waitfor

Package: ros

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 = 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.

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: 0.003034
Iteration: 2 - Time Elapsed: 1.015130
Iteration: 3 - Time Elapsed: 2.003068
Iteration: 4 - Time Elapsed: 3.004029
Iteration: 5 - Time Elapsed: 4.003588
Iteration: 6 - Time Elapsed: 5.003816
Iteration: 7 - Time Elapsed: 6.002938
Iteration: 8 - Time Elapsed: 7.002779
Iteration: 9 - Time Elapsed: 8.002772
Iteration: 10 - Time Elapsed: 9.002782

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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Topics

Introduced in R2019b