TRUETIME: Real-time Control System Simulation with MATLAB/Simulink

TRUETIME: Real-time Control System Simulation with MATLAB/Simulink,Dan Henriksson,Anton Cervin,Karl-Erik Årzén

TRUETIME: Real-time Control System Simulation with MATLAB/Simulink   (Citations: 17)
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Traditional control design using MATLAB/Simulink, often disregards the temporal effects arising from the actual implementation of the controllers. Nowadays, controllers are often implemented as tasks in a real-time kernel and communicate with other nodes over a network. Consequently, the constraints of the target system, e.g., limited CPU speed and network bandwidth, must be taken into account at design time. For this purpose we have developed TRUETIME, a toolbox for simulation of distributed real-time control systems. TRUETIME makes it possible to simulate the timely behavior of real-time kernels executing controller tasks. T RUETIME also makes it possible to simulate simple models of network protocols and their influence on networked control loops. TRUETIME consists of a kernel block and a network block, both variable-step S-functions written in C++. T RUETIME also provides a collection of MATLAB functions used to, e.g., do A/D and D/A conversion, send and receive network messages, set up timers, and change task attributes. The T RUETIME blocks are connected with ordinary continuous Simulink blocks to form a real-time control system. The TRUETIME kernel block simulates a computer with an event-driven real-time kernel, A/D and D/A converters, a network interface, and external interrupt channels. The kernel executes user-defi ned tasks and interrupt handlers, representing, e.g., I/O t asks, control algorithms, and communication tasks. Execution is defined by user-written c ode functions (C++ functions or m-files) or graphically usin g ordinary discrete Simulink blocks. The simulated execution time of the code may be modeled as constant, random or even data-dependent. Furthermore, the real-time scheduling policy of the kernel is arbitrary and d ecided by the user. The TRUETIME network block is event driven and distributes messages between computer nodes according to a chosen network model. Currently five of the most common medium access control proto cols are supported (CSMA/CD (Ethernet), CSMA/CA (CAN), token-ring, FDMA, and TDMA). It is also possible to specify network parameters such as transmission rate, pre- and post-processing d elays, frame overhead, and loss probability. TRUETIME is currently used as an experimental platform for research on flexible approaches to real-time implementation and sched uling of controller tasks. One example is feedback scheduling where feedback is used in the real-time system to dynamically distribute resources according to the current situation in the system.
Published in 2007.
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