CHREC F3: Target Tracking Rafael Garcia 11/26/08

2 F3 Goals, Motivations, & Challenges Goals  Develop applications & design strategies for scalable architectures from case-study  Analyze & examine available multi-FPGA platforms and tools for scalable system design Motivations  Meet performance requirements in HPC/HPEC scenarios by mapping across multiple FPGAs  Exploit multi-FPGA platforms to develop larger, complex designs and algorithms  Increase understanding of performance prediction, power, and usability for scalable apps Challenges  Perform multilevel algorithm partitioning, analysis, and optimization for multi-FPGA systems  Determine influence of application characteristics on selection of platforms, tools and languages F3 Insights Formulation Translation Design Execution

Kalman Filter Overview Traditional Kalman filters estimate the state of a dynamic system in a noisy environment Commonly used in target prediction and can be extended to multiple dimensions, targets, and models Excellent target tracker when an accurate model is known  Useful even if an accurate model is not known

Current Architecture 4 tightly coupled FPGAs mapped to 4 quadrants  System is driven by two global clocks  100MHZ inter-FPGA communication links  50MHz data-processing clock 2-step processing cycle returns results at 25MSa/s  Inter-FPGA communication occurs when target crosses a quadrant boundary Current state of target is passed along Non-pipelined design  2-step cycle where one cycle depends on the previous one and the other cycle depends on pseudo-sensor data from host CPU Low frequency and lack of pipeline registers is expected to lower power consumption 2-cycle design simplifies communication network

Current Architecture Continuously receiving pseudo-sensor data and returning condensed information Limited to a single target per quadrant Set sensor sampling rate of 25MSa/s ResourceM4K ramsDSPsALUTs Stratix II: EP2S180F1020C3 1%15%2%

Simplified Algorithm Assumes steady-state operation  Target must closely follow given movement model for accurate results Allows for precomputed covariance and Kalman-gain terms Model tracks four parameters  Horizontal position  Vertical position  Horizontal velocity  Vertical velocity Algorithm Changes  Remove the hardcoded terms, increasing prediction accuracy during non- steady-state situations  Modify model to include Z- axis parameters for airborne targets SensorTargetPrecisionResourceKernel Low PowerSlowFixedLowKalman Filter Fast SamplingFastFixedLowKalman Filter Multi-ScaleAirborneFloatingHighMKS High-NoiseNoisyFloatingMediumKalman Filter SelectiveMultipleFloatingHighFeature Selection New Module Types RCML Representation

7 VA migration

Kalman Filter Estimates state of a dynamic system in a noisy environment  In this case, the ‘dynamic system’ is a moving target Commonly used in target prediction and can be extended to multiple dimensions, targets, and models Assumes sensor noise is white Gaussian noise Requires a pre-programmed model describing the target’s motion Works in a continuous 2-cycle loop Developed in 1960 by Rudolf E. Kalman (A UF professor from !)

Kalman Filter can be viewed as a simple black box  An input stream of samples measuring a target’s position is contaminated with noisy samples  The output is a stream of samples with most of the noisy samples filtered Kalman System Models Accurate Samples Noisy Samples Mostly Accurate Samples Kalman Filter -9.8 m/sNE wind at 23mph Follows Road

Reasons for sensor noise Battery Power  variable battery voltage voltage regulators cost money, draw power, and are not perfect Sensors  low quality sensors cost-cutting for mass production sometimes requires cheap sensors  incorrectly deployed sensors bad orientation, obstructed sensor Environment  environmental conditions rain, dust, night-time tracking, snow Multiple targets  misinterpreted samples from neighboring targets during multiple-target tracking Sensor processing stage must ensure proper target isolation Wireless signal  bad data from neighboring sensors due to a weak wireless signal

