Date of Award

2013

Access Type

Dissertation - Open Access

Degree Name

Doctor of Philosophy in Engineering Physics

Department

Physical Sciences

Committee Chair

Sergey V. Drakunov

First Committee Member

Yechiel J. Crispin

Second Committee Member

William MacKunis

Third Committee Member

Gregory S. Spradlin

Abstract

The motion of rigid bodies includes three degrees of freedom (DOF) for rotation, generally referred to as roll, pitch and yaw, and 3 DOF for translation, generally described as motion along the x, y and z axis, for a total of 6 DOF. Many complex mechanical systems exhibit this type of motion, with constraints, such as complex humanoid robotic systems, multiple ground vehicles, unmanned aerial vehicles (UAVs), multiple spacecraft vehicles, and even quantum mechanical systems. These motions historically have been analyzed independently, with separate control algorithms being developed for rotation and translation. The goal of this research is to study the full 6 DOF of rigid body motion together, developing control algorithms that will affect both rotation and translation simultaneously. This will prove especially beneficial in complex systems in the aerospace and robotics area where translational motion and rotational motion are highly coupled, such as when spacecraft have body fixed thrusters.

A novel mathematical system known as dual quaternions provide an efficient method for mathematically modeling rigid body transformations, expressing both rotation and translation. Dual quaternions can be viewed as a representation of the special Euclidean group SE (3). An eight dimensional representation of screw theory (combining dual numbers with traditional quaternions), dual quaternions allow for the development of control techniques for 6 DOF motion simultaneously. In this work variable structure nonlinear control methods are developed for dual quaternion systems. These techniques include use of sliding mode control. In particular, sliding mode methods are developed for use in dual quaternion systems with unknown control direction. This method, referred to as self-reconfigurable control, is based on the creation of multiple equilibrium surfaces for the system in the extended state space. Also in this work, the control problem for a class of driftless nonlinear systems is addressed via coordinate transformation. It is shown that driftless nonlinear systems that do not meet Brockett's conditions for coordinate transformation can be augmented such that they can be transformed into the Brockett's canonical form, which is nonholonomic. It is also shown that the kinematics for quaternion systems can be represented by a nonholonomic integrator. Then, a discontinuous controller designed for nonholonomic systems is applied. Examples of various applications for dual quaternion systems are given including spacecraft attitude and position control and robotics.

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