Survey on: Formalisms for Robotic Mission Specification and Execution: A Comparative Analysis

Introduction

We are a team of software engineers investigating how different modeling formalisms support the specification and execution of robotic missions.

Goal of the study

The goal of the study is to analyze four formalisms, namely Behavior Trees (BTs), State Machines (SMs), Hierarchical Task Networks (HTNs), and the Business Process Model and Notation (BPMN), from a practical perspective, to understand the control structures and the mission concepts they offer, their expressiveness in effectively supporting the modeling of robotic missions, and the tools supporting them.

This survey aims to validate the results of our study by gathering expert feedback on the correctness, completeness, and applicability of our findings. In particular, we ask you to review a subset of results related to the formalism(s) in which you have expertise and to evaluate whether our characterization, expressivity analysis, and identified strengths and weaknesses accurately reflect current practice in robotics.

Data processing

Any personal information will be removed during analysis and will not appear in any publications or presentations. Only the research team will have access to contact data, which will be used solely for study-related communication.

Ethical aspects

No personal, sensitive, or potentially harmful information is collected. Participation is voluntary, and no risks or direct benefits are expected. Your responses are anonymous and will be used solely for academic research purposes.

Consent

Your participation is voluntary and based on informed consent. You may withdraw at any time by closing the survey before submission. Upon request, all data associated with you will be deleted and excluded from any analysis or publication.

Contact Information

If you have any questions or concerns about the study, please contact us at:

General Information

Expertise with the Formalisms

You will be asked to evaluate the analysis we conducted only on the formalisms you selected to be more familiar with (expertise ≥ 3).

Part 1: Modeling of Control Structures and Mission Concepts

How can control structures and mission concepts be modeled with the formalisms?

In this part we analyze:

In the following, we show the control structures we identified for each of the formalisms and how the mission concepts are mapped with the constructs offered by the formalisms.

Behavior Trees
Elements and example
Behavior Trees elements overview
Behavior Trees elements overview
Example of a Behavior Tree
Example of a Behavior Tree
Control Structures
Mission Concepts
State Machines
Elements and example
State Machines elements overview
State Machines elements overview
Example of a State Machine
Example of a State Machine
Control Structures
Mission Concepts
HTNs
Elements and example
HTN elements overview
HTN elements overview
Example of a HTN
Example of a HTN
Control Structures
Mission Concepts
BPMN
Elements and example
BPMN elements overview
BPMN elements overview
Example of a BPMN process
Example of a BPMN process
Control Structures
Mission Concepts

Part 2: Expressiveness analysis, strengths, and weaknesses

What are the peculiarities and limitations of modeling missions with the formalisms?

In this part we analyze:

Expressiveness analysis

We classified the expressiveness of the formalisms into three categories:

  • Full support (), if the formalism provides either native constructs (i.e., elements, operators, or control structures) associated with the concern, or modeling patterns to express it, allowing its modeling to be unambiguous and consistent across the missions without requiring workarounds;
  • Partial support (), if the formalism does not provide an explicit or dedicated construct to express the concern, but it can still be modeled indirectly through workarounds or ad hoc solutions that leverage other constructs;
  • No support (), if the formalism can not express the concern, neither directly nor through workarounds, hence requiring the realization of such concern using external mechanisms or by realizing it at a different abstraction level.

The following table reports our evaluation of the support each formalism offers in expressing the mission concerns. means full support, means partial support, means no support. Click on the icon to see a brief description of each concern.

Please answer to the following questions only considering the formalisms you are more familiar with (expertise ≥ 3).


BTs strengths & weaknesses
SMs strengths & weaknesses
HTNs strengths & weaknesses
BPMN strengths & weaknesses

Part 3: Supporting tools Analysis

Which and to what extent publicly available tools support the formalisms?

In this part we analyze the ecosystem of tools supporting each formalism. The analysis examines whether there are tools providing modeling, execution, monitoring, debugging, or planning functionalities for the formalisms. We only considered actively mantianed tools.

  • Modeling refers to graphical or structured interfaces for creating and visualizing mission specifications.
  • Execution denotes a tool’s ability to interpret and run a model, either standalone or within ROS.
  • Monitoring concerns the provision of real-time information on mission status during execution.
  • Debugging supports diagnosing undesired behaviors through trace visualization, state inspection, and event logging.
  • Planning refers to the automatic generation of task decompositions or action sequences.

Behavior Trees (BT)
State Machines (SM)
Hierarchical Task Networks (HTN)
BPMN

Final Comments

Contact Information

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