비평탄 지형에서 이족로봇의 강인한 보행 알고리즘

이보훈(Bo-Hoon Lee),박종한(Jong-Han Park),이창석(Chang-Seok Lee),김용태(Yong-Tae Kim) 大韓電子工學會 2011 電子工學會論文誌-SC (System and control) Vol.48 No.4

이족로봇은 높은 자유도로 인하여 기구적인 불안정성을 내포하고 있기 때문에 보행 시 자세 안정성의 확보가 중요하다. 일반적으로 평지에서는 안정적인 정적 보행이 가능하지만 평지가 아닌 비평탄 지형에서는 보행의 안정성이 현저하게 떨어진다. 본 논문에 서는 비평탄 지형에서 이족로봇의 자세 안정화를 포함한 강인한 보행 방법을 제안하였다. 이족로봇의 중앙에 장착된 자이로 센서와 가속도 센서 값을 기반으로 보행 순간마다 센서 값을 감지하여 로봇 몸체의 기울어진 각도를 인식하여 보행 자세를 안정화하는 강인 보행 알고리즘을 설계하였다. 비평탄 지형 보행은 로봇의 기울어진 각도를 인식하여 그 상황에 맞게 관절 각도를 변화시켜 이족로봇 상체의 각도가 평지보행에서와 같도록 하체관절의 각도를 보정하여 보행에서의 안정성을 높였다. 제안된 보행알고리즘은 실제 제작된 이족로봇을 사용하여 비평탄 지형에서 실험하여 제안된 보행 알고리즘의 성능을 검증하였다. Biped robot with high DOF has instability in mechanism. Therefore, it is important to guarantee walking stability of biped robot. Biped robot can stably walk on the flat ground using static walking patterns. However, walking stability of robot becomes increasingly worse on the uneven terrain. In the paper, we propose a robust walking algorithm of biped robot with motion stabilization to solve the problem The proposed algorithm was designed to stabilize walking motions based on the inclination of robot body using a gyro sensor and a accelerometer equipped in the center of the upper body. If unstable motions are recognized, angles of each joints are modified to increase stability by using compensation of angles of lower legs. The experimental results show that biped robot performs stable walking on the uneven terrain.

영상 기반 센서 융합을 이용한 이족로봇에서의 환경 인식 시스템의 개발

송희준(Heejun Song),이선구(Seonggu Lee),강태구(Taegu Kang),김동원(Dongwon Kim),서삼준(Sam-Jun Seo),박귀태(Gwi-Tae Park) 대한전기학회 2006 정보 및 제어 심포지엄 논문집 Vol.2006 No.1

This paper discusses the method of vision based sensor fusion system for biped robot walking. Most researches on biped walking robot have mostly focused on walking algorithm itself. However, developing vision systems for biped walking robot is an important and urgent issue since biped walking robots are ultimately developed not only for researches but to be utilized in real life. In the research, systems for environment recognition and tele-operation have been developed for task assignment and execution of biped robot as well as for human robot interaction (HRI) system. For carrying out certain tasks, an object tracking system using modified optical flow algorithm and obstacle recognition system using enhanced template matching and hierarchical support vector machine algorithm by wireless vision camera are implemented with sensor fusion system using other sensors installed in a biped walking robot. Also systems for robot manipulating and communication with user have been developed for robot.

인간의 COG 궤적의 분석을 통한 5-link 이족 로봇의 보행 패턴 생성

김병현(Byounghyun Kim),한영준(Youngjoon Han),한헌수(Hernsoo Hahn) 한국정보과학회 2009 정보과학회논문지 : 소프트웨어 및 응용 Vol.36 No.2

