• 한국기계가공학회지
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• 제20권9호
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• pp.97-103
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• 2021

In this paper, an omni wheel-based electric wheelchair is proposed that can achieve safe and convenient movement and can improve the convenience of living for mobility-impaired people who cannot move on their own. Generally, mobility-impaired people are afflicted with physical health issues such as pain and secondary body deformities because they often remain seated in wheelchairs for long periods of time. Hence, an electric wheelchair is required whose posture can be changed and whose size can be adjusted according to the user's body type. Such a wheelchair should also facilitate easy change of direction (even in a narrow space) for convenient movement. In this paper, an electric wheelchair featuring omni wheels is proposed that allows posture transformation and facilitates movement in a narrow space. It is believed that the proposed wheelchair can aid in enhancing the convenience of living for mobility-impaired people.

• 한국정밀공학회지
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• 제30권1호
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• pp.18-23
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• 2013

Omni-directional robot is a typical holonomic constraint robot that has three degrees of freedom movement in 2D plane. In this study, a new omni-directional robot whose wheels are arranged in radial directions was proposed to improve driving performance of the robot. Unlike a general omni-directional robot whose wheels were arranged in a circumferential direction, moments do not arises in the proposed robot when the robot travels in a straight line. To analyze driving performance, dynamic modeling of the omni-directional robot, which considers friction and slip, was carried out. By friction measurement experiments, the relationship between dynamic friction coefficient and relative velocity was derived. Dynamic friction coefficient according to the angle difference between robot travel direction and wheel rotation direction was also obtained. By applying these results to the dynamic model, driving performance of the robot was calculated. As a result, the proposed robot was 1.5 times faster than the general robot.

• International Journal of Control, Automation, and Systems
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• 제6권1호
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• pp.86-100
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• 2008

Most of the previously employed dynamic modeling approaches, including Natural Orthogonal Complement Algorithm, have limitations on their application to the mobile robot, specifically at singular configurations. Also, in their dynamic modeling of mobile robots, wheel dynamics is usually ignored assuming that its dynamic effect is negligibly small. As a remedy for this, a singularity-free operational space dynamic modeling approach based on Lagrange's form of the D' Alembert principle is proposed, and the singularity-free characteristic of the proposed dynamic modeling is discussed in the process of analytical derivation of the proposed dynamic model. Then an accurate dynamic model taking into account the wheel dynamics of the omni-directional mobile robot is derived, and through simulation it is manifested that the effect of the wheel dynamics on the whole dynamic model of the mobile robot may not be negligible, but rather in some cases it is significantly large, possibly affecting the operational performances of dynamic model-based control algorithms. Lastly, the importance of its accurate dynamic model is further illustrated through impulse analysis and its simulation for the mobile robot.

• 한국생산제조학회지
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• 제24권2호
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• pp.141-147
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• 2015

In this study, a position control algorithm for an omni-directional mobile robot based on Mecanum wheels was introduced and experimentally evaluated. Multiple ultrasonic sensors were installed around the mobile robot to obtain position feedback. Using the distance of the robot from the wall, the position and orientation of the mobile robot were calculated. In accordance with the omni-directional velocity generation mechanism, the velocity kinematics between the Mecanum wheel and the mobile platform were determined. Based on this formulation, a simple and intuitive position control algorithm was suggested. To evaluate the control algorithm, a test bed composed of artificial walls was designed and implemented. While conventional control algorithms based on normal wheels require additional path planning for two-dimensional planar motion, the omni-directional mobile robot using distance sensors was able to directly follow target positions with the simple proposed position feedback algorithm.

