Showing papers on "Kinematics published in 1982"

Articulated Hands: Force Control and Kinematic Issues

Abstract: Kinematic and control issues are discussed in the context of an articulated, multifinger mechanical hand. Hand designs with particular mobility properties are illustrated, and a definition of accuracy points within manipulator workspace is given. Optimization of tlte physical dimensions of the Stanford-JPL hand is described. Several architectures for position and force control of this multiloop mechanism are described, including a way of dealing with the internal forces inherent in such systems. Preliminary results are shown for the joint torque subsystem used in the hand controller.

Kinematics and Dynamics of Machines

Abstract: Kinematics and dynamics of machines , Kinematics and dynamics of machines , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Aspects of the Kinematic Simulation of Human Movement

Abstract: A kinematic simulation model allows realistic animation of the human body-provided the body is in contact with the ground and input data is accurate.

A Kinematic Analysis of the Baseball Batting Swings Involved in Opposite-Field and Same-Field Hitting

Abstract: The purpose of this study was to examine the mechanics of hitting a baseball to the same and opposite fields. Twenty male subjects were assigned to one of two groups according to their baseball hitting abilities. Each subject performed as many trials as were necessary to successfully hit a pitched ball three times to both the same and opposite fields. Each trial was filmed from above. No significant interactions (p < 0.05) were found between subject groups and field hits with selected temporal and kinematic parameters entered as dependent variables. Significant differences (p < 0.05) were found between body landmark and segment component displacements and velocities at the instant prior to ball contact. The maximum resultant linear and angular speed of the examined body and bat landmarks were found to occur prior to ball contact. Based on the results of the study it was concluded that no interactions exist between hitting ability and hitting technique when hitting to defined field areas and that ...

Errors in the center and angle of rotation of a joint: an experimental study.

Abstract: The error sensitivity in the determination of center and angle of rotations of a body joint performing planar motion is studied. A simple experiment is described to measure the errors in these two kinematic parameters as functions of errors in the input coordinates of markers. The effect of varying the marker locations and the size of motion-step is also studied. The errors in the center of rotation are found to increase dramatically when the two markers subtend angles of about 0 deg or 180 deg and when the motion step size decreases to 1 deg or less. Similar results are found for errors in the angle of rotation which, in addition, increase with decrease in the radius of the markers.

