waitfor

Package: robotics

Pause code execution to achieve desired execution rate

Description

example

waitfor(rate) pauses execution until the code reaches the desired execution rate. The function accounts for the time that is spent executing code between waitfor calls.

numMisses = waitfor(rate) returns the number of iterations missed while executing code between calls.

Examples

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Create a rate object that runs at 1 Hz.

r = rateControl(1);

Start a loop using the rateControl object inside to control the loop execution. Reset the object prior to the loop execution to reset timer. Print the iteration and time elapsed.

reset(r)
for i = 1:10
	time = r.TotalElapsedTime;
	fprintf('Iteration: %d - Time Elapsed: %f\n',i,time)
	waitfor(r);
end
Iteration: 1 - Time Elapsed: 0.006483
Iteration: 2 - Time Elapsed: 1.013151
Iteration: 3 - Time Elapsed: 2.007437
Iteration: 4 - Time Elapsed: 3.006478
Iteration: 5 - Time Elapsed: 4.007640
Iteration: 6 - Time Elapsed: 5.013228
Iteration: 7 - Time Elapsed: 6.004669
Iteration: 8 - Time Elapsed: 7.003984
Iteration: 9 - Time Elapsed: 8.003659
Iteration: 10 - Time Elapsed: 9.004903

Each iteration executes at a 1-second interval.

Input Arguments

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Rate object, specified as a handle. This object contains the information for the desired rate and other information about the execution. See robotics.Rate for more information.

Output Arguments

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Number of missed task executions, returned as a scalar. waitfor returns the number of times the task was missed in the Rate object based on the LastPeriod time. For example, if the desired rate is 1 Hz and the last period was 3.2 seconds, numMisses returns 3.

Introduced in R2016a