인간이 최소 에너지를 소비하면서 자연스럽고 안정된 상태로 보행한다는 것에 착안하여, 본 논문은 인간 보행의 COG 궤적을 분석함으로써 인간형 이족로봇의 자연스러운 보행에 관한 연구를 수행한다. 이를 위해서 본 논문은 sagittal plane과 frontal plane상의 보행 영상으로부터 계측된 COG 궤적을 고려함으로써 안정적이고 에너지를 최소화하는 자연스러운 이족로봇의 보행 패턴을 생성한다. 인간과 이족로봇은 기구학적인 형태는 유사하지만 자유도에 있어 많은 차이를 보이기 때문에 추출된 인간 관절의 회전력을 이족로봇에 바로 적용할 수 없다. 본 논문에서는 인간의 보행패턴으로부터 계측된 각 관절의 회전력과 인간의 COG 궤적으로부터 계산된 ZMP을 이용하는 적응적 보행 패턴 생성 GA 알고리즘을 통해 5-link 이족로봇 모델의 보행패턴을 생성한다. 제안된 알고리즘은 인간의 각 관절의 회전력과 ZMP 궤적을 고려하기 때문에 인간과 같이 유연하고 에너지 소비를 최소화하는 인간형 이족로봇의 보행패턴을 생성한다. 본 논문은 역기구학을 이용한 일반적인 방법과 제안하는 방법에 의해 생성된 보행 패턴을 각각 5-link 이족로봇 모델에 적용하여 시각적인 측면과 에너지 효율측면에서 평가함으로써 제안하는 알고리즘의 우수성을 입증하였다. Based on the fact that a human being walks naturally and stably with consuming a minimum energy, this paper proposes a new method of generating a natural gait of 5-link biped robot like human by analyzing a COG(Center Of Gravity) trajectory of human's gait. In order to generate a natural gait pattern for 5-link biped robot, it considers the COG trajectory measured from human's gait images on the sagittal and frontal plane. Although the human and 5-link biped robot are similar in the side of the kinematical structure, numbers of their DOFs(Degree Of Freedom) are different. Therefore, torques of the human's joints cannot are applied to robot's ones directly. In this paper, the proposed method generates the gait pattern of the 5-link biped robot from the GA algorithm which utilize human's ZMP trajectory and torques of all joints. Since the gait pattern of the 5-link biped robot model is generated from human's ones, the proposed method creates the natural gait pattern of the biped robot that minimizes an energy consumption like human. In the side of visuality and energy efficiency, the superiority of the proposed method have been improved by comparative experiments with a general method that uses a inverse kinematics.

충격 감소 및 중력 보상을 위한 이족보행로봇의 무릎-골반 관절 설계

김영민(Young-Min Kim),김용태(Yong-Tae Kim) 대한전기학회 2015 전기학회논문지 Vol.64 No.1

In the paper, a design method of knee and pelvis joint in the biped robot is proposed for shock absorption and gravity compensation. Similarly to the human’s body, the knee joints of the biped robot support most body weight and get a shock from the landing motion of the foot on the floor. The torque of joint motor is also increased sharply to keep the balance of the robot. Knee and pelvis joints with the spring are designed to compensate the gravity force and reduce the contact shock of the robot. To verify the efficiency of the proposed design method, we develope a biped robot with the joint mechanism using springs. At first, we experiment with the developed robot on the static motions such as the bent-knee posture both without load and with load on the flat ground, and the balance posture on the incline plane. The current of knee joint is measured to analyze the impact force and energy consumption of the joint motors. Also, we observe the motor current of knee and pelvis joints for the walking motion of the biped robot. The current responses of joint motors show that the proposed method has an effect on shock reduction and gravity compensation, and improve the energy efficiency of walking motions for the biped robot.

