Cited 0 time in webofscience Cited 0 time in scopus

Series Elastic Actuators-Driven 3-DOF Parallel Robot for Dynamic Human Interaction

Title
Series Elastic Actuators-Driven 3-DOF Parallel Robot for Dynamic Human Interaction
Translated Title
사람과의 역동적 상호작용을 위한 탄성구동기 기반 3자유도 병렬로봇
Authors
Hyunwook Lee
DGIST Authors
Hyunwook Lee; Sehoon Oh; Jee-Hwan Ryu
Advisor(s)
오세훈
Co-Advisor(s)
Jee-Hwan Ryu
Issue Date
2022
Available Date
2022-03-08
Degree Date
2022/02
Type
Thesis
Keywords
Series Elastic Actuator, Parallel Robot, Force Control, Impedance control, Work-space Control
Description
Series Elastic Actuator, Parallel Robot, Force Control, Impedance control, Work-space Control
Abstract
This paper proposes a novel parallel robot – Virtual Ground Robot (VGR) - that is driven by three Series Elastic Actuators (SEAs) to interact with a human. For developing the robot, Reaction Force-sensing Series Elastic Actuator (RFSEA) which enables accurate force control is applied as the actuator system, and the parallel structure is applied as the mechanism to generate a large force. The control algorithms are introduced for RFSEA to achieve high force performance and to render desired impedance. To guarantee the stability of the controller with the unknown environment, the passivity concept is applied and analyzed in the frequency domain. Utilizing the passivity analysis, the new Passivity Observer and Passivity Controller (POPC) is introduced to relax the passivity violation, which preserves the passivity while achieving the higher desired stiffness. All analyses developed to control RFSEA are extended to the VGR. The VGR provides a virtual ground on which a human can stand on and interact in three directions: the pitch, the roll and the height directions. Kinematics and statics of the VGR are theoretically analyzed, which validate that the VGR mechanism can achieve wide torques and impedance range compared to the existing 3-RPS mechanisms. And the Spatial POPC for VGR is designed to dissipate energy and relax the passivity violation in the work-space. The developed VGR is utilized as a device to measure and train the balance of a humana human can stand on the VGR, and the balance-related values such as force, position, and the center of pressure are observed. The features and performance of the developed robot are theoretically examined and validated through experiments. |본 논문은 인간과 상호 작용을 위한 세 개의 직렬탄성구동기로 구동되는 새로운 병렬 로봇인 Virtual Ground Robot (VGR)을 제안한다. 로봇 개발을 위해 구동 시스템으로 정확한 힘 제어가 가능한 Reaction Force-sensing Series Elastic Actuator (RFSEA)를 적용하고, 큰 힘을 발생시키는 메커니즘으로 병렬 구조를 적용했다. RFSEA에 대한 제어 알고리즘이 도입되어 높은 힘 성능을 달성하고 원하는 임피던스를 구현한 다. 알 수 없는 환경과의 접촉에서도 컨트롤러의 안정성을 보장하기 위해 주파수 영역에서 수동성 개념을 적용하여 분석한다. 수동성 분석을 활용하여 수동성 위반을 완화하기 위해 새로운 수동성 관찰자 및 수동성 컨트롤러가 도입되어 원하는 더 높은 강성을 달성하면서 동시에 수동성을 유지하게 한다. RFSEA를 제어하기 위해 개발된 모든 분석은 VGR로 확장된다. VGR은 피치, 롤, 높이 방향의 세 가지 방향으로 사람이 서서 상호작용할 수 있는 가상의 지면환경을 제공한다. VGR의 운동학 및 정역학을 이론 적으로 분석하여 VGR의 메커니즘이 기존 3-RPS 메커니즘에 비해 넓은 토크 및 임피던스 범위를 달성할 수 있음을 검증한다. 그리고 VGR을 위한 공간상의 수동성 제어기는 작업 공간에서 에너지를 소산시키고 수동성 위반을 완화하도록 설계된다. 개발된 VGR은 인간의 균형을 측정하고 훈련하는 장치로 활용된다. 사람이 VGR 위에 설 수 있으며 힘, 위치, 압력 중심 등 균형 관련 값이 관측된다. 개발된 로봇의 기능과 성능을 이론적으로 분석하고 실험을 통해 검증한다.
Table Of Contents
Ⅰ. Introduction 1 1.1 Parallel Mechanism for Spatial Motion 3 1.2 Wide Impedance Range for Human Balance Assessment 5 Ⅱ. Dynamic Model of Series Elastic Actuator 8 Ⅲ. Actuator Control of RFSEA 10 3.1 Force control using SEA 10 3.1.1 Disturbance Observer Design for SEA 11 3.1.2 Design of Reduced Order Disturbance Observer 13 3.2 Impedance Control 18 Ⅳ. Actuator Passivity of RFSEA 22 4.1 Passivity Analysis Depending on Energy Ports 23 4.1.1 Analysis of Passivity Condition at Load Port Using Frequency Characteristics 26 4.1.2 Effect of Load Damping and D-gain on Maximum Achievable Stiffness 29 4.2 Passivity Observer and Passivity Controller for SEA 30 4.2.1 Passivity Observer and Passivity Controller 30 4.2.2 Limitation of Passivity Controller for Rendering Desired Damping 32 4.2.3 Design of Passivity Controller based on Load Damping Control 34 4.3 Experimental Validation of Passivity Control for SEA 37 Ⅴ. Kinematics of Parallel Robot 45 5.1 Configuration of Virtual Ground Robot 46 5.2 Reaction Force-Sensing SEA 48 5.3 Kinematics of VG-space and Joint Space 49 5.4 Jacobian for VG-space and Joint Space 52 5.5 Features of VGR Compared to 3-RPS Mechanism 55 5.6 Angle of triangular link to maximize torque of VGR leg 59 Ⅵ. Spatial Control of VGR 61 6.1 Spatial Force Control of Virtual Ground Robot 61 6.2 Spatial Impedance Control 62 6.3 Analysis of Impedance Range in the VG-space 63 6.4 Performance of Spatial Impedance Rendering in VG-space 67 6.5 Spatial Passivity Control 70 Ⅶ. Interaction with a Human participant using VGR 80 7.1 Center of Pressure Estimation using SEA Force Measurement 80 7.2 Interaction with a Human participant using VGR Spatial Impedance 81 7.3 Pilot tests with human participants for balance assessment 85 Ⅷ. Conclusion 88 References 93 요약문 101
URI
http://dgist.dcollection.net/common/orgView/200000597297
http://hdl.handle.net/20.500.11750/16325
DOI
10.22677/thesis.200000597297
Degree
Doctor
Department
Robotics Engineering
University
DGIST
Related Researcher
  • Author Oh, Sehoon MCL(Motion Control Lab)
  • Research Interests Research on Human-friendly motion control; Development of human assistance;rehabilitation system; Design of robotic system based on human musculoskeletal system; Analysis of human walking dynamics and its application to robotics; 친인간적인 운동제어 설계연구; 인간 보조;재활 시스템의 설계 및 개발연구; 인간 근골격계에 기초한 로봇기구 개발연구; 보행운동 분석과 모델 및 로봇기구에의 응용
Files:
There are no files associated with this item.
Collection:
Department of Robotics and Mechatronics EngineeringThesesPh.D.


qrcode mendeley

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE