The purpose of this thesis is to develop methods to generate minimum-energy consumption trajectories for a point-to-point motion under pre-defined kinematic and dynamic constraints for robotic manipulators. With respect to other trajectory optimization methods, the work presented in this thesis provides two new methods to the scientific literature. The proposed methods improve the handling of the constraints in trajectory optimization methods as well as reducing the computational complexity of redundant/hyper-redundant manipulator systems.

<p>A kinematically redundant four degrees of freedommanipulator arm, a knuckle boom, is studied. Three joints arerevolute and one linear. Since only three degrees of freedomare needed for positioning, we have one redundant degree offreedom. Three different kinematic control strategies arestudied. One is based on the maximization of velocity (localoptimisation). This strategy is non-repeatable and cansometimes lead to kinematically unfavourable positions. In thesecond strategy, which is based on the maximization of staticlifting capacity (local optimisation), one of the degrees offreedom (the linear joint) is made a function of the toolcentre point position. The third strategy, which is based ondynamic programming (global optimization), calculates theshortest time that is possible for the tool centre point to gofrom one point to another point in the working area. The threestrategies are compared in a simulation study. The simulationsshow the necessary speed requirements for all joints whenperforming straight paths in the manipulator work area. Thesimulations also show the difference in time consumptionsbetween the three control algorithms and also what happens whenthe joints reach their maximum velocity limits.</p><p><strong>Keywords</strong>Manipulator, Kinematic Control, RedundantLanguage</p>

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The eigenstructure assignment scheme for robust multivariable feedback control is extended to redundantly actuated dynamical systems. It is shown that an orthonormal set of close loop eigenvectors is always exactly assignable in the case of redundant actuation proving the inherent robustness in the control design methodology. A choice of close loop eigenvector set to minimize the feedback gain matrix is suggested. Partial Eigenstructure Assignment methodology is proposed for second order mechanical systems. A methodology for coordinated actuation of redundant actuator sets by a trained weighted minimum norm solution is presented. To apply the methodology to hyper-redundant actuator arrays, for application to smart actuator arrays, a novel adaptive discretization algorithm is proposed. The adaptive aggregation strategy, based on the physics of the system, introduces nodes, to optimize a performance index of the overall plant model. The dimensionality of the inputs thus reduces to a finite number, making it a candidate plant for control by the robust redundant control scheme. The adaptive aggregation together with robust redundant control methodology is demonstrated on a finite element model of a novel morphing wing. This schema unifies the traditionally disparate methods of modeling and controller design.

A kinematically redundant four degrees of freedommanipulator arm, a knuckle boom, is studied. Three joints arerevolute and one linear. Since only three degrees of freedomare needed for positioning, we have one redundant degree offreedom. Three different kinematic control strategies arestudied. One is based on the maximization of velocity (localoptimisation). This strategy is non-repeatable and cansometimes lead to kinematically unfavourable positions. In thesecond strategy, which is based on the maximization of staticlifting capacity (local optimisation), one of the degrees offreedom (the linear joint) is made a function of the toolcentre point position. The third strategy, which is based ondynamic programming (global optimization), calculates theshortest time that is possible for the tool centre point to gofrom one point to another point in the working area. The threestrategies are compared in a simulation study. The simulationsshow the necessary speed requirements for all joints whenperforming straight paths in the manipulator work area. Thesimulations also show the difference in time consumptionsbetween the three control algorithms and also what happens whenthe joints reach their maximum velocity limits. KeywordsManipulator, Kinematic Control, RedundantLanguage

We have derived a new performance measure, product of minors of the Jacobian matrix, that tells how far kinematically redundant manipulators are from singularity. It was demonstrated that previously used performance measures, namely condition number and manipulability measure allowed to change configurations, caused repeatability problems and discontinuity effects. The new measure, on the other hand, assures that the arm solution remains in the same configuration, thus effectively preventing these problems.

Methods for resolving kinematic redundancies of manipulators by the effect on joint torque are examined. When the generalized inverse is formulated in terms of accelerations and incorporated into the dynamics, the effect of redundancy resolution on joint torque can be directly reflected. One method chooses the joint acceleration null-space vector to minimize joint torque in a least squares sense; when the least squares is weighted by allowable torque range, the joint torques tend to be kept within their limits. Contrasting methods employing only the pseudoinverse with and without weighting by the inertia matrix are presented. The results show an unexpected stability problem during long trajectories for the null-space methods and for the inertia-weighted pseudoinverse method, but rarely for the unweighted pseudoinverse method. Evidently a whiplash action develops over time that thrusts the endpoint off the intended path, and extremely high torques are required to overcome these natural movement dynamics.

In this report, a method for exploiting the redundancy of a hand-arm mechanical system for manipulation tasks is illustrated. The basic idea is to try to exploit the different intrinsic capabilities of the arm and hand subsystems. The Jacobian transpose technique is at the core of the method: different behaviors of the two subsystems are obtained by means of constraints in Null(J) generated by non-orthogonal projectors. Comments about the computation of the constraints are reported in the memo, as well as a description of some preliminary experiments on a robotic system at the A.I. Lab., M.I.T.

Inertial measurement units (IMUs) are used in a wide range of applications to estimate position, velocity, and attitude of vehicles. The high cost of tactical grade IMUs makes the low-cost microelectromechanical systems (MEMS) based IMUs appealing. These types of IMUs are less accurate, so to counteract this effect, multiple and different configurations should be used. The work presented here provides efficient and low cost solutions using different configurations of redundant (multiple) MEMS-IMU swarms, which increase the level of accuracy to potentially the order of that of a tactical IMU. Several configurations are presented and compared through different methods. / text

Abstract not available: / Thesis (PhD (Systems Engineering))--University of Pretoria, 2007. / Industrial and Systems Engineering / unrestricted