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: 0.015165
Iteration: 2 - Time Elapsed: 1.011196
Iteration: 3 - Time Elapsed: 2.004998
Iteration: 4 - Time Elapsed: 3.005954
Iteration: 5 - Time Elapsed: 4.005940
Iteration: 6 - Time Elapsed: 5.012045
Iteration: 7 - Time Elapsed: 6.002761
Iteration: 8 - Time Elapsed: 7.002669
Iteration: 9 - Time Elapsed: 8.002443
Iteration: 10 - Time Elapsed: 9.002448

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