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萬芳醫院建構 Sensor Network 的規劃
短中長期目標規劃
短期目標
•行動化及完整化醫療資訊系統 •應用 RFID 提高病人安全•應用無線網路加速醫療資料的傳遞•應用行動裝置提升醫院機動性
中期目標
•整合跨功能的系統及作業流程•規劃智慧型無線照護環境 •規劃系統平台之通訊與資料格式標準•規劃行動醫療照護環境
長期目標
•建立智慧型行動醫療照護環境•將系統應用擴展至居家照護甚至隨身照護
使用者登入
醫生帳號密碼輸入
護士帳號密碼輸入
首頁 - 病患名單
病人基本資料
高風險值報告 檢驗報告 放射報告
血液報告
鏡檢報告
生化報告
血清免疫報告
用藥
線上藥典
RFID tag
個人使用紀錄
萬芳醫院建構 Sensor Network 的規劃
短期目標規劃
應用無線技術於生理檢驗模組範例( 短期目標 )
1. 量測生理資料 2. 記錄生理資料於紙本上 3. 至護理站輸入生理資料
* 書寫錯誤 * 輸入錯誤
2. 確認生理資料1. 量測生理資料
預估作業所需時間 : 10 min
預估作業所需時間 : 1 min
應用地點 : 院內
應用地點 : 院內、居家、救護車
整合性的跨功能系統設計範例 流程 : 開藥 ( 醫生 ) 包藥 ( 藥劑師 ) 給藥 ( 護士 )
1.醫生開立醫囑
write
3.護理查詢用藥
Read
2.藥局包藥
Read/write
4.護理給藥並記錄
write
藥局送藥
1. 醫生開立醫囑2. 系統依用藥頻率及用藥期間展開用藥明細檔3. 藥局根據包藥及送藥4. 護士查詢安排照護行程5. 護士根據時給藥及記錄
* 應用 RFID 提高病人用藥安全
病人病歷 + 用藥明細 為具生醫研究價值之資料庫
* RFID
* RFID
The System Architecture
Physician requests information using a PDA.The request is transmitted to Web Server
Patient Safety Portal/Web Service Server
The Patient Web Portal sends a request/response message to retrieve the “Patient Safety Data”
Lab Med Ris HRR BasicData
XML
Patient Safety Data is transmitted to requestor and formatted to “XML”
Patient Safety Portal sends a request/responseto retrieve “HIS” data
IDS
System Deployment in the Ward Area
Admission, Registry & Identity Verification
Room 1
Room N
Discharge
Hospital Information Center
Web Service ServerClinical Decision Engine
Identity Verification (With Bedside Card)
Dept. Of Radiology Injection Room
Identity Verification(with Medical Order, Application Form and HR
Endoscopy Room
Complains from personnel • Wi-Fi remote transmission delay Data pre-load might run out of the limited memory
of handheld Data loaded by reading RFID pasted to different
regions might not work when emergent condition Data pre-load by the indoor positioning is one way
to go (Context-awareness) • Handheld device management When? Who? Where? Which?
Some Problems in the Ward Area
ClinicalDecisionEngine
RFID Mobile Assistance
RFID Control
Front-end MedicalAssistance
Wi-Fi SignalCollector
Web Services Platform
Patient
Report
Medication
Location-aware
MedicalDataBase
RadioMap&FeatureDataBase
RFID
Handheld RFID Medical Assistant System with Location-based Service
Wi-Fi
HRR
Local Data Collector
Position Engine
Location-aware Data Access and Location-aware Mobile Database
Personnel Handheld Location-aware Service
Radio Map and Feature Database
Collect WiFi Signal Samples
Position Engine
send(Samples) Analyze
Samplesrequest(Sample Feature)
Search and Match
response(Candidates)Rank
request(Local Data)
send(Samples)
Local Data Collector
Medical Database
return(Position)Position Change?
send(New Position) request(New Position)
response(New Local Data)return(New Local Data)
Package Up Local Data
update(Packaged Local Data)
show(Local Data)
Real-time Status Management for Mobile Devices
Personnel Handheld Location-aware Service
Radio Map and Feature Database
Collect WiFi Signal Samples
Position Engine
send(Samples)
Analyze Samples
request(Signal Feature)
Search and Match
response(Candidates)Rank Candidates
update(Device Status)
Check Device Status
RequestDevice Status
send(Samples)
request()
response(Device Status)
return(Device Status)Show Device
Status
Phase 2 : Feature ExtractingPhase 3 : Position Algo. DesigningPhase 4 : On-line Positioning
PositionAlgorithm
802.11 Base Indoor Position System
RadioMap
DataBase
RadioMap
DataBase
Signals for Radio Map
Estimated Location
AP FeatureDataBase
FeatureDataBase
RadioMap
DataBase
RadioMap
DataBase
Query and Response
Signal for Positioning
Phase 1 : Radio Map Calibration
Received Signal Strength Indicator (RSSI) and MAC address would be recorded
Ref. point density and sampling time should be decided first by system requirements
Meter-level position systems usually have square-meter-level ref. point density
Divides the radio map into individual regions by layout
802.11 Base Indoor Position System
Phase 1 : Radio Map Calibration (1/2)
RSSI2 MAC2 RSSI1 MAC1
AP2
AP1
Ref. Point
802.11 Base Indoor Position System
Phase 1 : Directional Effect (2/2)
D
U
EW
S
N
0
2
4
6
8
10
12
14
16
18
20
下 上 北 西 東 南
方向
基地台數量
基地台數量
-60
-50
