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added a fixed control period to loop (backport #647) #650

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Merged
destogl merged 1 commit into from
Feb 17, 2022
Merged

added a fixed control period to loop (backport #647) #650

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23 changes: 13 additions & 10 deletions controller_manager/src/ros2_control_node.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -40,22 +40,25 @@ int main(int argc, char ** argv)
std::thread cm_thread([cm]() {
RCLCPP_INFO(cm->get_logger(), "update rate is %d Hz", cm->get_update_rate());

rclcpp::Time begin = cm->now();
rclcpp::Time current_time = cm->now();
rclcpp::Time previous_time = current_time;
rclcpp::Time end_period = current_time;

// Use nanoseconds to avoid chrono's rounding
std::this_thread::sleep_for(std::chrono::nanoseconds(1000000000 / cm->get_update_rate()));
rclcpp::Duration period(std::chrono::nanoseconds(1000000000 / cm->get_update_rate()));

while (rclcpp::ok())
{
rclcpp::Time begin_last = begin;
begin = cm->now();
// wait until we hit the end of the period
end_period += period;
std::this_thread::sleep_for(std::chrono::nanoseconds((end_period - cm->now()).nanoseconds()));

// execute "real-time" update loop
cm->read();
cm->update(begin, begin - begin_last);
current_time = cm->now();
cm->update(current_time, current_time - previous_time);
previous_time = current_time;
cm->write();
rclcpp::Time end = cm->now();
std::this_thread::sleep_for(std::max(
std::chrono::nanoseconds(0),
std::chrono::nanoseconds(1000000000 / cm->get_update_rate()) -
std::chrono::nanoseconds(end.nanoseconds() - begin.nanoseconds())));
}
});

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