論文 / 著書情報
Article / Book Information
題目(和文)

時相論理を用いたタスク表現に対するロボットシステムの軌道最適化と制御

Title(English)

Trajectory Optimization and Control of Robot Systems with Temporal
Logic Tasks

著者(和文)

徳田俊平

Author(English)

Shumpei Tokuda

出典(和文)

学位:博士(工学),学位授与機関:東京工業大学,
報告番号:甲第12692号,授与年月日:2024年3月26日,
学位の種別:課程博士,
審査員:山北 昌毅,三平 満司,倉林 大輔,田中 正行,畑中 健志

Citation(English)

Degree:Doctor (Engineering),
Conferring organization: Tokyo Institute of Technology,
Report number:甲第12692号,
Conferred date:2024/3/26,
Degree Type:Course doctor,Examiner:,,,,

学位種別(和文)

博士論文

Category(English)

Doctoral Thesis

種別(和文)

論文要旨

Type(English)

Summary

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（博士課程）Doctoral Program論 文 要 旨ＴＨＥＳＩＳ ＳＵＭＭＡＲＹ

系 ・ コ ース：
Department of, Graduate major in

システム制御システム制御学生氏名：
Student’s Name

德田 俊平系
コース

申 請 学 位 （ 専 攻分 博士野）：Doctor of（工学）Academic Degree Requested

審査員主査：
Chief Examiner

山北 昌毅 准教授

要旨（英文 800 語程度）
Thesis Summary （approx.800 English Words ）In recent years, robots play increasingly important roles in society, not only in the industrial
field but also in the service industry. With the spread of robots, opportunities for nonprofessionals are increasing to operate robots and introduce them to services. However, teachingrobots to perform desired tasks safely is difficult, and this is one of the obstacles to theintroduction of robots. One of the reasons for the difficulty in teaching tasks to robots is theneed to simultaneously consider the logical consistency of the task and its feasibility considering
the dynamic characteristics of the robot. Therefore, we need to use a control architecture thatconsiders simultaneously both.
The use of modal logic such as linear temporal logic (LTL) and signal temporal logic (STL)
has attracted much attention as a way of logically representing tasks in robot systems. These modallogics represent the properties of sequences of state transitions. By describing the rules andconstraints of a task as logical expressions, we can determine in advance whether the assumed task
is logically sound or not. When generating a sequence of state transitions satisfying the temporal
logic on a robot system, we need to generate robot trajectories on an abstracted system, rather thanon the actual robot system.
In this case, depending on the state and the definition of the approximated system, theextent to which the abstracted system can emulate the characteristics of the actual robot systemdiffers. In addition, the method of generating robot trajectories differs depending on how theabstracted system is constructed. Therefore, the nonlinearity of the abstracted system and how it isconstructed are important depending on the actual robot systems or tasks. Especially, when thetrajectory optimization is formulated as a mixed integer programming problem, it is necessary toconstruct a dynamical linear system that emulates the dynamical characteristics of the actual robot
as an approximated system.
To achieve tasks, we need to control the actual system based on trajectories generated by
the abstracted system. Control methods for satisfying tasks expressed as temporal logic
specifications include model predictive control (MPC) and control barrier functions (CBFs). CBFs areused as constraints in determining control inputs to keep the system trajectory within a certain
region, and the constrained optimization problem with CBFs can be formulated as a quadratic
programming problem, which requires less computation time than the nonlinear MPC. In designing acontroller to achieve tasks represented by temporal logic specifications using CBFs, the issue is
how to set up the CBFs. In the case of a task with a time limit expressed in STL, the design methodof CBFs proposed in the previous studies requires several processes to design the CBF from therobustness functions of STL. Therefore, we propose a new design method for CBFs. Furthermore, there
are cases in which robots cannot achieve a given task with the task plans. Especially, if there aremultiple robots, the robots need to change their motions to achieve the task considering the otherrobots.
In this paper, we propose trajectory optimization methods and control methods for robotsystems for tasks expressed as temporal logic specifications. We focus on the task represented bysyntactically co-safe LTL, generate trajectories in response to their tasks, and control robots.
The high-level controller defines an abstracted robot system for the actual robot system. We
generate trajectories and motions for this abstracted system to achieve tasks expressed by LTL orSTL specifications by optimization. Then, the extent to which the abstracted system can emulate theactual robot depends on the abstraction method of the abstracted system. Therefore, we discuss
abstraction methods for robot systems. In addition, we show that we can compute trajectories thatsatisfy the given temporal logic specifications for the abstracted system. Furthermore, we propose atrajectory optimization method for tasks involving external events represented by event-based STL
specifications.
The low-level controller uses the task plans and trajectories generated by the high-level
controller to control the actual robot systems. In this paper, we propose a control method thatconsiders time constraints to satisfy a given temporal logic specifications using CBFs. In addition,
we also consider methods to represent trajectories as distributions, and to update the distributions
based on the observation information obtained during the operation to change the motions.

備考 : 論文要旨は、和文 2000 字と英文 300 語を 1 部ずつ提出するか、もしくは英文 800 語を 1 部提出してください。
Note : Thesis Summary should be submitted in either a copy of 2000 Japanese Characters and 300 Words (Engｌish) or 1copy of 800
Words (English).
注意：論文要旨は、東工大リサーチリポジトリ（T2R2）にてインターネット公表されますので、公表可能な範囲の内容で作成してください。
Attention: Thesis Summary will be published on Tokyo Tech Research Repository Website (T2R2).