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Add flag to not send request in BTServiceNode #3431

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Merged
SteveMacenski merged 10 commits into from
Mar 20, 2023
+16 −2
Merged

Add flag to not send request in BTServiceNode #3431

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48217c2
Add flag to not send request in BTServiceNode
Feb 28, 2023
a31b394
rename goal to request
Feb 28, 2023
a68c971
Merge remote-tracking branch 'upstream/main'
Mar 10, 2023
67cf53e
Merge branch 'main' into add-flag-to-not-send-request-BTServiceNode
Mar 17, 2023
3a86c66
Fail if should not send goal
Mar 17, 2023
05fd124
Update nav2_behavior_tree/include/nav2_behavior_tree/bt_service_node.hpp
Mar 20, 2023
f52b108
Update nav2_behavior_tree/include/nav2_behavior_tree/bt_service_node.hpp
Mar 20, 2023
a24277d
.
Mar 20, 2023
60f47bd
fix linter
Mar 20, 2023
b47ddd9
fix CI
tonynajjar Mar 20, 2023
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5 changes: 3 additions & 2 deletions nav2_behavior_tree/include/nav2_behavior_tree/bt_action_node.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -196,9 +196,10 @@ class BtActionNode : public BT::ActionNodeBase
// user defined callback, may modify "should_send_goal_".
on_tick();

if (should_send_goal_) {
send_new_goal();
if (!should_send_goal_) {
return BT::NodeStatus::FAILURE;
}
send_new_goal();
}

try {
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13 changes: 13 additions & 0 deletions nav2_behavior_tree/include/nav2_behavior_tree/bt_service_node.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -131,7 +131,17 @@ class BtServiceNode : public BT::ActionNodeBase
BT::NodeStatus tick() override
{
if (!request_sent_) {
// reset the flag to send the request or not,
// allowing the user the option to set it in on_tick
should_send_request_ = true;

// user defined callback, may modify "should_send_request_".
on_tick();

if (!should_send_request_) {
return BT::NodeStatus::FAILURE;
}
Comment on lines +141 to +143
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@tonynajjar tonynajjar Apr 11, 2023 •
edited
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Looking back at this @SteveMacenski, we now have the use case where we want to not send a request and succeed. E.g. the BT node sees that we are already in the target state, so no need to send a request and succeed.

Would it make sense to implement something like:

      // user defined callback, may modify "should_fail_without_sending_goal_" and "should_succeed_without_sending_goal_".
      on_tick();

      if (should_fail_without_sending_goal_) {
            return BT::NodeStatus::FAILURE;
      }
      if (should_succeed_without_sending_goal_) {
            return BT::NodeStatus::SUCCESS;
      }

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@SteveMacenski SteveMacenski Apr 11, 2023 •
edited
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I think that should be handled in a different BT node, if you read the BTs for AI and Robotics book, the common design pattern is to have a conditional node if a particular objective is complete to skip doing the actual task (e.g. a branch of the tree with a "if ball not in hand, --> then pick up ball" so that if the conditional node checking if the ball is in the hand will trigger or not trigger picking up the ball action)

If that's the case - which it also sounds like you may have (?) the return code for this doesn't matter because that BT node wouldn't be triggered if under the appropriate control flow node. If there's something else you're wanting to do that I'm missing, I'm not opposed to changes, but this is a well understood BT design pattern (should this fit).


future_result_ = service_client_->async_send_request(request_).share();
sent_time_ = node_->now();
request_sent_ = true;
Expand Down Expand Up @@ -243,6 +253,9 @@ class BtServiceNode : public BT::ActionNodeBase
std::shared_future<typename ServiceT::Response::SharedPtr> future_result_;
bool request_sent_{false};
rclcpp::Time sent_time_;

// Can be set in on_tick or on_wait_for_result to indicate if a request should be sent.
bool should_send_request_;
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};

} // namespace nav2_behavior_tree
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