• 제어로봇시스템학회논문지
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• 제14권8호
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• pp.800-808
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• 2008

This paper presents a localization algorithm of the outdoor wheeled mobile robot using the sensor fusion method based on indirect Kalman filter(IKF). The wheeled mobile robot considered with in this paper is approximated to the two wheeled mobile robot. The mobile robot has the IMU and encoder sensor for inertia positioning system and GPS. Because the IMU and encoder sensor have bias errors, divergence of the estimated position from the measured data can occur when the mobile robot moves for a long time. Because of many natural and artificial conditions (i.e. atmosphere or GPS body itself), GPS has the maximum error about $10{\sim}20m$ when the mobile robot moves for a short time. Thus, the fusion algorithm of IMU, encoder sensor and GPS is needed. For the sensor fusion algorithm, we use IKF that estimates the errors of the position of the mobile robot. IKF proposed in this paper can be used other autonomous agents (i.e. UAV, UGV) because IKF in this paper use the position errors of the mobile robot. We can show the stability of the proposed sensor fusion method, using the fact that the covariance of error state of the IKF is bounded. To evaluate the performance of proposed algorithm, simulation and experimental results of IKF for the position(x-axis position, y-axis position, and yaw angle) of the outdoor wheeled mobile robot are presented.

• 제어로봇시스템학회논문지
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• 제12권6호
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• pp.585-593
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• 2006

In this paper, we propose a vision-based simultaneous localization and map-building (SLAM) algorithm. SLAM problem asks the location of mobile robot in the unknown environments. Therefore, this problem is one of the most important processes of mobile robots in the outdoor operation. To solve this problem, Extended Kalman filter (EKF) is widely used. However, this filter requires computational power (${\sim}O(N)$, N is the dimension of state vector). To reduce the computational complexity, we applied compressed extended Kalman filter (CEKF) to stereo image sequence. Moreover, because the mobile robots operate in the outdoor environments, we should estimate full d.o.f.s of mobile robot. To evaluate proposed SLAM algorithm, we performed the outdoor experiments. The experiment was performed by using new wheeled type mobile robot, Robhaz-6W. The performance results of CEKF SLAM are presented.

• 융합신호처리학회논문지
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• 제23권1호
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• pp.21-27
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• 2022

전통적인 자동차 또는 전통적인 두 바퀴형 차동 구동 로봇은 기구적인 구조 때문에 이동 동작에 제한이 있을 수밖에 없다. 자동차 산업에서 내연기관 자동차가 전기차로 빠르게 전환되면서 자동차에 로봇 공학 기술의 적용이 활발하게 모색되고 있다. 로봇 공학 분야에서는 이동체의 자세를 변화시키지 않고도 다양한 방향으로 이동할 수 있는 전방향 이동로봇에 대한 연구가 활발히 진행되어 왔으며 주목할 만한 연구 결과들도 많다. 하지만 대부분의 연구에서 이와 같은 전방향 이동을 구현하기 위해서는 메카넘휠 등과 같은 특수한 형태의 바퀴를 사용해야 하는 제한점이 있다. 우리는 전방향 이동을 위한 특수한 바퀴를 사용하지 않고도 전방향성을 구현할 수 있는 두 바퀴를 갖는 모듈형 로봇을 제안하였었다. 본 논문에서는 모듈형 로봇 2대를 전후로 결합하여 네 바퀴를 갖는 전방향 이동로봇을 새로이 제안하였다. 제안된 로봇은 차동 구동 방식의 이동로봇으로 전자브레이크를 사용하여 바퀴부와 로봇 몸체부를 선택적으로 분리, 결합하는 방식을 사용하며 두 개의 절대치형 엔코더와 네 개의 증분형 엔코더를 사용하여 로봇 바퀴부의 위치와 로봇 바퀴의 속도를 제어한다. 제안된 로봇은 일반적인 타이어 바퀴를 채택하고도 전방향 이동이 가능하다. 로봇을 실 제작하여 대각선 궤적과 정사각형 궤적에서의 주행 실험을 통하여 제안된 로봇의 유용성과 안정성을 검증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.859-864
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• 2003

This paper presents a design for the novel suspension mechanism of a two-wheeled mobile robot having two casters which is used for indoor environment. Although the indoor environment is less rough than the outdoor one, the fixed caster mechanism has some problems such as causing the robot to be immovable because robot's driving wheels do not have contact with the ground. Therefore, we tried installing a spring-damper suspension mechanism to keep driving capability and to remove pitching phenomenon. However, this suspension mechanism also has the problem, which the robot body inclined by disturbances does not return to the initial position. To deal with above problems and to accomplish desired performances, we designed the Multilayered Suspension Mechanism, which has springs and dampers working partially according to the inclined angle and angular velocity of robot body concerned with pitching. To analyze design, the equations of motion describing their dynamics were developed. Using the equations, simulation results show the improved performance. We confirm the usefulness of the Multilayered Suspension Mechanism by construction and test of a actual prototype.

• 제어로봇시스템학회논문지
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• 제20권10호
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• pp.1057-1062
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• 2014

This paper proposes a tip-over detection method for a mobile robot using a support inscribed circle defined as an inscribed circle of a support polygon. A support polygon defined by the contact points between the robot and the terrain is often used to analyze the tip-over. For a robot moving on uneven terrain, if the intersection between the extended line of gravity from the robot's COG and the terrain is inside the support polygon, tip-over will not occur. On the contrary, if the intersection is outside, tip-over will occur. The terrain is detected by using an RGB-D sensor. The terrain is locally modeled as a plane, and thus the normal vector can be obtained at each point on the terrain. The support polygon and the terrain's normal vector are used to detect tip-over. However, tip-over cannot be detected in advance since the support polygon is determined depending on the orientation of the robot. Thus, the support polygon is approximated as its inscribed circle to detect the tip-over regardless of the robot's orientation. To verify the effectiveness of the proposed method, the experiments are carried out using a 4-wheeled robot, ERP-42, with the Xtion RGB-D sensor.