A simplified yaw-attitude modeling, consistent with Bar-Sever (1996), has been implemented and tested in the NRCan PPP software. For Block IIR GPS satellite it is possible to model yaw-attitude control during eclipsing periods by using the constant hardware yaw rate of 0.20 /s. The Block IIR satellites maintain the nominal yaw attitude even during a shadow crossing (Y. E. Bar-Sever, private com...

A nonlinear adaptive attitude controller is designed in this paper that compensates for dynamic uncertainties in the spacecraft inertia matrix and unknown dynamic and static friction effects in the control moment gyroscope (CMG) gimbals. Attitude control torques are generated by means of a four single gimbal CMG pyramid cluster. The challenges to develop the adaptive controller are that the con...

A control law for an Integrated Power/Attitude Control System (IPACS) for a satellite is presented in this paper. Four non-coplanar momentum wheels in a special configuration, and a set of three thrusters are used to implement the torque inputs. The momentum wheels are used as attitude control actuators, as well as an energy storage mechanism, providing power to the spacecraft. In that respect,...

Small satellites are now capable of performing missions that require accurate attitude determination and control. However, low size, power, and cost requirements limit the types of attitude sensors that can be used on a small craft, making attitude estimation difficult. In particular, star trackers—often the attitude sensors of choice for larger spacecraft—are not practical for small satellites...

High-accuracy pointing capabilities are desired for many three-axis stabilized small satellites. Momentum-based attitude control system actuators, initially developed for larger satellites. are being utilized by small satellites to meetthesc pointing requirements. This paper provides an overview of momentum devices available for small satellite applications and three-axis attitude control syste...

A simple analytical approach for formation-keeping of satellites in the presence of both orbital and attitude requirements is developed. A leader satellite is assumed to be in a J2-perturbed circular reference orbit and each follower satellite is required to stay in its prescribed, desired orbit with respect to the leader satellite, and at the same time, to point to an arbitrarily chosen specif...

Most satellite remote-sensing images are obtained using pushbroom or whiskbroom scans by the coupling of line scans in one dimension and satellite movements in another dimension. Since satellite imagery should be consistent with maps when used as geospatial data, good geometric performance is a challenge for satellite data processing (Lee et al., 2004; Storey et al., 2004). Accurate attitude es...

In this article a new concept of a smart satellite pushbroom imaging system with internal compensation of attitude instability effects is presented. The compensation is performed within the optical path by an active opto-mechatronic stabilization of the focal plane image motion in a closed loop system with visual feedback. The real-time image motion measurement is derived from an auxiliary matr...

This paper investigates a quaternion-based finite time attitude synchronization and stabilization problem for satellite formation flying. Sufficient conditions are presented for finite time boundness and stability of this distributed consensus problem. More specifically, a nonlinear control law based on a finite time control technique is developed such that the attitude of the rigid spacecraft ...