Showing papers on "Kinematics published in 1992"
01 Oct 1992
TL;DR: A methodology for exact robot motion planning and control that unifies the purely kinematic path planning problem with the lower level feedback controller design is presented.
Abstract: A methodology for exact robot motion planning and control that unifies the purely kinematic path planning problem with the lower level feedback controller design is presented. Complete information about a freespace and goal is encoded in the form of a special artificial potential function, called a navigation function, that connects the kinematic planning problem with the dynamic execution problem in a provably correct fashion. The navigation function automatically gives rise to a bounded-torque feedback controller for the robot's actuators that guarantees collision-free motion and convergence to the destination from almost all initial free configurations. A formula for navigation functions that guide a point-mass robot in a generalized sphere world is developed. The simplest member of this family is a space obtained by puncturing a disk by an arbitrary number of smaller disjoint disks representing obstacles. The other spaces are obtained from this model by a suitable coordinate transformation. Simulation results for planar scenarios are provided. >
1,912 citations
TL;DR: The measurements have identified that substantial angular and linear motions occur about and along each of the JCS axes during walking, and do not support the traditional view that the so-called 'screw home' mechanism of the knee joint operates during gait.
716 citations
01 Feb 1992
TL;DR: The kinematic and dynamic differential equations are further shown to be invertible due to the fact that they are written in quaternion space, and the highest order term of the rotation parameters can be expressed explicitly in closed form.
Abstract: Many useful identities pertaining to quaternion multiplications are generalized. Among them multiplicative commutativity is the most powerful. Since quaternion space includes the 3D vector space, the physical quantities related to rotations, such as angular displacement, velocity, acceleration, and momentum, are shown to be vector quaternions, and their expressions in quaternion space are derived. These kinematic and dynamic differential equations are further shown to be invertible due to the fact that they are written in quaternion space, and the highest order term of the rotation parameters can be expressed explicitly in closed form. >
396 citations
TL;DR: In this paper, a lumbar motion monitor (LMM) was developed for work assessment and clinical use, which is an exoskeleton of the spine that is instrumented so that instantaneous changes in trunk position, velocity and acceleration can be obtained in three-dimensional space.
285 citations
12 May 1992
TL;DR: This paper develops new methods for determining "optimal" hyper-redundant manipulator configurations based on a continuum formulation of kinematics that is computationally efficient on a single processor, and generates solutions in O(1) time for an N degree-of-freedom manipulator when implemented in parallel on O(N) processors.
Abstract: "Hyper-redundant" robots have a very large or infinite degree of kinematic redundancy. This paper develops new methods for determining "optimal" hyper-redundant manipulator configurations based on a continuum formulation of kinematics. This formulation uses a backbone curve model to capture the robot's essential macroscopic geometric features. The calculus of variations is used to develop differential equations, whose solution is the optimal backbone curve shape. We show that this approach is computationally efficient on a single processor, and generates solutions in O(1) time for an N degree-of-freedom manipulator when implemented in parallel on O(N) processors. For this reason, it is better suited to hyper-redundant robots than other redundancy resolution methods. Furthermore, this approach is useful for many hyper-redundant mechanical morphologies which are not handled by known methods.
244 citations
01 Oct 1992
TL;DR: A kinematic is presented that is fully parallel and actuator redundant that has the ability to partially control the internal forces, increase the workspace, remove singularities, and augment the dexterity.
Abstract: A kinematic is presented that is fully parallel and actuator redundant. Actuator redundancy refers to the use of more actuators than are strictly necessary to control the mechanism without increasing the mobility. The uses of this form of redundancy include the ability to partially control the internal forces, increase the workspace, remove singularities, and augment the dexterity. Optimization takes place based on several objective functions. The kinematic dexterity, the forces present at the actuators, and the uniformity of the dexterity over the workspace are all investigated as potential objectives. Global measures are derived from each of these quantities for optimization purposes. Instead, optimization of several factors is done simultaneously by specifying a primary objective and minimum performance standards for the secondary measures. >
203 citations
TL;DR: New dexterity indices that can be applied to planar and spatial manipulators that are based on the condition number of the Jacobian matrix of the manipulators which is known to be a measure of their kinematic accuracy are presented.