Spatial Kinematic Chains: Analysis ― Synthesis ― Optimization

Abstract: 1 Mathematical Preliminaries.- 1.0 Introduction.- 1.1 Vector space, linear dependence and basis of a vector space.- 1.2 Linear transformation and its matrix representation.- 1.3 Range and null space of a linear transformation.- 1.4 Eigenvalues and eigenvectors of a linear transformation.- 1.5 Change of basis.- 1.6 Diagonalization of matrices.- 1.7 Bilinear forms and sign definition of matrices.- 1.8 Norms, isometries, orthogonal and unitary matrices.- 1.9 Properties of unitary and orthogonal matrices.- 1.10 Stationary points of scalar functions of a vector argument.- 1.11 Linear algebraic systems.- 1.12 Numerical solution of linear algebraic systems.- 1.13 Numerical solution of nonlinear algebraic systems.- References.- 2. Fundamentals of Rigid-Body Three-Dimensional Kinematics.- 2.1 Introduction.- 2.2 Motion of a rigid body.- 2.3 The Theorem of Euler and the revolute matrix.- 2.4 Groups of rotations.- 2.5 Rodrigues' formula and the Cartesian decomposition of the rotation matrix.- 2.6 General motion of a rigid body and Chasles' Theorem.- 2.7 Velocity of a point of a rigid body rotating about a fixed point.- 2.8 Velocity of a moving point referred to a moving observer.- 2.9 General motion of a rigid body.- 2.10 Theorems related to the velocity distribution in a moving rigid body.- 2.11 Acceleration distribution in a rigid body moving about a fixed point.- 2.12 Acceleration distribution in a rigid body under general motion.- 2.13 Acceleration of a moving point referred to a moving observer.- References.- 3. Generalities on Lower-Pair Kinematic Chains.- 3.1 Introduction.- 3.2 Kinematic pairs.- 3.3 Degree of freedom.- 3.4 Classification of lower pairs.- 3.5 Classification of kinematic chains.- 3.6 Linkage problems in the Theory of Machines and Mechanisms.- References.- 4. Analysis of Motions of Kinematic Chains.- 4.1 Introduction.- 4.2 The method of Denavit and Hartenberg.- 4.3 An alternate method of analysis.- 4.4 Applications to open kinematic chains.- References.- 5. Synthesis of Linkages.- 5.1 Introduction.- 5.2 Synthesis for function generation.- 5.3 Mechanism synthesis for rigid-body guidance.- 5.4 A different approach to the synthesis problem for rigid-body guidance.- 5.5 Linkage synthesis for path generation.- 5.6 Epilogue.- References.- 6. An Introduction to the Optimal Synthesis of Linkages.- 6.1 Introduction.- 6.2 The optimisation problem.- 6.3 Overdetermined problems of linkage synthesis.- 6.4 Underdetermined problems of linkage synthesis subject to no inequality constraints.- 6.5 Linkage optimisation subject to inequality constraints. Penalty function methods.- 6.6 Linkage optimisation subject to inequality constraints. Direct methods.- References.- Appendix 1 Algebra of dyadics.- Appendix 2 Derivative of a determinant with respect to a scalar argument.- Appendix 4 Synthesis of plane linkages for rigid-body guidance.

On the Kinematics of the Closed Epicyclic Differential Gears

Abstract: The epicyclic differential gear has been known in modern times since 1575 when it appeared as a mechanism in a clock. Artifacts from an ancient shipwreck prove that it was known to the ancient Greeks at least 100 hundred years before Christ. The methods of kinematic analysis by either the relative angular velocity method or the instant center and linear velocity method, as given in the literature, are oriented toward specific solutions rather than general ones; they do not readily allow for parametric trend studies and they require a degree of imagination and intuition which may well be beyond the capabilities of those who are not practitioners of the art. The discussed methodology defines simple and compound epicyclic gears in terms of the overall ratio of a geometrically similar planetary gear. The kinematic analysis is derived in general terms for both the simple and compound epicyclic gear. It is shown that location of the point of zero tangential velocity of the velocity triangle relative to the system datum governs the characteristics of the gearset and whether it will perform as a differential gearset, or as a solar, star, or planetary gear. Simple mathematical relationships are given which define the proportions of the component gears, their speeds (rpm) and directions of rotations, and the resulting power splits. The formulas may be incorporated into simple computer programs oriented toward specific design requirements.

A geodetic approach for the recovery of global kinematic plate parameters

Abstract: Modern techniques of precise geodetic positioning are capable of monitoring global tectonic movements. We can avoid the tremendous effort of observing those point motions at every place on the earth, if we accept the model of rigid tectonic plates, which allows us to extrapolate from discrete point observations to the appertaining plates. The target of describing plate kinematics is the determination of its kinematic parameters, which are the coordinates of the rotation pole and the rotational velocity of each tectonic plate. A mathematical model is presented, which is capable of including geodetic observations (point coordinate shifts, distance changes) as well as geophysical quantities (sea floor spreading rates, earthquake slip vectors). The parameter estimation procedure is derived and demonstrated in simulated examples. Finally a global geodetic network for space techniques is designed, which provides an optimum parameter estimation.

The Development of Equations of Motion of Single-Arm Robots

Abstract: Procedures for efficiently obtaining the governing dynamical equations of motion for single-arm robotic systems are presented. The procedures are based upon Kane's dynamical equations. Euler parameters, partial velocities, partial angular velocities, relative coordinates, and generalized speeds are used in the development of the governing equations. This leads to explicit expressions for the equation coefficients in forms readily converted into computer algorithms for their numerical evaluation. The inverse problem of determining the joint forces and moments when the system kinematics is known also is addressed.

