Direct Dynamics recursive methods

The second quantity of interest, the operational space inertia matrix (O.S.I.M.) of a manipulator, is a newer subject of investigation. It was introduced by Khatib [19] as part of the operational space dynamic formulation, in which manipula-Ux control is carried out in end effector variables. The operational space inertia matrix defines the relationship between the gen lized forces and accelerations of the end effectw, effectively reflecting the dynamics of an actuated chain to its tip. This book will demonstrate its value as a tool in the development of Direct Dynamics algorithms for closed-chain configurations. In addition, a number of efficient algorithms, including two linear recursive methods, are derived for its computation. 

Note that the number of operations listed for fl and A in Table 5.2 is less than the total given for these two quantities in the 0 N) Force Propagation Method in Chapter 4. This reduction was achieved through a little insight First we note that the first recursion in the open-chain Direct Dynamics algorithm of... 

The time scales of the structural transitions in (NaCl)35Cl mean that it is impossible to use conventional molecular dynamics to investigate the interfunnel dynamics. Instead we use the master equation method outlined in Section III.D. To reduce the computational expense and numerical difficulties we recursively removed from our sample those minima that are only connected to one other minimum—these dead-end minima do not contribute directly to the probability flow between different regions of the PES. The resulting pruned sample had 1624 minima and 2639 transition states. RRKM theory in the harmonic approximation was used to model the individual rate constants,. ... 

The Newton-Euler method is well suited to a recursive formulation of the kinematic and dynamic equations of motion (Pandy and Berme, 1988) however, its main disadvantage is that all of the intersegmental forces must be eliminated before the governing equations of motion can be formed. In an dtemative formulation of the dynamical equations of motion, Kane s method (Kane and Levinson, 1985), which is also referred to as Lagrange s form of D Alembert s principle, makes explicit use of the fact that constraint forces do not contribute directly to the governing equations of motion. It has been shown that Kane s formulation of the dynamical equations of motion is computationally more efficient than its counterpart, the Newton-Euler method (Kane and Levinson, 1983). 

The constructive method, which is considered as a major breakthrough in control theory, was developed in the last decade. As it stands, the method is intended for feedback control design, and its application to the batch motion case requires the nominal output to be tracked and a suitable definition of finite-time batch motion stability. In a more applied eontext, the inverse optimality idea has been applied to design the nominal motion of homo [11] and copolymer [12] reactor, obtaining results that are similar to the ones drawn from direct optimization [4]. The motion was obtained from the recursive application of the process dynamical inverse [13], and the inverse yielded a nonlinear SF controller [9, 10] that was in turn used to specify a conventional feedforward-feedback industrial control scheme. However, the issues of motion stability and systematized search were not formally addressed. 

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