[Proposal] New architecture for behavior path planner module #3097
Replies: 6 comments 17 replies
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@xmfcx Do you have any comments ? 😃 |
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I will read it today! |
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@satoshi-ota Can you explain what approving means?
But how often are these sent to an operator? Or is there any other approving mechanism? |
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If we sent every small modification in every small module sent to an operator, operator would have too many requests to evaluate. |
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Thanks for your comment 👍
The approving mechanism already exist in autoware, and documentation is here. Basically, we do NOT assume that it requests approval for a small change in routing, such as a 10 cm path shift. |
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@xmfcx The list of modules using the approval mechanism is:
The purpose of the approval mechanism is to increase safety and efficiency in the development. In detail, it is used for:
By default setting, auto-approver exists and it approves every request as soon as it is requested. You can turn off the auto-approve if needed. It can be tested on the planning_simulator. The concept of the approval should be summarized and writen somewhere in a document, but currently it is not. I'll update the planning design document for the approval. |
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We will wait for comments until next Tuesday 😃 |
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Alright, thanks for all the information that you've provided @TakaHoribe and @satoshi-ota ! This change will help Autoware be more flexible and dropping the behavior-tree dependency will reduce the complexity and maybe even reduce the compile/linking times. Thanks for working on this! ( ^ᵕ^)/ |
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Thank you for all the work and i must say its really exiting to have new architectural changes and design discussions. Although its not my area i am a bit concerned of the timing of this proposal. We are about to finish bus ODD in 3 weeks and there are a bunch of issues in path planning as below: Also after bus odd, there is a plan to start the new ODD for 2023 with so many new challenges in path planning (because the new ODD includes highway multilane driving, roundabouts, underpasses etc.) and where maybe we will have to change or plan to change the architecture in 2-3 months time. So i want to understand whether the timing is right for this new proposal or we should focus our efforts to finish the bus odd issues and propose the architecture considering the 2023 urban & freeway high traffic ODD. |
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Hi @armaganarsln Thanks for your comment, and appologize for my late reply. I think we should focus our efforts to finish the bus odd issues, but a few members in TIER IV, are working on developping the new architecture of planner. We TIER IV would like to implement new behavior path planner proto type that based on proposed architecture at 2023 3/E. So we still have few month to improve and fix current issues. In addition, we plan to keep the current behavior path planner we have been using, and we intend to have a transition phase from the previous architecture to the new architecture. cc @TakaHoribe If you have any other concerns, feel free to comment 😄 |
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My main concerns are two:
Of course everyone free to concentrate on different topics but i think its not fair to the engineers who don't have time to comment on this new architecture module. So could we postpone this item to next month or March and focus on bus odd related issues? |
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I got it. I would like to plan the new architecture developping, taking into account the impact on BUS ODD. cc @mitsudome-r @xmfcx @angry-crab |
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@armaganarsln
This is a valid point. However, this discussion has been there since December 1st. I've also mentioned it in one of the ASWG calls, but we only have Fatih and your reaction so far. If there are engineers who has interest but doesn't have time to look into the details, I would love to see them posting the comment that they want TIER IV to wait for discussion.(Just like you just did in your comment 😄 ) That way, we know that there are people who are interested in the topic and set a call to have a further discussion when they have time. @satoshi-ota |
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@xmfcx @mitsudome-r @mehmetdogru @TakaHoribe NOTE: BT based manager is used as default. And, we TIER IV would like to use this manager in autoware as default in near future. Then, I want to ask you about what we should do before that. I suppose that we TIER IV should...
I want your options about that.
Please feel free to left comments. simplescreenrecorder-2023-04-07_20.13.01.mp4 |
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@satoshi-ota Thank you for working on this! In my opinion, we can make the new manager default one as soon as it passes all the scenarios as you mentioned. After doing this it is a good idea to support BT based manager as well for sometime (duration to be determined) to have a back-up plan just in case if we will have major issues with the new one in different/more complex real life scenarios than the ones we have for simulations. And so hopefully we can complete the manager update transition without any glitch. |
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Hi @mehmetdogru Thanks for your positive comments.
I completely agree with you. Since this is a large update, we should have an alternative plan to use BT based manager in case problems arise, as you said. On the other hand, I think we also need to be careful to decrease maintenance costs since multiple managers coexits. First and foremost, I think it is important for everyone to know how the manager works, so I will make it a priority to maintain the documentation about that. And, I will wait a bit for other member's opinion. |
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I confitmed that new behavior path planner achieve most of all scenarios in awf catalog. And basically, all of the failed scenario that new behavior path planner can't pass are failed on old behavior path planner, too. Then, I think those fails don't related to behavior path planner architecture, and we can transit to new behavior path planner manager. What do you think? |
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How to use the new manager?For now, we can switch the NEW and BT based manager by flag in Cmake file. And, BT based is used by default. cmake_minimum_required(VERSION 3.14)
project(behavior_path_planner)
find_package(autoware_cmake REQUIRED)
autoware_package()
find_package(OpenCV REQUIRED)
find_package(magic_enum CONFIG REQUIRED)
set(COMPILE_WITH_OLD_ARCHITECTURE TRUE)
...What can we do on the new manager?Run two scenarios to compare the behavior of NEW manager with BT based one. Scenario1. need to execute lane change in avoidance manauver.BT based managerSince BT based manager execute all module execlusively, lane change module can't run while avoidance module is running. Then, lane change module has to wait the end of avoidance module process. This issue may cause vehicle stuck and over ride (OR) in worst case. For example, in following scene, lane change can do anything despite of the fact that the goal is on the right side lane and the ego is getting closer.
