Package: ros

Pause code execution to achieve desired execution rate



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.


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Create a rate object that runs at 1 Hz.

r = robotics.Rate(1);

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

for i = 1:10
	time = r.TotalElapsedTime;
	fprintf('Iteration: %d - Time Elapsed: %f\n',i,time)
Iteration: 1 - Time Elapsed: 0.004142
Iteration: 2 - Time Elapsed: 1.000765
Iteration: 3 - Time Elapsed: 2.001280
Iteration: 4 - Time Elapsed: 3.000867
Iteration: 5 - Time Elapsed: 4.001346
Iteration: 6 - Time Elapsed: 5.001546
Iteration: 7 - Time Elapsed: 6.000839
Iteration: 8 - Time Elapsed: 7.000975
Iteration: 9 - Time Elapsed: 8.000789
Iteration: 10 - Time Elapsed: 9.001011

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 rateControl 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.

See Also

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Introduced in R2019b