Pause Functionality #28
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Hi @mrceki,
I'm still in the process of reviewing, but I have a quick question to help me understand it better. Please bear with me.
| if (pause_simulation_) { | ||
| // when paused, use the wall clock | ||
| sim_time_ros = node_->get_clock()->now(); | ||
| sim_period = control_period_; | ||
| } | ||
| else { | ||
| // Get the simulation time and period | ||
| auto sim_time = mj_data_->time; | ||
| int sim_time_sec = static_cast<int>(sim_time); | ||
| int sim_time_nanosec = static_cast<int>((sim_time - sim_time_sec)*1000000000); | ||
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| sim_time_ros = rclcpp::Time(sim_time_sec, sim_time_nanosec, RCL_ROS_TIME); | ||
| sim_period = sim_time_ros - last_update_sim_time_ros_; | ||
| } |
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Why do we need to separate these two cases?
I think it might cause a problem, particularly when we resume the simulation, as time will jump (and also go backward).
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I separated the cases to keep controller updates running even when simulation time is frozen. But I'm not completely sure if simulation time really stops when paused. I'll need to double-check that.
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This version does not lead to time jumping as I observed. But it is also unnecessary to separate it in two cases because it's working unlike what I remember about time freezing.
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@sangteak601 I think I found out why I separated in two cases. If you pause the sim without pausing at startup, that's OK. But If we want to pause simulation in startup, controllers cannot be loaded. What is your suggestion on that?
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@sangteak601 I think I found out why I separated in two cases. If you pause the sim without pausing at startup, that's OK. But If we want to pause simulation in startup, controllers cannot be loaded. What is your suggestion on that?
I have done testing and was able to reproduce the issue of controllers not being loaded. One potential solution is to move controller_manager_->update() outside the if (sim_period >= control_period_) condition, similar to how controller_manager_->write() is currently positioned.
However, I am uncertain whether this change might introduce performance overhead, and I am also unsure why I initially placed controller_manager_->write() outside the condition.
Hi!
As discussed in issue #25, this pull request adds pause functionality. You can toggle the pause state via the space bar.
Also, you can trigger pause at startup using the
'pause_simulation': Trueparameter in the launch file.