Digitally-Bypassed Transducers: Interfacing Digital Mockups to Real-Time Medical Equipment

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Digitally-Bypassed Transducers Interfacing
Digital Mockups to Real-Time Medical Equipment

• Scott Sirowy, Tony Givargis and Frank Vahid

Department of Computer Science and
Engineering University of California,
Riverside ssirowy,vahid_at_cs.ucr.edu
Center for Embedded Computer Systems University
of California, Irvine givargis_at_ics.uci.edu

• This work was supported in part by the National
  Science Foundation

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Introduction Medical Device SW Development
Ventilator

• PC Simulation
• Simulate medical device and physiological system
  completely in software
• Supports rapid software changes, faster than
  real-time execution, and avoids potential safety
  concerns

Matlab, MML, VisSim, etc
Lung
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Introduction Medical Device SW Development

• Physical Mockups
• Later in development, migrate simulated
  physiological models to physical models
• Used when medical device software is running on
  actual hardware
• Potential inability to adapt to new features

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Introduction Medical Device SW Development
Physical Mockups
PC Simulation
(Flexibility, speed, no real hardware)
(Real Hardware, more realistic, costly, some
scenarios difficult to model )

• Digital Mockups
• Combines the benefits of faster than real-time
  execution of simulation with advantages of
  developing software on real device
• Potentially cheaper than physical mockups too

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Introduction Medical Device SW Development

• PC Simulation
• Supports rapid software changes, faster than
  real-time execution, and avoids potential safety
  concerns
• Physical Mockups
• Used when medical device software is running on
  actual hardware
• Potential inability to adapt to new features
• Digital Mockups
• Combines the benefits of faster than real-time
  execution of simulation with advantages of
  developing software on real device
• Potentially cheaper than physical mockups too

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Introduction Medical Device SW
DevelopmentPhysical Mockups
Physical Tube
SW Core
Pressure and Volume Sensors
Transducers
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Introduction Medical Device SW
DevelopmentDigital Mockups
Left Unconnected
Digital Lungs Mockup
SW Core
Digital Interface
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Digital MockupsDigitally-Bypassed Transducers
Digitally-bypassed Transducer
Medical Device
Digital Mockup
Input 1
Output 1
(Digital)
Sensed Input

Input n
Output n
(Digital)
Sensed Input
SW Core
Physical Value
Input 1
Output 1
(Digital)

Physical Value
Input n
Output n
(Digital)
Control/Synchronization Channel
Digital Bypass
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Digital MockupsDigitally-Bypassed Transducers
Output Digitally-Bypassed Transducer
Input Digitally-Bypassed Transducer
Bypass Transducer
Digital output
(from medical device)
Digital input
(to medical device)
Digital input
Sensed Value
Digital output
Physical Value
Transducer
Transducer

• Simple and inexpensive hardware additions enable
  bypassing the transducer inputs and outputs, and
  enable working completely in the digital domain

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Digital MockupsMedical Device-Digital Mockup
Synchronization

• Rate Synchronization Dedicated
  Control/Synchronization Channel used to exchange
  connectivity information, sampling rates, and
  mockup execution speeds

All communication done on the bi-directional
control/synchronization channel
Step 1 On initial connection, digital
connectivity handshake
Digital Mockup
Medical Device
Step 1
Step 2 Medical device sends required sampling
rate
Step 2
Step 3 Medical device and Digital Mockup agree
on execution speed (real time, 2X faster, etc)
Step 3
Step 4
Step 4 Begin Execution
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Medical Software Development with
Digitally-Bypassed Transducers

• All Digitally-Bypassed
• Transducers

Physical Interface
Tube
2) Combined Digital and Transducers

• Full Interaction with
• Physical System

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Digitally-Bypassed TransducersEarly Prototype
Medical Device (Pacemaker)
Control/Synchronization Channel
Open leads for real physical analog connections
Digital Mockup of a Heart
Transducers
Digital Inputs/Outputs
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Medical Software DevelopmentPrototype Results

• Heart Digital Mockup and Pacemaker
• Implemented both pacemaker model and digital
  model using a number of off-the-shelf
  microcontrollers
• Digital Mockup based off a simple physical heart
  model
• Able to test pacemaker in real-time, and faster
  and slower than real time

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Medical Software DevelopmentPrototype Results

• Lung Digital Mockup and Ventilator
• Lung Mockup Ventilator based off of models from
  the NSR Physiome Projects
• Plan on augmenting a real ventilator with
  digitally-bypassed transducers in the near future

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Conclusions

• With a small amount of hardware and software
  additions, we introduced the digitally-bypassed
  transducer
• Digitally-bypassed transducers enable interfacing
  to digital mockups, enable medical software
  development at faster than real-time execution
  while still developing software on the real
  medical device