DigitallyBypassed Transducers Interfacing Digital Mockups to RealTime Medical

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

Introduction: Medical Device SW Development n PC Simulation n n Simulate medical device and physiological system completely in software Supports rapid software changes, faster than real-time execution, and avoids potential safety concerns Ventilator Matlab, MML, Vis. Sim, etc Lung

Introduction: Medical Device SW Development n Physical Mockups n n n 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

Introduction: Medical Device SW Development Ventilator Matlab, MML, Vis. Sim, etc Lung Physical Mockups PC Simulation (Flexibility, speed, no real hardware) n (Real Hardware, more realistic, costly, some scenarios difficult to model ) Digital Mockups n n 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

Introduction: Medical Device SW Development n PC Simulation n n Physical Mockups n n n Supports rapid software changes, faster than real-time execution, and avoids potential safety concerns Used when medical device software is running on actual hardware Potential inability to adapt to new features Digital Mockups n n 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

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

Introduction: Medical Device SW Development Digital Mockups Left Unconnected Ventilator Digital Lungs Mockup SW Core Digital Interface

Digital Mockups Digitally-Bypassed Transducers Medical Device Input 1 Sensed Input Output 1 (Digital) … Input n SW Core Sensed Input Output n (Digital) Physical Value Input 1 Output 1 (Digital) Physical Value … Input n Output n (Digital) Control/Synchronization Channel Digital Bypass = Digitally-bypassed Transducer Digital Mockup

Digital Mockups Digitally-Bypassed Transducers Input Digitally-Bypassed Transducer Output Digitally-Bypassed Transducer Bypass Transducer Digital input (to medical device) Digital output n Digital output (from medical device) Digital input Transducer Sensed Value Transducer Simple and inexpensive hardware additions enable bypassing the transducer inputs and outputs, and enable working completely in the digital domain Physical Value

Digital Mockups Medical Device-Digital Mockup Synchronization n 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 Step 2: Medical device sends required sampling rate Step 3: Medical device and Digital Mockup agree on execution speed (real time, 2 X faster, etc) Medical Device Step 1 Step 2 Step 3 Step 4: Begin Execution Digital Mockup

Medical Software Development with Digitally-Bypassed Transducers Digital Lungs Mockup Ventilator SW Core 1) 2) All Digitally-Bypassed Transducers Physical Interface Ventilator SW Core Tube Digital Lungs Mockup 2) Combined Digital and Transducers Ventilator SW Core 3) 4) Full Interaction with Physical System

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

Medical Software Development Prototype Results n Heart Digital Mockup and Pacemaker n n n Implemented both pacemaker model and digital model using a number of off-theshelf microcontrollers Digital Mockup based off a simple physical heart model Able to test pacemaker in real-time, and faster and slower than real time

Medical Software Development Prototype Results n Lung Digital Mockup and Ventilator n n 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

Conclusions n With a small amount of hardware and software additions, we introduced the digitally-bypassed transducer n 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