201 citations
01 Oct 1992
TL;DR: An efficient quantitative test for form closure valid for any number of contact points is formulated as a linear program, the optimal objective value of which provides a measure of how far a grasp is from losing form closure.
Abstract: An efficient quantitative test for form closure valid for any number of contact points is formulated as a linear program, the optimal objective value of which provides a measure of how far a grasp is from losing form closure. When the grasp does not have form closure, manipulation planning requires a means for predicting the object's stability and instantaneous velocity, given the joint velocities of the hand. The classical approach to computing these quantities is to solve the systems of kinematic inequalities corresponding to all possible combinations of separating or sliding at the contacts. All combinations resulting in the interpenetration of bodies or the infeasibility of the equilibrium equations are rejected. The remaining combination is consistent with all the constraints and is used to compute the velocity of the manipulated object and the contact forces, which indicate whether or not the object is stable. A linear program whose solution yields the same information as the classical approach, usually without explicit testing of all possible combinations of contact interactions, is formulated. >
201 citations
TL;DR: A mechanical analysis was made of the landing phase of three trained heel-toe runners, running at their preferred speed and style, implying that the runners investigated had no opportunity to control the rotations of body segments during the first part of the contact phase, other than by selecting a certain geometry of the body and muscular (co-)activation levels prior to touch-down.
176 citations
TL;DR: A dynamic model for a class of Stewart platform (six degrees of freedom parallel link robotic manipulators) is derived by using tensor representation, which gives all possible global solutions of a manipulator configuration for a given set of six leg lengths.
176 citations
Book•
01 Dec 1992
TL;DR: In this paper, the authors present a velocity analysis of Planar and Spatial Mechanisms and Machines, as well as a static and dynamic force analysis of planar and spatial Mechanisms.
Abstract: 1. Mechanisms and Machines: Basic Concepts. 2. Motion in Machinery. 3. Velocity Analysis of Planar and Spatial Mechanisms. 4. Acceleration Analysis of Planar and Spatial Mechanisms. 5. Design and Analysis of Cam and Follower Systems. 6. Spur Gears: Design and Analysis. 7. Helical, Worm, and Bevel Gears: Design and Analysis. 8. Drive Trains: Design and Analysis. 9. Static-Force Analysis. 10. Dynamic-Force Analysis. 11. Synthesis.
TL;DR: This paper addresses the motion and force control problem of multiple robot arms manipulating a cooperatively held object and shows that effective force regulation can be achieved even if little model information is available.
Patent•
11 Mar 1992
TL;DR: In this paper, a seven-degree-of-freedom robot arm with a six-degree of-freedom end effector is controlled by a processor employing a 6-by-7 Jacobian matrix for defining location and orientation of the end-effector in terms of the rotation angles of the joints, and a 1 (or more) by 7-or more-by 7 Jacobian matrices for defining kinematic functions constraining location or movement of selected portions of the arm.
Abstract: A seven-degree-of-freedom robot arm with a six-degree-of-freedom end effector is controlled by a processor employing a 6-by-7 Jacobian matrix for defining location and orientation of the end effector in terms of the rotation angles of the joints, a 1 (or more)-by-7 Jacobian matrix for defining 1 (or more) user-specified kinematic functions constraining location or movement of selected portions of the arm in terms of the joint angles, the processor combining the two Jacobian matrices to produce an augmented 7 (or more)-by-7 Jacobian matrix, the processor effecting control by computing in accordance with forward kinematics from the augmented 7-by-7 Jacobian matrix and from the seven joint angles of the arm a set of seven desired joint angles for transmittal to the joint servo loops of the arms. One of the kinematic functions constrains the orientation of the elbow plane of the arm. Another one of the kinematic functions minimizing a sum of gravitational torques on the joints. Still another one of the kinematic functions constrains the location of the arm to perform collision avoidance. Generically, one of the kinematic functions minimizes a sum of selected mechanical parameters of at least some of the joints associated with weighting coefficients which may be changed during arm movement. The mechanical parameters may be velocity errors or position errors or gravity torques associated with individual joints.
