• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권2호
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• pp.154-161
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• 2012

This article presents experimental studies of fuzzy logic application to control a two-wheel mobile robot(TWMR) system. The TWMR system is composed of two systems, an inverted pendulum system and a mobile robot system. Although linear controllers can stabilize the TWMR, fuzzy controllers are expected to have robustness to uncertainties so that the resulting performances are expected to be better. Nominal fuzzy rules are used to control balance and position of TWMR. Fuzzy logic is embedded on a DSP chip to control the TWMR. Balancing performances of the PID controller and the fuzzy controller under disturbances are compared through extensive experimental studies.

• 제어로봇시스템학회논문지
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• 제16권11호
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• pp.1060-1067
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• 2010

In this paper, we present a new type of spherical robot having two arms. This robot, called KisBot, mechanically consists of three parts, a wheel-shaped body and two rotating semi-spheres. In side of each semi-sphere, there exists an arm which is designed based on slider-crank mechanism for space efficiency. KisBot has hybrid types of driving mode: rolling and wheeling. In the rolling mode, the robot folds its arms through inside of itself and uses them as pendulum, then the robot works like a pendulum-driven robot. In the wheeling mode, two arms are extended from inside of the robot and are contacted to the ground, then the robot works like a one-wheel car. The Robot arms can be used as a brake during rolling mode and add friction to the robot for climbing a slope during wheeling mode. We developed a remote controlled type robot for experiment. It contains two DC motors which are located in the center of each semi-sphere for main propulsion, two RC motors for each arm operation, speed controllers for each semi-sphere, batteries for main power source, and other mechanical components. Experiments for the rolling and wheeling mode verify the hybrid driving ability and efficiency of the our proposed spherical robot.

• 제어로봇시스템학회논문지
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• 제19권3호
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• pp.233-239
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• 2013

This paper presents the analysis and control of the position of the COG (Center of Gravity) for a two-wheel balancing robot. The two-wheel balancing robot is required to maintain balance by driving two wheels only. Since the robot is not exactly symmetrical and its dynamics is changing with respect to moving parts, robust balancing control is difficult. Balancing performance becomes difficult when two arms hold a heavy object since the center of gravity is shifted out of the wheel axis. Novel design of a sliding waist mechanism allows the robot to react against the shift of the COG by moving the whole upper body to compensate for the imbalance of the mass as a counter balancer. To relocate the COG position accurately, the COG is analyzed by force data measured from two force sensors. Then the sliding COG mechanism is utilized to control the sliding waist position. Experimental studies are conducted to confirm the proposed design and method.

• 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.

• 로봇학회논문지
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• 제3권4호
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• pp.338-344
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• 2008

Most omni-directional mobile robots have to change their trajectory for avoiding obstacles regardless of the size of the obstacles. However, an omni-directional mobile robot having kinematic redundancy can maintain the trajectory while the robot avoids small obstacles. This works deals with the kinematic modeling and motion planning of an omni-directional mobile robot with kinematic redundancy. This robot consists of three wheel mechanisms. Each wheel mechanism is modeled as having four joints, while only three joints are necessary for creating the omni-directional motion. Thus, each chain has one kinematic redundancy. Two types of wheel mechanisms are compared and its kinematic modeling is introduced. Finally, several motion planning algorithms using the kinematic redundancy are investigated. The usefulness of this robot is shown through experiment.

