Dynamically reconfigurable systolic array accelerators: a case study with extended Kalman filter and discrete wavelet transform algorithms

Field programmable gate arrays (FPGAs) are increasingly being adopted as the primary on-board computing system for autonomous deep space vehicles. There is a need to support several complex applications for navigation and image processing in a rapidly responsive on-board FPGA-based computer. Developing such a computer requires the designer to explore and combine several design concepts such as systolic array (SA) design, hardware-software partitioning and partial dynamic reconfiguration (PDR). In this study a microprocessor/co-processor design that can simultaneously accelerate multiple single precision floating-point algorithms is proposed. Two such algorithms are extended Kalman filter (EKF) and discrete wavelet transform (DWT). Key contributions include (i) polymorphic systolic array (PolySA), comprising partial reconfigurable regions that can accelerate algorithms amenable to being mapped onto linear SAs and (ii) performance model to predict the overall execution time of EKF algorithm on the proposed PolySA architecture. When implemented on a low-end Xilinx Virtex4 SX35 FPGA, the design provides a speed-up of at least 4.18x and 6.61x over a state-of-the-art microprocessor used in spacecraft systems for the EKF and DWT algorithms, respectively. The performance of EKF algorithm on the proposed PolySA architecture was compared against the performance on two types of conventional (non-polymorphic) hardware architectures and the results showed that the proposed architecture outperformed the other two architectures in most of the test cases.