TL;DR: The role of some neural mechanisms in the adaptive control of limb compliance during preplanned mechanical interaction with objects is described and it is found that the gating of the stretch reflex responses around impact time is based on an internal model of limb geometry.
Abstract: The aim of this article is to describe the role of some neural mechanisms in the adaptive control of limb compliance during preplanned mechanical interaction with objects. We studied the EMG responses and the kinematic responses evoked by pseudorandom perturbations continuously applied by means of a torque motor before and during a catching task. The temporal changes of these responses were studied by means of an identification technique for time-varying systems. We found a transient reversal of EMG stretch reflex responses centered on the time of ball impact on the hand; this reversal results in a transient coactivation of antagonist muscles at both the elbow and the wrist. The kinematic responses describe the relation between torque input and position output. Thus, they provide a global measure of limb compliance. The changes in limb compliance during catching were quantified by computing error criteria either in the Cartesian coordinates of the hand or in the angular coordinates of the elbow and wrist joints. We found that only the hand compliance in Cartesian coordinates is consistently minimized around impact, in coincidence with the transient reversal of the stretch reflex responses. By contrast, the error criteria expressed in the angular coordinates of the joints have a variable time course and are not minimized around impact. It is known that hand compliance depends on both the pattern of muscle activities and the geometrical configuration of the limb. Therefore, the lack of consistent correlation between the changes in hand compliance and the changes in the geometrical configuration of the limb during catching indicates that the gating of the stretch reflex responses around impact time is based on an internal model of limb geometry.
TL;DR: The motion computation problem is formulated as a tracking problem in order to apply the extended Kalman filter and the tracking is performed in a prediction-matching-update loop in which multiple matches can be handled.
Abstract: We address the problem of computing the three-dimensional motions of objects in a long sequence of stereo frames. Our approach is bottom-up and consists of two levels. The first level deals with the tracking of 3D tokens from frame to frame and the estimation of their kinematics. The processing is completely parallel for each token. The second level groups tokens into objects based on their kinematic parameters, controls the processing at the low level to cope with problems such as occlusion, disappearance, and appearance of tokens, and provides information to other components of the system. We have implemented this approach using 3D line segments obtained from stereo as the tokens. We use classical kinematics and derive closed-form solutions for some special, but useful, cases of motions. The motion computation problem is then formulated as a tracking problem in order to apply the extended Kalman filter. The tracking is performed in a prediction-matching-update loop in which multiple matches can be handled. Tokens are labeled by a number called its support of existence which measures their adequation to the measurements. If this number goes beyond a threshold, the token disappears. The individual line segments can be grouped into rigid objects according to the similarity of their kinematic parameters. Experiments using synthetic and real data have been carried out and the results found to be quite good.
TL;DR: This article addresses the problem of the direct kinematics of parallel manipulators and the corollary problem of their assembly modes (i.e., the different ways of assembling these mechanisms when their geometry are fixed), and introduces a more general approach.
Abstract: In this article we address the problem of the direct kinematics of parallel manipulators and the corollary problem of their assembly modes (ie, the different ways of assembling these mechanisms when their geometry are fixed)As an example we consider first a 6-DOF manipulator with a trianglular mobile plate and variable links lengths A geometric proof is presented to show that the number of assembly modes is at most 16 Then we show that solving the direct kinematics problem is equivalent to solve a l6th-order polynomial in one variable, which is presented We exhibit one example for which there are effectively 16 assembly modesWe extend then the results of this example to various architec tures of parallel manipulators with a triangular mobile plate (among them the famous Stewart platform) Unfortunately the method used in those cases cannot be extended to the most general parallel manipulators We introduce a more general approach and present the results of this method on a particular case
TL;DR: In this article, a kinematic analysis of seven-degree-of-freedom serial link spatial manipulators with revolute joints is presented, where the redundancy is parameterized by a scalar variable that defines the angle between the arm plane and a reference plane.
