• 제어로봇시스템학회논문지
• /
• 제14권9호
• /
• pp.881-885
• /
• 2008

To calculate the attitude in ARS(Attitude Reference System) using 3 gyros and 3 accelerometers, gyro drift must be compensated with accelerometer to avoid divergence of attitude error. Kalman filter is most popular method to integrate those two sensor outputs. In this paper, new Kalman filtering method is proposed for roll and pitch attitude estimation. New states are defined to make linear equation and algorithm for changing Kalman filter parameters is proposed to ignore disturbances of acceleration. This algorithm can be easily applied to low cost ARS.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.1429-1432
• /
• 2005

This work is towards the development of a low-cost, small-sized inertial navigation system(INS) which consists of 3 accelerometers, 3 semiconductor gyros and a magnetic compass sensor. This paper explains in detail the structure of the developed system and proposes a 3 dimensional attitude estimation algorithm with Indirect Kalman Filter. The experiments are performed with the developed system attached to a 6 DOF robot for showing the effectiveness of the algorithm.

• 제어로봇시스템학회논문지
• /
• 제16권11호
• /
• pp.1104-1109
• /
• 2010

This paper deals with the attitude control of an underactuated spacecraft that has fewer than three actuators. Even though such spacecrafts are known as uncontrollable, restricted missions are possible with controlling two-axis attitude angles. A variable speed control moment gyroscope is considered as an actuator. It is a kind of momentum exchange device and it shows highly nonlinear dynamical properties. Speed commands are generated by kinematic equations represented by Euler angles. A control law, that is designed to make a spacecraft follow the speed commands, is derived by the backstepping method. Angular speeds are estimated from the attitude measurements. Several estimation methods have been compared.

• 한국항공운항학회지
• /
• 제19권4호
• /
• pp.44-50
• /
• 2011

This paper presents the algorithm for attitude determination of an aircraft using binary image. An image feature vector, which is invariant to translation, scale and rotation, is constructed to capture the functional relations between the feature vector and the corresponding aircraft attitude. An iterated least squares method is suggested for estimating the attitude of given aircraft using the constructed feature vector library. Simulation results show that the proposed algorithm yields good estimates of aircraft attitude in most viewing range, although a relatively large error occurs in some limited viewing direction.

• International Journal of Aeronautical and Space Sciences
• /
• 제14권1호
• /
• pp.91-98
• /
• 2013

The rigorous requirements of modern spacecraft missions necessitate a precise attitude determination strategy. This paper mainly researches that, based on three space-borne attitude sensors: 3-axis rate gyros, 3-antenna GPS receiver and star-sensor. To obtain global attitude estimation after an information fusion process, a feedback-involved Federated Kalman Filter (FKF), consisting of two subsystem Kalman filters (Gyros/GPS and Gyros/Star-sensor), is established. In these filters, the state equation is implemented according to the spacecraft's kinematic attitude model, while the residual error models of GPS and star-sensor observed attitude are utilized, to establish two observation equations, respectively. Taking the sensors' different update rates into account, these two subsystem filters are conducted under a variable step size state prediction method. To improve the fault tolerant capacity of the attitude determination system, this paper designs malfunction warning factors, based on the principle of ${\chi}^2$ residual verification. Mathematical simulation indicates that the information fusion strategy overwhelms the disadvantages of each sensor, acquiring global attitude estimation with precision at a 2-arcsecs level. Although a subsystem encounters malfunction, FKF still reaches precise and stable accuracy. In this process, malfunction warning factors advice malfunctions correctly and effectively.

• 한국항공우주학회지
• /
• 제41권7호
• /
• pp.532-538
• /
• 2013

본 논문은 편대비헹에서 영상만을 이용하여 선도기의 자세를 예측 하는 알고리즘 개발에 대해 논하고 있다. X-PLANE 시뮬레이터를 이용하여 획득한 영상에 SURF(Speed Up Robust Features)알고리즘을 이용하여 특징점을 추출 하였다. 그리고 자세예측 방법은 POSIT(Pose from Orthography and Scaling with Iteration) 알고리즘을 사용하였다. 결론적으로 우리는 영상만을 이용한 자세추정법이 $1.1{\sim}1.76^{\circ}$의 작은 추정오차 결과를 나타냄을 확인할 수 있었다.

