He-Sheng Wang

Estimation of relative orientation using dual quaternion

In this thesis, we use dual quaternion to solve relative orientation, which replaces the traditional way of coplanarity condition and least square solution. Through proposing Linearized Iteration Method, we use only one camera to deal with this problem. Through use of dual quaternion, we find the relative orientation by comparing the projection of lines respect to 2-D Camera systems.

The positive real control problem and the generalized algebraic Riccati equation for descriptor systems

Abstract In this paper, some useful properties of generalized algebraic Riccati equations and generalized positive real lemma for descriptor systems are given. Based on these results, the main purpose of this paper is to investigate the positive real (PR) control problem for descriptor systems. Necessary and sufficient conditions are derived for the solution to this problem expressed in terms of two generalized algebraic Riccati equations which may be considered to be generalizations of the Riccati equations obtained by Sun et al. (1994). When these conditions hold, state space formulae for all controllers solving the problem are also given.

Bounded real lemma and H/sub /spl infin// control for descriptor systems

The purpose of this paper is to give a necessary and sufficient condition under which for a given plant of descriptor system model there exists a normal, internally stabilizing controller that has an upper limit on its order and that satisfies a closed-loop H/sub /spl infin// norm bound. The approach used in this paper is based on a generalized version of bounded real lemma, thus the proofs are simple.

A closed-form algorithm for eliminating user position biases caused by satellite constellation changes

In GPS positioning, the user position is derived by the pseudo-range measurements and the user-satellite geometric matrix. When the satellite constellation changed, either gaining or losing satellites, it may cause the user position biases. The instantaneous biases in position solution are not desirable in some applications. An algorithm called position bias filter has been proposed to solve the problem. Also, a modified algorithm is designed to reduce the computation burden of original algorithm by a recursive method. In this paper, we propose a closed-form algorithm for eliminating the user position biases. The algorithm remains the low computation in a few satellites change (less than four) of satellite constellation without recursive calculation.

Derivation of the optimal guidance law for space vehicle based on a DAE approach

In the simulation of space vehicles, we often encounter the trajectory prescribed path control (TPPC) problems. That is, we usually append a set of path constraints to the equations of motion for describing the shape of the trajectory. To describe the TPPC problem, the concept of the differential-algebraic equation (DAE) system is usually adopted. In this paper, the optimal guidance law for aircraft dynamics is derived based on a DAE approach. We will reformulate the problem as a Hamiltonian DAE system. After establishing the system of aircraft dynamics, we can derive the optimal guidance law of the system by numerical method. The numerical method is mainly based on the backward differential formulas (BDF).

Mixed H 2 /H8control problem for descriptor systems

Abstract In this paper, a mixed H 2 /H8 control problem for descriptor systems is solved via the Nash game approach. Both state feedback and static output feedback cases are examined. The control strategies are characterized by two cross‐coupled generalized algebraic Riccati equations, and thus can be solved using some numerical procedures. The results obtained in this paper generalize some recent results in the literature.

/spl Hscr//sub /spl infin// control for nonlinear differential-algebraic equations

In this paper, we study the /spl Hscr//sub /spl infin// control problem for nonlinear differential-algebraic equations (DAE). Necessary and sufficient conditions are derived for the existence of a controller solving the problem. We first give various sufficient conditions for the solvability of /spl Hscr//sub /spl infin// control problem for DAE. Both state feedback and output feedback cases are considered. Then, necessary conditions for the output feedback control problem to be solvable are obtained in terms of two Hamilton-Jacobi inequalities plus a weak coupling condition. Moreover, a parameterization of a family of output feedback controllers solving the problem is also provided.