Abstract: This article presents a kinematic analysis of seven-degree-of-freedom serial link spatial manipulators with revolute joints. To uniquely determine the joint angles for a given end-effector position and orientation, the redundancy is parameterized by a scalar variable that defines the angle between the arm plane and a reference plane. The forward kinematic mappings from joint space to end-effector coordinates and arm angle and the augmented Jacobian matrix that gives end-effector and arm angle rates as functions of joint rates are presented. Conditions under which the augmented Jacobian becomes singular are also given and are shown to correspond to the arm being either at a kinematically singular configuration or at a nonsingular configuration for which the arm angle ceases to parameterize the redundancy.
12 May 1992
TL;DR: A representation of the support friction of a sliding object is presented, and the results of the force analysis are independent of the exact support distribution of the object, resulting in a manipulation primitive: stable rotational pushing.
Abstract: The author presents a method for determining the possible instantaneous motions of a sliding object during multiple contact pushing. The approach consists of two components: a kinematic analysis considering kinematic motion constraints, and a force analysis considering force constraints on the motion. A representation of the support friction of a sliding object is presented, and the results of the force analysis are independent of the exact support distribution of the object. The analysis results in a manipulation primitive: stable rotational pushing. This primitive may be used for precise placement operations by pushing. >
01 Jan 1992
TL;DR: In this article, the concept of critical slope or taper was expanded through the use of finite element models to consider the kinematics and dynamics of a deforming Coulomb wedge, and the numerical technique adopts a Coulomb failure criterion and isotropic plastic flow in a velocity-based Eulerian formulation.
Abstract: Deformation and structural relationships in accretionary prisms and fold and thrust belts are the result of dynamic changes in the size, geometry, or strength of the deforming wedge and its boundary conditions. The concepts of critical slope or taper that have been successful in explaining the static geometry and state of stress in a Coulomb wedge can be expanded through the use of finite element models to consider the kinematics and dynamics of a deforming Coulomb wedge. The numerical technique adopts a Coulomb failure criterion and isotropic plastic flow in a velocity-based Eulerian formulation. This formulation allows for very large deformation to be accommodated by a numerical mesh that remains fixed in space, deforming only to follow the movement of the upper surface.
Book•
22 Apr 1992
TL;DR: Part 1 Introduction: kinematic analysis degrees of freedom analysis characterizing the linkage domain comparison with existing techniques the future and future directions toward solving the general constraint satisfaction problem.
Abstract: Part 1 Introduction: kinematic analysis degrees of freedom analysis characterizing the linkage domain comparison with existing techniques the future. Part 2 Mechanical linkages and kinematics: machines, mechanisms and linkages kinematic simulation - examples kinematic simulation - a formal definition existing mechanisms simulation methods modeling the kinematics of linkages with constraints. Part 3 Degrees of freedom analysis: the metaphor of incremental assembly the sybmolic model the numerical model example 1 - the brick example 2 - two sticks example 3 - four-bar linkage overview of the position analysis algorithm. Part 4 Action and locus analysis: the plan fragment table locus tables extended locus tables. Part 5 Chain and loop analysis: a graph representatin of constraint problems loop analysis - topological rigidity chain and loop rewriting solving loops degeneracies. Part 6 Position analysis: the position analysis algorithm runtime complexity completeness in the mechanisms domain. Part 7 Comparison with previous approaches: graphical analysis of mechanisms numerical solution techniques symbolic solution techniques empirical comparison with ADAMS other related work limitations of degrees of freedom analysis. Part 8 Conclusion: discussion future directions toward solving the general constraint satisfaction problem. Appendices: assembly procedure example the TLA target marchine the plan fragment table rigid connections between geoms loops of three geoms empirical comparisons of TLA and ADAMS.
TL;DR: The experiments presented here extend recent findings about KR to a paradigm involving kinematic feedback, and suggest that this feedback may influence learning in ways parallel to KR.
