Harry Septanto

A computer cursor controlled by eye movements and voluntary eye winks using a single channel EOG

This paper proposes a computer mouse-like device that is controlled by eye movements and voluntary eye winks using a single channel of EOG. The position of a pair electrode, and time-domain signal analysis are also presented.

The saturated quaternion control law with application for spacecraft formation flying

Rotation matrix parameterization using unit quaternion can represent attitude globally. However, it is not unique and may generates the unwinding phenomenon, besides the issue on the globally asymptotically stability guarantee. This paper proposes a piecewise-continuous scheme of quaternion-based control law that employs a saturation element such that would avoid the unwinding phenomenon. This paper also proposes a consensus control scheme based on the saturated quaternion control law that would show the property of the unwinding phenomenon avoidance and the corresponding graph only need to have a directed spanning tree.

Static anti-windup compensator design of linear Sliding Mode Control for input saturated systems

A feedback control system involving a linear Sliding Mode Controller (SMC) and an input saturated linear plant is considered here. The linear SMC is designed for linear plant without saturation on its input. The resulting feedback system will not necessarily show an intended performance if the control input to the plant is saturated. In addition, a directionality problem for multivariable input systems may occur during the saturation. As a result, transient response performance could be degraded and its control signals may not be stabilizing the feedback system anymore. In this case, a directionality compensator may be designed to overcome the problem while optimizing its performance.

Quaternion-Based attitude control system design of single and cooperative spacecrafts: boundedness of solution approach

It is well known that single equilibrium orientation point in matrix rotation is represented by two equilibrium points in quaternion. This fact would imply nonefficient control effort as well as problem in guaranteeing stability of the two equilibrium points in quaternion. This paper presents a solution to design quaternion-based spacecraft attitude control system whose saturation element is in its control law such that those problems are overcome. The proposed feature of methodology is the consideration on boundedness of solution in the control system design even in the presence of unknown external disturbance. The same methodology is also used to design cooperative spacecrafts attitude control system. Through the proposed method, the most relaxed information-state topology requirement is obtained, that is, the directed graph that contains a directed spanning tree. Some numerical simulations demonstrate effectiveness of the proposed feature of methodology.

The quaternion-based attitude control system with an augmented dynamic

Quaternion-based attitude determination system is considered since it can represent all physical attitudes, but not uniquely. An inappropriate quaternion-based control law would imply to a non-efficient control effort and difficulty in guaranteeing global stability. Many research efforts decide to add complexity in the controller by using jump-discontinuity function and/ or hybrid system. In contrast, this paper proposes a continuous quaternion-based attitude control system with an augmented dynamic that guaranteed to be able to regulate any physical state asymptotically. The effectiveness of the designed system is verified through simulations.

Consensus-based controllers for spacecraft attitude alignment: Simulation results

Spacecraft formation flying control using consensus algorithm means each spacecraft or satellite in a team updates its state based on the information states of its local neighbours in such a way that the final information state of each agent converges to a common value. This paper discusses spacecraft formation within scope of rotational motions i.e. attitude alignment. Two attitude alignment controllers based on consensus algorithm proposed here.Simulations that run as preliminary proof a concept are presented. Simulations run indicate the proposed control laws might solve the attitude alignment problem i.e. consensus is achieved.

Sliding mode control design of linear continuous feedback systems: Two-steps LMI approach

This paper presents a sliding mode controller design of linear continuous systems with the guaranteed asymptotic stability. This controller design is done via two-steps linear matrix inequalities (LMI) approach. A degree of conservativeness is employed to facilitate linear forms of all controller parameters in the LMI formulation. Simulation examples are then given to show the effectiveness of the approach in both regulator and constant input tracking systems.

Indonesia coverage simulation of SAR satellite at near-equatorial orbit

Properties of SAR (Synthetic Aperture Radar) that able to penetrate the cloud and does not depend on the sunlight are a number of advantages when utilized for monitoring tropical region like the IMC (Indonesian Maritime Continent). Moreover, since having areas along equatorial belt, the IMC is at a shortcoming from perspective of highly inclined LEO (Low Earth Orbit) satellite. It would result shorter and infrequent pass times when compared with a near-equatorial LEO satellite whose low inclination. This paper reports on the investigation of a near-equatorial LEO SAR satellite coverage property through simulations. The simulations is run in nine scenarios of orbit parameter that consist of combinations of attitude {500 km, 600 km, 700 km} and inclination {80, 90, 100}. The target area is defined as 50 km x 50 km around Jakarta. Meanwhile, the SAR sensor simulation is run with swath width of 40 km, incidence angle around 250-290 and Stripmap mode. Minimum, Maximum and Mean Access Revisit of the target for each scenarios are resulted.