Kalman Filter example

PR Virtual Architecture with Kalman Filters Sensor records samples Image processing step extracts specific features  Target size, vertical position, horizontal position, target bearing, elevation, etc. Kalman filters extract sensor noise Results are sent to a central location to be displayed Module interface Kalman filter Kalman filter Kalman filter Kalman filter Kalman filter Switch 1 Switch 2 Switch 3Switch 4 Switch 5 Sensor Interface Display Interface Communication architecture VLX25

FPGA and PR benefits for the Kalman Filter FPGA amenable features  Low memory requirements Simple filter with streaming inputs and outputs  Can be implemented using only logic and MAC units  Requires only multiplication and addition No complex time-consuming operations such as division, square-root, differentiation, etc.  Low bandwidth requirements Filter receives/produces a stream of coordinates, not a stream of images PR amenable features  Optimum resource usage The right filter type for the right job  Swapping modules does not halt execution Active filters are never disturbed

Experimental FPGA Power Measurements

GiDEL Host Specifications  Dual Xeon 3.00 GHz processors (Pentium 4 era)  2GB RAM  Single 500GB hard drive  CD Drive  600W max power supply  (Kappa clone) ProcStar II Power Characteristics  Main board supply rated at 7.6A at 3.3V 7.6A × 3.3V = 25.08W maximum power available to:  Stratix II EP2S180 FPGA (4x)  2GB SODIMM DDR memory(2x)(only 1 used for tests)  64MB SRAM memory (8x)  Miscellaneous oscillators, peripherals, controllers, etc. This means roughly 5W max available to each FPGA Test Design Characteristics  Kalman tracking filters Heavy multiplier usage, no block rams, minimal logic usage (w/ dedicated multipliers)  In all cases, design runs at 33MHz Experimental Setup

Methodology GiDEL host system measured without FPGA board  P3 Kill-A-Watt AC power meter used for measurements 0.2% documented accuracy  Accurate to within 1 Watt  7 different test cases with varying power utilization GiDEL host system measured with FPGA board  Same 7 test cases were used (without loading an FPGA design) This provides minimum power-use baseline for ProcStar II  GiDEL board is loaded with FPGA-computationally intensive design CPU is kept idle Power consumption under regular design is measured 33 MHz)  2% logic use (per FPGA)  15% multiplier use (per FPGA)  1 filter instance per FPGA Power consumption under maximum-multiplier-use design is measured 33 MHz)  4% logic use  88% multiplier use  7 filter instances per FPGA Power consumption under maximum-logic-use design is measured 33 MHz)  77% logic use  0% multiplier use  34 filter instances per FPGA

Test CasesWithout ProcStar II With ProcStar II 1. Server off (not standby) 8 W 2. Idle127 W137 W 3. Idle with CDROM spinning 131 W141 W 4. Full HDD load (defrag) 132 W143 W 5. Full CPU load (1 thread) 188 W198 W 6. Full CPU load (4 threads) 255 W257 W 7. Full CPU/HDD load (3 threads, defrag) 258 W264 W Results: Baseline ProcStar II Threads are simple while(1) loops Although only 2 cores are present, 4 threads were used to bypass Hyper-threading and OS scheduling  HDD load is an exception since defrag requires its own thread to be effective

Results: Kalman Filters on ProcStar II Power estimates  12.5% toggle rate 33 MHz  Experimental numbers below assume FPGAs consume all power (ie. ProcStar II memories, glue logic, etc. consume 0W) Design 1  140 W total power ~3.25 W per FPGA  15% mult., 2% logic  1 filter instance, high F max Design 2  140 W total power ~3.25 W per FPGA  88% mult., 4% logic  7 filter instances, high F max Design 3  152 W total power ~6.25 W per FPGA  0% mult., 77% logic  34 filter instances, low F max

Results: Kalman Filter in ProcStar II *Measured power is derived by subtracting baseline power consumption on ProcStar II board from measured power consumption and dividing by 4  Power consumed from board components not accounted for, actual FPGA power consumption is lower

Questions?