1. 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}@cs.ucr.edu ‡Center for Embedded Computer Systems University of California, Irvine givargis@ics.uci.edu This work was supported in part by the National Science Foundation

2. 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

3. 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

4. Ventilator Matlab, MML, VisSim, etc Lung 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

5. 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

6. Ventilator Physical Lungs Mockup Introduction:Medical Device SW DevelopmentPhysical Mockups Physical Tube SW Core Pressure and Volume Sensors Transducers

7. Ventilator Introduction:Medical Device SW DevelopmentDigital Mockups Left Unconnected Digital Lungs Mockup SW Core Digital Interface

8. 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

9. 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

10. 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

11. Digital Lungs Mockup Digital Lungs Mockup SW Core SW Core SW Core Ventilator Ventilator Ventilator Medical Software Development with Digitally-Bypassed Transducers • All Digitally-Bypassed • Transducers Physical Interface Tube 2) Combined Digital and Transducers • Full Interaction with • Physical System

12. 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

13. 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

14. 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

15. 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