In the end, the remaining distance for lane change quite a bit short.
new managerOn the other hand, new manager can execute lane change module as soon as the avoidance module decides the output path. So, the ego can execute lane change from the middle of the avoidance path. simplescreenrecorder-2023-04-13_11.20.20.mp4Scenario2. need to execute avoidance in lane change maneuver.BT based managerAs mentioned above, avoidance module can't run while the lane change module is running on BT based manager. In the following scene, the avoidance module do nothing despite of the fact that perception module already detected a parked-vehicle on lane change target lane. And, the avoidance module start running after the ego get quite a bit closer to the vehicle.
new managerAvoidance module can run as soon as the perception module detects objects that should be avoid even if it is the lane change maneuver.
230601268-22a0008c-a53c-41ec-a68f-9d5ce423499d.mp4 |
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@satoshi-ota Could you expand on behavior differences that would occur with this new behavior planner that can't be achieved by running the old behavior tree architecture but having each node in the behavior tree running a separate action client. This would be very similar to how Navigation2 achieves it and would allow for running nodes without blocking each other (by returning the BT::Running instead of Success or Failure) but still maintain the nice UI of Behavior Tree |
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I guess this point would still be tricky though I could see a way of auto generating the string of an XML file based off current priorities and using the |
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Hi @sisaha9 ✋ Thanks for asking and your advice 👍 cc @TakaHoribe
Actually, we think it is not impossible to construct the logic to achieve complex scenarios on Behavior Tree, as you said.
However, if we implement all logic for what we want to do on BT (e.g. change the order of execution between modules according to the situation), the tree would become very complicated and difficult to maitain. Additionaly, we think we can't say that it is definitely appropriate to use BT as an interface for modules, and we have decided to allow designing module and manager specifications without being bound by the BT configuration at one time. |
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I see. Thanks for the clarification @satoshi-ota |
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We TIER IV would like to propose a new architecture for beahvior path planner module.
Background
The current behavior path planner module architecture is working in the following flow/rules:
In short, the current architecture has the following two major limitations:
1. Multiple modules cannot run simultaneously, which makes it difficult to achieve complex use cases (e.g. parked vehicle avoidance during lanechange maneuver).
2. Hierarchies between modules can not be changed in runtime, which can not achieve flexible path generation according to use cases.
To overcome these limitations, we TIER IV would like to propose a new architecture for behavior path planner module. It has two major changes.
a. Modules can be operated in series, allowing the manager the flexibility to change the sequence.
a. The interface for each module is still being explored. At this stage, it is difficult for developers to exploit the advantage of the behavior tree (although it may return to the behavior tree in the future).
Details are described below.
Examples of expected use cases achieved by this proposal
Proposed architecture
documentation here
Overview
The proposed architecture is shown below. The key features are following:
(Reference Path: the path generated from the centerline of road lanelet.)
Pros:
Cons:
Module Interface
All modules outputs two paths.
At first, the running module receives the latest data and path, and outputs the modified path as Candidate Path and RTC Status. The RTC (Request To Cooperate) is a system that asks the operator's approve to change the path (RTC Status), and the operator checks the candidate path and approves the module's path modification (RTC Command). If the path modification is approved, the module outputs the path as Output Path.
Planner manager
There is no update of input/output topics, but there is new planner manager as a subsititute for BehaviorTree. The manager passes the latest subscribed data to the registered modules and activates module(s) if necessary. The activated module first outputs a candidate path, and if the path modification is approved, the module is moved into Approved Modules Stack by planner manager.
How Approved Module Stack works ?
The Approved Modules Stack (yellow block in the above figure) has a vector or queue structure in which approved modules are stored. This block receives the reference path and outputs modified path as the result of the modification by all stored modules. In this time, all modules run in series, and the output of one module is the input of the next module.
How Request Manager works ?
The Request Manager (red block in above figure) passes the latest data to module checks which registered module requests path modification based on the latest modified path of Approved Modules Stack. If several modules request path modification, it selects the one module among them that has the highest priority to be run. In my mind, the algorithm for prioritizing among the modules can be based on following methods, but it can be made richer in the future.
As first step, we TIER IV would like to use the former one, but if this architecture works well as intended, we will try the latter approach.
Process
There are 5 steps in one planning process:
and, loop step1~4 until the following conditions are satisfied.
Thus, dismissed requests in step3 may be selected and the module activated in the next iterate.
Finally, behavior path planner module outputs its modified path and candidate path in Step5. (See flowchart)
Flowchart
Abort/Expire approved module modification
All modules in Approved Modules Stack determine the decision on the need for a path modification based on the assumption that the approved module’s outputs will not change drastically. However, there is a possibility that approved module (e.g. avoidance, lanechange) judges that the modified path is unsafe, and it may revert the changed path or generate another modified path.
In this situation, the paths output by the later modules may also change drastically, so the planner manager removes the module with the drastically path change and all the modules that are stacked at the back of the module. This process is execute in Step1.
Note
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