How can I detect a sign change without detection of 0 holding (Simulink)

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Nick 2016-4-14

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评论： Nick 2016-4-18

Hi,

I want to detect sign changes with Simulink blocks. By using the common libary, I also detect when the signal jumps from positive to 0, hold 0 and rises back to the positive area, which is not beneficial in my case. Do you know a way how to detect sign changes with real zero passings?

Thanks.

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Answer 1

Anish Mitra 2016-4-18

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You can make use of the "Detect" blocks in the Simulink>Logic and Bit Operations library.

>> web(fullfile(docroot, 'simulink/slref/detectfallnegative.html'))

These blocks are for Fixed Step solvers. If the logic needs to be implemented using Variable Step solvers, then you can use a Memory block to construct the logic. Essentially this would mean taking the product of the signal, and the signal delayed by 1 (using a Memory block, not a delay). If the sign of the product is negative, it means that there is a zero crossing at that particular time step.

Hope this helps.

Anish