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According to W. Edwards Deming, American companies require nothing less than a transformation of management style and of governmental relations with industry. In Out of the Crisis, originally published in 1982, Deming offers a theory of management based on his famous 14 Points for Management. Management's failure to plan for the future, he claims, brings about loss of market, which brings about loss of jobs. Management must be judged not only by the quarterly dividend, but by innovative plans to stay in business, protect investment, ensure future dividends, and provide more jobs through improved product and service. In simple, direct language, he explains the principles of management transformation and how to apply them.

Out of the Crisis

A central problem in motor control is understanding how the many biomechanical degrees of freedom are coordinated to achieve a common goal. An especially puzzling aspect of coordination is that behavioral goals are achieved reliably and repeatedly with movements rarely reproducible in their detail. Existing theoretical frameworks emphasize either goal achievement or the richness of motor variability, but fail to reconcile the two. Here we propose an alternative theory based on stochastic optimal feedback control. We show that the optimal strategy in the face of uncertainty is to allow variability in redundant (task-irrelevant) dimensions. This strategy does not enforce a desired trajectory, but uses feedback more intelligently, correcting only those deviations that interfere with task goals. From this framework, task-constrained variability, goal-directed corrections, motor synergies, controlled parameters, simplifying rules and discrete coordination modes emerge naturally. We present experimental results from a range of motor tasks to support this theory.

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Optimal feedback control as a theory of motor coordination.

Forward models for physiological motor control

The sensorimotor system is a product of evolution, development, learning and adaptation-which work on different time scales to improve behavioral performance. Consequently, many theories of motor function are based on 'optimal performance': they quantify task goals as cost functions, and apply the sophisticated tools of optimal control theory to obtain detailed behavioral predictions. The resulting models, although not without limitations, have explained more empirical phenomena than any other class. Traditional emphasis has been on optimizing desired movement trajectories while ignoring sensory feedback. Recent work has redefined optimality in terms of feedback control laws, and focused on the mechanisms that generate behavior online. This approach has allowed researchers to fit previously unrelated concepts and observations into what may become a unified theoretical framework for interpreting motor function. At the heart of the framework is the relationship between high-level goals, and the real-time sensorimotor control strategies most suitable for accomplishing those goals.

/pdf/optimality-principles-in-sensorimotor-control-5bziqn38js.pdf

Optimality principles in sensorimotor control

This study examined the variability in movement end points in a task in which human subjects reached to targets in different locations on a horizontal surface. The primary purpose was to determine whether patterns in the variable errors would reveal the nature and origin of the coordinate system in which the movements were planned. Six subjects moved a hand-held cursor on a digitizing tablet. Target and cursor positions were displayed on a computer screen, and vision of the hand and arm was blocked. The screen cursor was blanked during movement to prevent visual corrections. The paths of the movements were straight and thus directions were largely specified at the onset of movement. The velocity profiles were bell-shaped, and peak velocities and accelerations were scaled to target distance, implying that movement extent was also programmed in advance of the movement. The spatial distributions of movement end points were elliptical in shape. The major axes of these ellipses were systematically oriented in the direction of hand movement with respect to its initial position. This was true for both fast and slow movements, as well as for pointing movements involving rotations of the wrist joint. Using principal components analysis to compute the axes of these ellipses, we found that the eccentricity of the elliptical dispersions was uniformly greater for small than for large movements: variability along the axis of movement, representing extent variability, increased markedly but nonlinearly with distance. Variability perpendicular to the direction of movement, which results from directional errors, was generally smaller than extent variability, but it increased in proportion to the extent of the movement. Therefore, directional variability, in angular terms, was constant and independent of distance. Because the patterns of variability were similar for both slow and fast movements, as well as for movements involving different joints, we conclude that they result largely from errors in the planning process. We also argue that they cannot be simply explained as consequences of the inertial properties of the limb. Rather they provide evidence for an organizing mechanism that moves the limb along a straight path. We further conclude that reaching movements are planned in a hand-centered coordinate system, with direction and extent of hand movement as the planned parameters. Since the factors which influence directional variability are independent of those that influence extent errors, we propose that these two variables can be separately specified by the brain.

Accuracy of planar reaching movements. I: Independence of direction and extent variability

This study examines the source of direction-dependent errors in movement extent made by human subjects in a reaching task As in the preceding study, subjects were to move a cursor on a digitizing tablet to targets displayed on a computer monitor Movements were made without concurrent visual feedback of cursor position, but movement paths were displayed on the monitor after the completion of each movement We first examined horizontal hand movements made at waist level with the upper arm in a vertical orientation Targets were located at five distances and two directions (30 degrees and 150 degrees) from one of two initial positions Trajectory shapes were stereotyped, and movements to more distant targets had larger accelerations and velocities Comparison of movements in the two directions showed that in the 30 degrees direction responses were hypermetric, accelerations and velocities were larger, and movement times were shorter Since movements in the 30 degrees direction required less motion of the upper arm than movements in the 150 degrees direction, we hypothesized that the differences in accuracy and acceleration reflected a failure to take into account the difference in total limb inertia in the two directions To test this hypothesis we simulated the initial accelerations of a two-segment limb moving in the horizontal plane with the hand at shoulder level when a constant force was applied at the hand in each of 24 directions We compared these simulated accelerations to ones produced by our subjects with their arms in the same position when they aimed movements to targets in the 24 directions and at equal distances from an initial position The magnitudes of both simulated and actual accelerations were greatest in the two directions perpendicular to the forearm, where inertial resistance is least, and lowest for movements directed along the axis of the forearm In all subjects, the directional variation in peak acceleration was similar to that predicted by the model and shifted in the same way when the initial position of the hand was displaced The pattern of direction-dependent variations in initial acceleration did not depend on the speed of movement It was also unchanged when subjects aimed their movements toward targets presented within the workspace on the tablet instead of on the computer monitor These findings indicate that, in programming the magnitude of the initial force that will accelerate the hand, subjects do not fully compensate for direction dependent differences in inertial resistance(ABSTRACT TRUNCATED AT 400 WORDS)

Accuracy of planar reaching movements. II. Systematic extent errors resulting from inertial anisotropy.

1. This paper introduces a series of studies in which we analyze the impairments in a planar reaching task in human patients with severe proprioceptive deficits resulting from large-fiber sensory n...

Impairments of reaching movements in patients without proprioception. I. Spatial errors.

In "The New Science of Strong Materials" the author made plain the secrets of materials science. In this volume he explains the importance and properties of different structures.

Structures: Or Why Things Don't Fall Down

https://www.archives-pmr.org/article/S0003-9993(08)00235-9/pdf

James Gordon

Papers

Accuracy of planar reaching movements. I: Independence of direction and extent variability

Accuracy of planar reaching movements. II. Systematic extent errors resulting from inertial anisotropy.

Impairments of reaching movements in patients without proprioception. I. Spatial errors.

Structures: Or Why Things Don't Fall Down

The Effect of Exercise Training in Improving Motor Performance and Corticomotor Excitability in People With Early Parkinson's Disease