Analysis of small-aspect-ratio lifting surfaces in ground effect

Abstract: A lifting surface of small aspect ratio is analysed for motion with constant forward velocity, parallel and in close proximity to a rigid plane surface of infinite extent. The gap flow beneath the lifting surface is represented by a simple nonlinear solution in the cross-flow plane, and appropriate conditions are imposed at leading and trailing edges. The transition between these two conditions depends on the kinematics of the gap flow as well as the planform geometry. For steady-state motion of a delta wing with sufficiently large angle of attack, the transition point is upstream of the tail. For oscillatory heaving motion of a delta wing the transition point is cyclic if the heave velocity is sufficiently large. Illustrative computations of the lift force are presented.

A kinematic analysis of an upper extremity ballistic skill: the windmill pitch.

Abstract: The purposes of this study were (1) to determine the relative motions of the upper limb segments during the execution of the softball windmill pitch (2) to attempt to determine the effect of these motions on the performance of the skill. High speed motion picture film was used to calculate the kinematic parameters of the pitching arm segments during the pitch. Four highly-skilled pitchers were used as subjects. Each performed at least ten trials of the pitch, which were recorded by two motion picture cameras. The two trials with the fastest ball velocity for each of the four subjects were analyzed from a sagittal aspect only. The resulting kinematic analysis indicated that there was a definite proximal-to-distal sequence of these motions, with decelerations occurring in the proximal segments prior to release of the ball. It was concluded that one of the critical factors in highly-skilled performance of ballistic skills is the ability to decelerate such segments, which likely require very strong eccentric contractions of antagonistic muscle groups.

Kinematic Analysis and Simulation of Vertebral Motion Under Static Load—Part I: Kinematic Analysis

Abstract: The paper presents the kinematic analysis of motion segments of ten, humanlumbar spines. In order to achieve this objective, a spine fixture and a linkage transducer were designed. The spine fixture is capable of holding the motion segment in a prescribed plane of loading. With the designed fixture it becomes possible to apply three types of shear loads, and three types of bending loads. In addition, if desired, a compressive preload may be applied to a motion segment. The linkage transducer consists of six rotary potentiometers connected by seven rigid links. The transducer is capable of measuring all possible components of vertebral motion. The motion data in the motion segments of ten lumbar spine were collected under the influence of combined shear and bending loads applied in an incremental manner. Maximum shear load was 35.6 N and maximum bending load was 6780 N. mm. The motion segments did not show any appreciable difference in their motion beyond these loads. The motion segments were not subjected to any compressive preload. The range of motion data were collected in twelve loading planes 15 deg. apart. The characteristic vertebral motion may be described in terms of range of motion, its components, and the parameters associated with the screw motion. The paper presents data in the chart form to describe the kinematic characteristics of the lumbar motion segment.

Kinematic evolution of the junction of the San Andreas, Garlock, and Big Pine faults, California

Abstract: If the San Andreas fault with about 300 km of right slip, the Carlock fault with about 60 km of left slip, and the Big Pine fault with about 15 km of left slip are considered to have been contemporaneously active, a space problem at their high-angle junctions becomes apparent. Large crustal masses converge in the area of the junctions as a result of the simultaneous large displacements on the faults. We present here a model in which an early straight north-northwest–trending San Andreas deforms to its present bent configuration in response to a westward displacement of crust north of the Garlock fault. During this deformation, the crust north of the Garlock in the vicinity of the junction undergoes north-south shortening, while the fault junction migrates along the trace of the San Andreas fault to the southeast relative to its original position. As a result of this migration, the Mojave area is displaced to the east relative to the original junction position. We suggest a similar history in mirror image for the Big Pine fault and the areas of crust adjacent to it.