Abstract: Although the study of feedback about goal achievement (knowledge of results, KR) has been important for the development principles of augmented information feedback in simple skills, there is reason to question the generalizability of these findings to many common learning situations. A more appropriate type of information for skill learning appears to be augmented kinematic (or kinetic) feedback regarding the movement pattern. The experiments presented here extend recent findings about KR to a paradigm involving kinematic feedback. In Experiment 1, we examined how several kinds of temporal and spatial kinematic information supplement KR in learning. Spatial kinematic variables were more effective than temporal variables, as indicated by performance in a retention test without kinematic feedback. In Experiment 2, we manipulated the schedule of augmented kinematic feedback in a method that paralleled previous KR work. We contrasted averaged schedules of augmented feedback, in which information was given either after every trial or as averaged information after every set of five trials. On retention tests without kinematic feedback given 1 day and 1 week after acquisition, averaged schedules led to enhanced performance over an every-trial format. Together, these results begin to define the variables important in kinematic feedback, and suggest that this feedback may influence learning in ways parallel to KR.
TL;DR: A model of left ventricular kinematics is essential to identify the fundamental physiological modes of LV deformation during a complete cardiac cycle as observed from the motion of a finite number of markers embedded in the LV wall.
TL;DR: Normal human subjects grasped a 3-D isometric handle with an otherwise unrestrained, pronated hand and exerted forces continuously to draw circles, ellipses and lemniscates (figure-eights) in specified planes in the presence or absence of a3-D visual force-feedback cursor and a visual template.
Abstract: Normal human subjects grasped a 3-D isometric handle with an otherwise unrestrained, pronated hand and exerted forces continuously to draw circles, ellipses and lemniscates (figure-eights) in specified planes in the presence or absence of a 3-D visual force-feedback cursor and a visual template. Under any of these conditions and in all subjects, a significant positive correlation was observed between the instantaneous curvature and angular velocity, and between the instantaneous radius of curvature and tangential velocity; that is, when the force trajectory was most curved, the tangential velocity was lowest. This finding is similar to that obtained by Viviani and Terzuolo (1982) for 2-D drawing arm movements and supports the notion that central constraints give rise to the relation between geometric and kinematic parameters of the trajectory.
TL;DR: In this paper, a rigorous, kinematic description of the stretching and alignment of infinitesimal material elements in general flow fields is presented, and an evolution equation is derived, in the Lagrangian frame, for the alignment angles between a material element and the principal axes of strain.
Abstract: A rigorous, kinematic description of the stretching and alignment of infinitesimal material elements in general flow fields is presented. An evolution equation is derived, in the Lagrangian frame, for the alignment angles between a material element and the principal axes of strain. The equation identifies the precise roles played by the local angular velocity and the rotation of the strain axes in the alignment process and provides the framework in which to investigate the extent to which the straining field is ‘persistent ’. This general kinematical picture is specialized to study line and vortex stretching in fluid flows and analytically predicts the numerically observed alignment of the vorticity vector with the intermediate strain axis. The alignment equations are solved exactly for a number of special flow fields and investigated numerically for the ABC and STF flows. The kinematic formalism and numerical phenomenology suggests the use of new criteria to analyse the material element stretching properties of large-scale numerical simulations.
12 May 1992
TL;DR: A novel design of a holonomic omnidirectional vehicle that allows the vehicle to maneuver in an arbitrary direction from an arbitrary configuration on a plane significantly simplifies control problems and improves positioning accuracy.
Abstract: A novel design of a holonomic omnidirectional vehicle is introduced. The holonomic mechanism allows the vehicle to maneuver in an arbitrary direction from an arbitrary configuration on a plane. This significantly simplifies control problems and improves positioning accuracy. A fundamental method of obtaining omnidirectional motion with holonomic constraints with the floor, using a mechanism with spherical tires, is presented. Kinematic analysis of this mechanism gives the vehicle Jacobian relating actuator velocities to the vehicle velocity components. Analysis of lateral tire slip during vehicle rotation allows slip reduction methods. A prototype vehicle using this special mechanism and a computerized control system is designed and tested. In addition to rotation, the vehicle can perform very accurate translational motions, in two orthogonal directions, arbitrarily termed forward and sideways. Motions in these two degrees of freedom are decoupled from each other and are insensitive to variations in ground friction coefficient. >
TL;DR: In this paper, the inverse of the manipulator Jacobian matrix is identified as causing the kinematic instability of the hybrid position/force control scheme, and sufficient conditions for kine matic stability are proposed to determine when a system may become unstable without requiring a complete system analysis.