보행로봇의 시뮬레이터개발에 의한 보행패턴계획의 기초적 연구

박창용(Chang-Young Park),권현규(Hyun-Kyu Kweon) 한국기계가공학회 2010 한국기계가공학회지 Vol.9 No.6

In this paper, a new simulator of the biped robot for planning walking patterns was showed. And this simulator(MHBiped) is able to not only visualize the plan of patterns but also verify whether a biped robot design is suitable. In addition, MHBipd can modify various kinds of walking parameters and the trajectory of biped robot. Therefore, a new biped robot can be designed easily by the this simulator before you apply to a robot. As a result, a well-balanced parameters of walking patterns watching the movement of CG and ZMP can be obtained. Walking patterns should be changed according to both the existence of obstacles and conditions of ground and it can be described by the trajectory of hip and ankles. All those trajectorys can be also obtained by the cubic spline functions and the way of modeling walking patterns. The results of simulator, the movement function of CG and ZMP, the cubic spline functions and modeling of biped robot were introduced in this paper. And the effectiveness of this simulator was confirmed by the simulations.

Biped robot state estimation using compliant inverted pendulum model

Bae, Hyoin,Oh, Jun-Ho Elsevier 2018 Robotics and autonomous systems Vol.108 No.-

<P><B>Abstract</B></P> <P>This study proposes a biped robot state estimation framework based on a compliant inverted pendulum model and a robust state estimator. A proper model that can express the key physical characteristics while considering limited computing power should be defined for the biped robot state estimation. A biped robot’s limited structural stiffness and relatively long legs compared with the cross section of the body lead to undesired flexibility. However, the models used in previous research are either not suitable for state estimation or too simple to express the essential characteristics of the biped robot. A compliant inverted pendulum model is adopted herein to enhance the estimation accuracy. This model is made by adding a virtual spring and a damper to the conventional inverted pendulum. The additional elements represent the mechanical deformation and the undesired flexible movement. Adopting this model makes it possible to reflect the important characteristics of the biped robot while taking advantage of the merits of the single-mass model. In addition, a robust state estimator that we previously proposed is adopted to compensate for the estimation error caused by the modeling error. Using these two factors, the improved COM-kinematics estimate is obtained with respect to the existing simple-model-based biped state estimators.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Humanoid robot has the flexibility feature and this disturbs the state estimation. </LI> <LI> A compliant inverted pendulum model is adopted to reflect the robot’s key feature. </LI> <LI> The previously developed robust estimator is utilized to enhance the performance. </LI> <LI> Compliant model and robust estimator based state estimation framework is suggested. </LI> </UL> </P>

인간 관절 에너지 분석을 통한 이족로봇의 자연스러운 보행 제어

하승석(Seungsuk Ha),한영준(Youngjoon Han),한헌수(Hernsoo Hahn) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.2

This paper proposes a method of adaptively generating a gait pattern of biped robot. The gait synthesis is based on human"s gait pattern analysis. The proposed method can easily be applied to generate the natural and stable gait pattern of any biped robot. To analyze the human"s gait pattern, sequential images of the human"s gait on the sagittal plane are acquired from which the gait control values are extracted. The gait pattern of biped robot on the sagittal plane is adaptively generated by a genetic algorithm using the human"s gait control values. However, gait trajectories of the biped robot on the sagittal plane are not enough to construct the complete gait pattern because the biped robot moves on 3-dimension space. Therefore, the gait pattern on the frontal plane, generated from Zero Moment Point (ZMP), is added to the gait one acquired on the sagittal plane. Consequently, the natural and stable walking pattern for the biped robot is obtained, as proved by the experiments.