• 제어로봇시스템학회논문지
• /
• 제14권2호
• /
• pp.133-140
• /
• 2008

In this paper, a small and effective attitude estimation system for a humanoid robot was developed. Four small inertial sensors were packed and used for inertial measurements(3D accelerometer and three 1D gyroscopes.) An effective 3D pose estimation algorithm for low cost DSP using an extended Kalman filter was developed and evaluated. The 3D pose estimation algorithm has a very simple structure composed by 3 modules of a linear acceleration estimator, an external acceleration detector and an pseudo-accelerometer output estimator. The algorithm also has an effective switching structure based on probability and simple feedback loop for the extended Kalman filter. A special test equipment using linear motor for the testing of the 3D pose sensor was developed and the experimental results showed its very fast convergence to real values and effective responses. Popular DSP of TMS320F2812 was used to calculate robot's 3D attitude and translated acceleration, and the whole system were packed in a small size for humanoids robots. The output of the 3D sensors(pitch, roll, 3D linear acceleration, and 3D angular rate) can be transmitted to a humanoid robot at 200Hz frequency.

• International Journal of Control, Automation, and Systems
• /
• 제5권1호
• /
• pp.15-23
• /
• 2007

In surveillance, monitoring, and target tracking operations, high-resolution images should be obtained even if the target is in a far distance. Frequent movements of vehicles such as boats degrade the image quality of onboard camera systems. Therefore, stabilizer mechanisms are required to stabilize the line of sight of boatboard camera systems against boat movements. This paper addresses design and implementation of a strapdown boatboard camera stabilizer. A two degree of freedom(DOF)(pan/tilt) robot performs the stabilization task. The main problem is divided into two subproblems dealing with attitude estimation and attitude control. It is assumed that exact estimate of the boat movement is available from an attitude estimation system. Estimates obtained in this way are carefully transformed to robot coordinate frame to provide desired trajectories, which should be tracked by the robot to compensate for the boat movements. Such a practical robotic system includes actuators with fast dynamics(electrical dynamics) and has more degrees of freedom than control inputs. Backstepping method is employed to deal with this problem by extending the control effectiveness.

• 한국항공우주학회지
• /
• 제38권4호
• /
• pp.342-351
• /
• 2010

UAV는 임무 수행을 위한 INS 장비와 광학 장비를 갖추고 있다. 이 논문에서는 UAV를 위한 알고리즘으로 칼만 필터와 광류를 이용하는 영상기반 자세추정 알고리즘을 제안한다. 광류는 UAV에 장착된 카메라의 영상으로부터 획득하며 UAV의 자세는 광류를 통해 측정된다. 이 논문에서 UAV 자세의 추정과 낮은 신뢰성을 보완하기위해 칼만 필터를 사용한다. 그리고 실험을 통해 알고리즘을 검증하였다. Rate table과 실제 비행영상을 이용하여 실험 하였으며, 본 논문에서 UAV의 자세 추정 알고리즘 검증 결과를 보였다. Rate table 실험에서 오차는 2도 이내였으며, AHRS를 통해 측정한 결과와 비슷한 경향을 보인다. 그러나 실제 비행 영상 실험에서 최대 Yaw 오차는 21도였으며, 최대 Pitch 오차는 7.8도로 나타났다.

• 융합정보논문지
• /
• 제8권6호
• /
• pp.135-142
• /
• 2018

최근에 정밀 추적이나 타격 등의 군사 목적으로 UAV를 활용하는 연구가 매우 활발하게 진행되고 있다. 앞서가는 비행체를 추적하기 위해 후방에서 촬영한 영상을 활용하여 롤, 피치, 요와 같은 그 비행체의 자세 정보를 추정하는 기존의 연구가 진행되었다. 본 연구에서는 기존의 영상처리기법을 이용한 연구에 칼만 필터를 적용함으로써 자세 정보를 더욱 정밀하게 추정하는 방법을 제시한다. 영상처리를 사용해서 추정한 비행 자세 데이터에 칼만 필터를 적용함으로써 기존의 방식에서 발생했던 자세 각도의 추정오차 범위를 크게 줄일 수 있었다. 시뮬레이션 실험을 통해서, 칼만 필터를 적용할 경우 비행체의 자세 정보를 더욱 정확하게 추정할 수 있음을 확인할 수 있었다.