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: 0.003397
Iteration: 2 - Time Elapsed: 1.011038
Iteration: 3 - Time Elapsed: 2.003495
Iteration: 4 - Time Elapsed: 3.003328
Iteration: 5 - Time Elapsed: 4.003826
Iteration: 6 - Time Elapsed: 5.003539
Iteration: 7 - Time Elapsed: 6.002839
Iteration: 8 - Time Elapsed: 7.002530
Iteration: 9 - Time Elapsed: 8.002499
Iteration: 10 - Time Elapsed: 9.002562

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