칼만예측기의 ZMP 상태추정을 통한 이족로봇의 균형제어기법

김상범(SangBum Park),한영준(Youngjun Han) 한국지능시스템학회 2006 한국지능시스템학회논문지 Vol.16 No.5

본 논문은 칼만필터를 이용한 ZMP의 다음 상태 예측을 통한 새로운 이족로봇의 균형제어기법을 제안한다. 일반적으로 이족로봇의 동역학 모델은 3D-LIPM(3D-Linear Inverted Pendulum Mode)에 의해 수학적으로 근사화되지만, 이는 로봇의 동역학적 특성을 완벽하게 표현할 수 없다. 이족로봇의 안정성은 ZMP(Zero Moment Point) 위치가 안정영역에 존재하는 경우에 안정성이 보장된다. 그리고 로봇 구조와 그 모델 사이의 내재된 오차는 로봇의 안정성에 영향을 끼칠 수 있다. 그러므로 본 논문에서 제안하는 균형제어기법은 내부 오차를 줄일 수 있으며, 적절한 로봇의 제어가 가능하다. 제안된 균형제어기법의 실험은 다양한 상황을 포함한 가상의 공간상에서 모의실험되었다. This paper proposes a novel balance control scheme of a biped robot to predict the next position of ZMP using Kalman Filter. The mathematical model of the biped robot is generally approximated by 3D-LIPM(3D-Linear Inverted Pendulum Mode), but it cannot completely express the robot's dynamics. The stability of the biped robot depends on whether the ZMP(Zero Moment Point) position is in the stability region or out of. And the internal error between the robot mechanism and its model could affect the stability of a robot. Therefore, the proposed balance control not reduces the internal error, but also timely generates the proper control. The experiment of the proposed balance control is simulated on the virtual workspace where the biped robot may encounter with various difficulties.

인간의 보행 회전력의 주파수 특징 분석을 이용한 이족로봇의 적응적 보행 패턴 생성

하승석(Seung-Suk Ha),한영준(Young-Joon Han),한헌수(Hernsoo Hahn) 한국지능시스템학회 2008 한국지능시스템학회논문지 Vol.18 No.1

본 논문에서는 이족로봇의 자연스러운 보행 패턴을 생성하기 위해 인간의 보행 회전력(torque)을 주파수 영역에서 분석하고 분석된 데이터를 이용하여 적응적으로 이족로봇의 보행패턴을 생성하는 기법을 제안한다. 인간의 보행 회전력은 시간영역에서 복잡한 형태를 가지므로 DCT(Discrete Cosine Transform)를 이용하여 주파수영역으로 변환시켜 분석한다. 주파수 영역에서 얻어진 보행 회전력의 특징을 이용하여 이족로봇의 sagittal plane에서의 보행패턴을 생성한다. 또한 이족로봇의 안정적인 보행 패턴을 생성하기 위하여 동적 평형 상태임을 판단할 수 있는 Zero Moment Point(ZMP)해석을 통해 frontal plane상의 보행패턴을 생성하여 3차원 공간상의 안정적이고 인간과 같이 자연스러운 보행 패턴을 생성했다. This paper proposes a method of adaptively generating a gait pattern of biped robot. The gait synthesis is based on human's gait pattern analysis. The proposed method can easily be applied to generate the natural and stable gait pattern of any biped robot. To analyze the human's gait pattern, sequential images of the human's gait on the sagittal plane are acquired from which the gait control values are extracted. The gait pattern of biped robot on the sagittal plane is adaptively generated by a genetic algorithm using the human's gait control values. However, gait trajectories of the biped robot on the sagittal plane are not enough to construct the complete gait pattern because the biped robot moves on 3-dimension space. Therefore, the gait pattern on the frontal plane, generated from Zero Moment Point (ZMP), is added to the gait one acquired on the sagittal plane. Consequently, the natural and stable walking pattern for the biped robot is obtained.

이족로봇 플랫폼을 위한 동체탐지

강태구(Taekoo Kang),황상현(Sanghyun Hwang),김동원(Dongwon Kim),박귀태(Guitae Park) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.10

This paper discusses the method of moving object detection for biped robot walking. Most researches on vision based object detection have mostly focused on fixed camera based algorithm itself. However, developing vision systems for biped walking robot is an important and urgent issue since biped walking robots are ultimately developed not only for researches but to be utilized in real life. In the research, method for moving object detection has been developed for task assignment and execution of biped robot as well as for human robot interaction (HRI) system. But these methods are not suitable to biped walking robot. So, we suggest the advanced method which is suitable to biped walking robot platform. For carrying out certain tasks, an object detecting system using modified optical flow algorithm by wireless vision camera is implemented in a biped walking robot.