• 전자공학회논문지SC
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• 제45권1호
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• pp.1-8
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• 2008

자유롭고 빠르게 이동할 수 있도록 도와주는 개인 이동 수단인 two-wheel balancing vehicle은 inverted pendulum 시스템의 원리를 이용한 것으로, 최근 들어 많은 연구가 이루어지고 있고 이를 이용한 제품이 실제 사용되고 있다. 본 논문에서는 일반적인 PID 제어이론을 이용한 two-wheel balancing vehicle에 대한 제어성능을 개선시키는 새로운 제어방식을 제안한다. 제안한 방식은 퍼지 PD+I 제어방식으로 향상된 PID 제어의 일종으로 2개의 입력과 1개의 출력을 가진 퍼지시스템에 적분 신호를 더함으로써 출력신호를 만든다. 퍼지시스템의 비선형성은 시간공정에서 비례신호와 미분신호의 가중치를 변화함으로써 최적의 출력제어신호를 만들어낸다. 제안한 퍼지 PD+I 제어방식의 유용성을 알아보기 위해 two-wheel balancing mobile robot에 대해 시뮬레이션과 실험의 결과를 통해, 제안한 퍼지 PD+I 제어방식이 일반적인 PID 방식보다 우수한 성능을 가지고 있음을 알 수가 있다.

• 제어로봇시스템학회논문지
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• 제22권4호
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• pp.281-287
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• 2016

In this paper, we propose a novel compact surveillance throwing robot which has an omnidirectional shock absorption mechanism and an active control part of wheel treads to stabilize the dynamic posture of a miniature sphere type throwing robot. This throwing robot, which weighs 1.14kg and is 110mm in height, is designed in a spherical shape to be easily grabbed for throwing. Also, the omnidirectional shock absorbing aspect is designed using several leaf springs connected with inner and outer wheels. The wheel treads control part consists of a link mechanism. Through the field experiments, this robot is validated to withstand higher than 17Ns of omnidirectional impulse and increase the stabilized max speed three times from 11 rad/s to 33rad/s by increasing wheel treads.

• 제어로봇시스템학회논문지
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• 제18권3호
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• pp.275-284
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• 2012

This paper proposes an attitude and direction control of a single wheel balanced robot. A unicycle robot is controlled by two independent control laws: the mobile inverted pendulum control method for pitch axis and the reaction wheel pendulum control method for roll axis. It is assumed that both roll dynamics and pitch dynamics are decoupled. Therefore the roll and pitch dynamics are obtained independently considering the interaction as disturbances to each other. Each control law is implemented by a controller separately. The unicycle robot has two DC motors to drive the disk for roll and to drive the wheel for pitch. Since there is no force to change the yaw direction, the present paper proposes a method for changing the yaw direction. The angle data are obtained by a fusion of a gyro sensor and an accelerometer. Experimental results show the performance of the controller and verify the effectiveness of the proposed control algorithm.

• 제어로봇시스템학회논문지
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• 제8권6호
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• pp.498-505
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• 2002

Reducing odometer errors caused by kinematic imperfections in wheeled mobile robots is imestigated. Wheel diameters and wheelbase are corrected by using encoders without landmarks. A new velocity trajectory is proposed that compensates for an orientation error due to acceleration- resolution constraints on motor controllers. Based on this velocity trajectory, the wheel velocity of one out of two driven wheels may be changed by the traveled distance of the mobile robot. It is shown that a wheeled mobile robot can't move along a straight line exactly, even if kinematic correction are achieved perfectly, and this phenomenon is attributable to acceleration-resolution constraints on motor controllers. We experiment on a wheeled mobile robot with 2 d.o.f. are used in the experiment to verify the proposed scheme.

• 한국정밀공학회지
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• 제28권10호
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• pp.1181-1188
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• 2011

A control system for stabilizing a small robot or inverted pendulum using twisted gyro wheel is proposed. Conventional stabilizer using inertial wheel employs action-reaction force/torque to control a pendulum, which can generate relatively small torque and short period of output. In this paper, a novel actuation method using twisted gyro torque in 3-dimentional space was proposed to stabilizing a pendulum by twisting the assembly including a rotating gyro wheel. In addition, two special control functions for this type of twisted gyro wheel were designed. One is the function of self-adjusting the mass center of the robot and the other is the torque reloading configuration for continuous torque generation. The proposed system was verified by experimental result and simulation. The designed twisted gyro wheel control system can be easily packed in a small size module and installed in a humanoid robot or inverted pendulum type mechanism.