-40
-30
-20
-10
0下 上 北 西 東 南
方向
(dbm)訊號強度
(dbm)訊號強度
802.11 Base Indoor Position System
Phase 2 : Feature 1 - Received APs (1/2)
U
W
S
N
D
EMAC1,MAC2,…MACw
MAC1,MAC2,…MACu
MAC1,MAC2,…MACs
w
u
s
Num. of APs List of APs
AP Matching Table
802.11 Base Indoor Position System
Phase 2 : Feature 2 – Distribution (2/2)
It’s difficult to evaluate what kind of the bell-shaped distribution is
We can characterize the RSSI of an AP by sample mean μ and stand deviation σ
U
W
S
N
D
E
MAC1 μ 1 σ 1
MAC2 μ 2 σ 2
MAC3 μ 3 σ 3
MAC4 μ 4 σ 4
Phase 3 : Position Algorithm - AP Matching (1/6)
802.11 Base Indoor Position System
AP1AP2
AP3AP4
Candidate Set S :Members in S can receive {AP1, AP2, AP3} in the radio map
Given A = {AP1, AP2, AP3}, use A to find the solution point set S
AP5shift
Filter out the newly adding AP by building a AP table to prevent empty S Ignore the rushing AP which is collected on positioning with detecting probabilities lower than a threshold
802.11 Base Indoor Position System
Phase 3 : Position Algorithm - AP filter (2/6)
In order to choose one of the candidate member in S from step one, we need to give each of them a score
Choose the point with best-matched score as the result
To score the member of S instead of all ref. points in the radio map
Find the way to measure the error of strength of each candidate member
802.11 Base Indoor Position System
Phase 3 : Position Algorithm – Scoring (3/6)
Avgk : Avg. power of APk on positioning μk : Avg. power of APk in the radio map R : total number of detected APs Si : (Region, Ref. ID, Direction), member of S
IIdeal 1 :
Ignore standard deviation Larger variance means that the sample value shifts
significantly One way to compare two random variables is to
standardize them
802.11 Base Indoor Position System
Phase 3 : Scoring Methods – Scoring (4/6)
R
kkki AvgSError
1
)(
σk : the s.t.d. of signal strength of APk in the radio map
Ideal 2 :
How do we value each AP? - Amplify the error(>1) of avg. power of each AP - Lessen the error(>1) of avg. power of each AP
Ideal 3 :
802.11 Base Indoor Position System
R
k k
kkkki
AvgAvgSError
1
)(
R
k k
kki
AvgSError
1
)(
Phase 3 : Scoring Methods – Scoring (5/6)
Similarly, How do we value the candidate member, Si ?
A : set of detected APs on positioning
ASi : set of collected APs on Si in the radio map
A is contained in ASi by the definition of Si
AP matching degree :
Final Scoring Formula :
iSA
A
802.11 Base Indoor Position System
iS
i
AA
SWeight1
)(
R
k k
kkkk
S
ii
AvgAvg
AA
SErrorSScore
i
1
1)()(
Phase 3 : Scoring Methods – Scoring (6/6)
802.11 Base Indoor Position System
Position System Block Diagram
AP Filter
AP Matching
Scoring
Estimating
Method 1 Method 2 Method n
Candidate Set S
Result
Power Signatures of {AP1,…APR}
Connection
Web Service Position Platform
FeatureDataBase
FeatureDataBase
Radio MapDataBase
Radio MapDataBase
Experiments and Evaluations
• 實驗地點– 台大資訊系五樓東側 – 在既有的無線基地台
中,選擇其中三個測試
Parameters and Scoring Functions
• 1 reference point / 9 m2
• 100 samples per direction in each reference point in constructing the radio map
• 4 scoring functions in the experiments
位置誤差的實驗 (1/2)
誤差累積分佈
00.10.20.30.40.50.60.70.80.91
0 1 2 3 4 5 6 7 8 9 10 11 12 13
( )誤差 公尺
(1)公式(2)公式(3)公式(4)公式
位置誤差的實驗 (2/2)
• 定位誤差(單位:公尺)• 3 公尺內可達 90% 可信度, 6 公尺內可達 95% 的可信度• 在同樣的條件與環境下, Ekahau 系統的定位平均誤差為 2.67
公尺
Method Average Max Standarddeviation
1 3.91 12.37 2.92
2 3.45 12.37 2.86
3 2.79 12.37 2.47
4 2.07 6 1.75
Method Error 3m≦ Error 6m≦
1 59% 73%
2 67% 80%
3 75% 88%
4 92% 95%
區域辨識率的實驗
Method Region Point Direction
1 0.71 0.19 0.02
2 0.76 0.24 0.02
3 0.8 0.31 0.06
4 0.87 0.37 0.05
位置感知服務的效能提升
Method Avg. Time
Location-aware 0.81
Traditional 2.23
結論與討論
“ Valley of Death”
Research & Invention
Innovation: new businessViableViable
BusinessBusiness
The Darwinian SeaBasic Basic
ResearchResearch
InventionInvention Innovation&
New Business
市場考驗市場考驗
創新創業價值鏈斷層創新創業價值鏈斷層• 有沒有更簡單有效的室內定位方法?
– 學界:藉由研發更好的設備,更好的演算法,更好的 Scoring Function 等策略,來改善室內定位效能
• 各位同學可以繼續研究– 業界:利用既有成熟的技術,改善作業流程與程序,來改善室內定位效能
• 僅利用 Passive RFID 就可以達到非常接近 100% 區域定位能力的方法• 研發太空船上的原子筆
– 用鉛筆
Q & A & D
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