by the forklift contains 4 layers of carton boxes, and 1 layer contains 4 carton boxes. The warehouse of the company only has one gateway for products movement (See above Figure)

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4i) Design an RFID system for this company and give the rationale of your design. (Hints: An RFID Reader is around HK$15,000; an antenna is around HK$2,000; an orientation-insensitive RFID tag is HK$3; an orientation-sensitive RFID tag is HK$2. Your answer should include: The antennas’ setting, the type of tags to be used, the position and orientation of the tags on the carton boxes, the system’s performance. You should analyze the surrounding of the gateway and give your reasons for such a design. You also need to include the budget, i.e. the direct cost of hardware, the indirect cost for system development and installment. Add any other factors you may consider.)

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Recommended Answer for 4(i):

Overview of ABC Ltd ABC Ltd. deals with thousands of goods entering and leaving their warehouse, all of these goods enter the warehouse at one major access point where it is checked, the company considers installing an RFID system on the gateway to record the electronic product name, its date of manufacture, date of expiry and quantity.

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The problem with the actual daily operation is that there are thousands of goods entering and leaving the warehouse every day. Goods entering and leaving the warehouse are often stacked in huge piles and the scanning operators have to climb up the piles to scan the products to provide a complete and reliable record. The operators have recorded several complaints to the management concerning the huge piles of goods entering the warehouse and the difficulty in scanning all the goods at both ends. Many accidents in the past have also been noted and the management had to cover financial charges for the concerned personnel.

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Ways to solve the current problem

To deal with the problem, ABC Ltd proposed possible solution that would consist of the following:

• Provide the warehouse with a RFID scanning device at both ends to scan the goods entering and leaving the premises.


• Record the scanning details automatically and provide printouts for the management.

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This solution will at first reduce the lag-time caused by the actual operation and will also be consequent in reducing excess labor.

ABC’s expectation to the desired RFID system

• Facilitate the warehouse operators scan the goods entering and leaving the warehouse.


• Improve the current stock control, monitoring and management of the goods in the warehouses using the RFID technology.


• Provide for better and quicker reporting mechanism.


• Reduce cost in terms of man power on the long run.


• Decrease risk of loss and theft in the stock in the warehouse, actually some electronic products are high-price products.


• Reduce processing time for input of goods in the system and creation of in/out-flows data.
  

System Development

1. Installation of 2 RFID readers with antenna on the both sides of the gateway to be able to record all electronic customer products entering or leaving the warehouse gate.


2. Passive RFID tags with UHF frequency to be struck on all the carton boxes before they store in the ABC’s warehouse.


3. A host computer system with the application software to be able to understand, translate and manipulate the frequency data from read by the readers.


4. A network relating the various host computers to a server for a centralized storage of data about the stock.

sample picture
: RFID Antennas and c0mputer set
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Ken Ngan’s Estimate Budget

• Estimate of resources and cost System / Human Resource Quantity Cost per unit Total RFID Reader 2 x HK$15,000 (Sub Total HK$30,000)
  
• Antenna (Circular Polarization) 4 x HK$2,000 (Sub Total HK$8,000)


• Signaling Cable to connect reader and antennas 80M (20M for each antenna) HK$5.6 (Sub Total HK$448)


• RFID Developer Kit for system installation (CD, brackets, transformer, LAN cable, BNC plus) 1 pack x HK$1,350 (Sub Total HK$1,350)


• UHF tags (Orientation-Insensitive) 5,000 tags x HK$3 (Sub Total HK$15,000)


• Application Software to host computer system 1 x HK$3,000 (Sub Total HK$3,000)


• Hardware Technician 1 HK$700 per day x 5 working days (Sub Total HK$3,500)


• IT / Software Engineer for new RFID system networking 1 HK$1,150 per day HK$3,450 (Sub total 3 working days)


• Trainers for RFID training course 2 x HK$4,000(Sub total HK$8,000)
  

Total: HK$72,748

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Selection of RFID Tag

The orientation-insensitive RFID tag is selected for ABC Ltd as RFID accessories; the reasons are that orientation insensitive design allows for reading at any angle (no dead spots), this type of RFID tag can increase system level read rate success, and increase overall system reliability.

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With an optimal solution to this warehouse improvement project, I prefer adopting the orientation-insensitive RFID tag to using the orientation-sensitive RFID tag.

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Position and Orientation of the tags

If a UHF tag were placed at the ideal side face location, a carton on the outside of a pallet would undoubtedly read well, but a carton positioned just behind it would fail to read at all. So to optimize the chances of reading stacked cartons on a pallet, a location must be identified that allows for some transmission of the RF-energy.

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To match the ABC Ltd’s packing style (four layers of carton boxes, and one layer with four carton boxes, 16 carton boxes in a pallet), I recommend to put tag on the side face of each carton in column 1 and 2, likewise on the another outside face in column 3 and 4.

End

Best Regards,