Tackling feedback design complexity

Abstract

Feedback control dealt with the application of cheap commercial off-the-shelf (COTS) hardware to control problems. What does not come cheap, however, is the design, in terms of software and people skills. Engineering design was mostly based on hand calculations 30 years ago, and scientific calculators from the likes of Hewlett Packard and Texas Instruments were all the rage with designers. The feedback loop was expressed as an equation G = A/(1-AB), which still forms the basis of most simulation and design software today, where G is the gain of the system, with A representing the feed-forward element, typically an amplifier, and B representing the feedback element. The minus sign indicates negative feedback. The input to the equation is typically by means of a matrix, which is the foundation of several of today's leading software packages, including, amongst others, Math Works Matlab (matrix laboratory) and Simulink, and National Instruments (NI) MatrixX and Lab View. Both companies are working relentlessly to complete the design cycle from design and simulation through to testing and commissioning in hardware, and even in silicon. The Math Works has recently launched Embedded Matlab, which allows users to generate embeddable C code directly from Matlab programs, avoiding the common, time-consuming and error-prone process of rewriting Matlab algorithms in C. Embedded Matlab supports many high-level Matlab language features, such as multidimensional arrays, real and complex numbers, structures, flow control and subscripting. The conversion to C code is performed by Real-Time Workshop 7. If Simulink is used, synthesisable Verilog and VHDL can also be generated.