• 융합신호처리학회논문지
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• 제5권4호
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• pp.308-316
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• 2004

실내 환경에서 자율이동 로봇은 방향의 전환과 움직임에 있어서 많은 제약이 따른다. 본 연구는 이런 제약을 해결하기 위하여 수평, 대각이동이 가능한 Omni-Directional Wheel을 로봇 구동부에 적용하였다. 하지만 Slip에 의해서 동력을 얻는 Omni Directional Wheel 구동방식은 Slip에 의한 오차가 발생하는 문제점이 있었다. 이 문제점을 해결하기 위해 개발된 Slip 보정 알고리즘은 하나의 타일을 지날 때마다 외곽선을 추출하고, 추출된 외곽선과 로봇의 절대방위가 이루는 각도를 비교하여 오차가 발생할 경우 로봇의 절대방위를 수정하게 한다. 또한 로봇은 보안기능과 서비스 기능을 수행한다. 보안기능은 차 영상을 이용하여 움직임을 감지한다. 서비스 기능으로는 로봇에 입력되는 영상을 일반사용자에게 다중전송 하고, 간단한 이동명령이 있다. 본 연구에서 제안한 로봇 시스템은 실제 사무실에서 사용가능한 하나의 모델이 될 수 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.443-444
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• 2013

• 전자공학회논문지
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• 제53권4호
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• pp.149-155
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• 2016

본 논문에서는 운전자의 체중 이동을 활용한 메카넘 휠 기반 전방향 전동 보드 제어 방법을 제안한다. 운전을 위한 별도의 운전 장치를 사용하지 않으며, 다수의 센서를 활용하여 측정한 체중 분포로부터 무게 중심의 위치를 구하여 전방향 전동 보드의 병진 운동과 회전 운동의 3 자유도 운전 명령을 생성한다. 체중 이동은 운전 명령으로 반영됨과 동시에 관성력을 극복하기 위한 운전자의 동작과 일치하여 직관적인 장점이 있다. 전체 제어 구조를 제시하며, 실험에 적용하여 제안된 방식의 타당성을 확인한다.

• 로봇학회논문지
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• 제10권4호
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• pp.186-192
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• 2015

This paper proposes a robust balance and driving control for omni-directional ball robot(generally called ball-bot) with two axis mecanum wheel. Slip between ball and mecanum wheel actuator inevitably occurs along diagonal axis due to its instantaneous strong torque. In order to reduce and saturate slip, exact distance calculation scheme especially for rotational movement is essential. So this research solved Euler-Lagrange dynamics for proposed two axis ball robot based on practical mechanical modeling. Robust balance control was carried out by PID controller according to the pitch and roll angles of ball robot by using sensor fusion between AHRS and wheel encoder. Proposed PID controller enhances stability by reducing steady state error and settling time. Proposed slip control algorithm for omni-directional ball robot has been demonstrated by experiments for balance control and arbitrary driving control.

• 한국생산제조학회지
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• 제23권4호
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• pp.374-379
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• 2014

Mobile robots with omni-directional wheels can generate instant omni-directional motion without requiring extra space to change the direction of the body. Therefore, they are capable of moving in an arbitrary direction under any orientation even in narrow aisles or tight areas. In this research, an omni-directional mobile robot based on Mecanum wheels was developed to achieve omni-directionality. A CompactRIO embedded real-time controller and C series motion and I/O modules were employed in the control system design. Ultrasonic sensors installed on the front and lateral sides were utilized to measure the distance between the mobile robot and the side wall of a workspace. Through intensive experiments, a performance evaluation of the mobile robot was conducted to confirm its feasibility for industrial purposes. Mobility, omni-directionality, climbing capacity, and tracking performance of a squared trajectory were selected as performance indices to assess the omni-directional mobile robot.

• 로봇학회논문지
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• 제5권4호
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• pp.326-331
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• 2010

Marionette controlling robot has a problem that generates interference in rotation and intersection, therefore, the research on the independent shifter to move freely on the stage is required. Connecting omni-directional mobile robot with marionette controlling robot can solve this problem. Omni-directional mobile robot makes itself rotate and translate in 2D plane freely. Magnetic device is used to connect the moving part with the control part of the robot to minimize the intereference generated by the movement of robot. When robot moves, it can move to all directions with the suitalbe setting of banlance power. The moment of inertia is minimized by dividing the robot to the upper and lower parts in the marionette performance stage. Rotation and interference problem of independent omni-wheel Robot can be solved by using the permanent magnet. The efficiency and safety of the marionette controlling robot is proved by the experiment.