Abstract: This article will show conclusively that "kinematic instability" is not inherent to the hybrid position/force control scheme of robot manipulators but is a result of an incomplete and inap propriate formulation. The inverse of the manipulator Jacobian matrix is identified as causing the kinematic instability of the hybrid position/force control scheme. Linear algebra is used to explain clearly the implications of mapping between vec tor spaces and to reveal why the inverse of the manipulator Jacobian matrix should not be used in hybrid position/force control. A generalized architecture for hybrid position/force control is presented that can influence both joint positions and torques. This generalized formulation also includes the control of redundant manipulators. Some sufficient conditions for kine matic stability are proposed to determine when a system may become unstable without requiring a complete system analysis. A stable hybrid position/force control scheme is given and is demonstrated using an exa...
TL;DR: A system of articulated motion design which offers a full combination of both direct and inverse kinematic control of the joint parameters is proposed, leading to a new methodology of joint‐motion editing which is demonstrated through the improvement of a functional model of human walking.
Abstract: A new approach for the animation of articulated figures is presented. The authors propose a system of articulated motion design which offers a full combination of both direct and inverse kinematic control of the joint parameters. Such an approach allows an animator to specify interactively goal-directed changes to existing sampled joint motions, resulting in a more general and expressive class of possible joint motions. The fundamental idea is to consider any desired-joint space motion as a reference model inserted into the secondary task of an inverse kinematic control scheme. The approach profits from the use of half-space Cartesian main tasks in conjunction with a parallel control of the articulated figure called the coach-trainee metaphor. In addition, a transition function is introduced so as to guarantee the continuity of the control. The resulting combined kinematic control scheme leads to a new methodology of joint-motion editing which is demonstrated through the improvement of a functional model of human walking
01 Jan 1992
TL;DR: This thesis addresses manipulation tasks that involve two rigid polygonal objects interacting in a plane and defines a collection of generic algorithms that analyze the kinematic, static, dynamic, and motion-specification aspects of a given task.
Abstract: This thesis addresses the problem of producing reliable solutions to manipulation tasks. Such tasks are strongly influenced by the task geometry, mechanics, and uncertainty. This thesis addresses these issues by applying the techniques of classical mechanics, and extends these techniques to include task geometry and uncertainty. In particular, the thesis addresses manipulation tasks that involve two rigid polygonal objects interacting in a plane; examples include linear pushing, compliant motion, and placing-by-dropping tasks.
For this class of tasks, the thesis defines a collection of generic algorithms that analyze the kinematic, static, dynamic, and motion-specification aspects of a given task. These algorithms identify a continuous bounded set of actions that will retiably achieve the task goal, despite uncertainty in every physical parameter except object shape. The algorithms perform a kinematic analysis to construct the set of reachable ($x$, $y$, $\theta$) task configurations, a static analysis to identify the configurations where equilibrium is possible, a dynamic analysis to identify a set of initial configurations that converge to the goal, and a coordinate transformation to identify a set of commanded motions that will achieve the goal.
The kinematic and static analysis algorithms have been fully implemented, and the dynamic analysis algorithms have been partially implemented. These programs were used to synthesize linear pushing actions, to analyze a part interacting with an orienting fixture, and to synthesize placing-by-dropping actions. A series of physical experiments were performed to test the validity of the programs' physical predictions; no failures were observed in these experiments, some of which included over 1200 trials.
This thesis represents a step toward the application of classical mechanics to general manipulation problems; many open problems remain. The thesis presents a discussion of possible extensions of this work to enhance its generality, as well as a discussion of task domains that appear to require a completely different approach.
TL;DR: In this paper, an interacting multiple model (IMM) algorithm that includes a constant velocity model, a constant speed model with the kinematic constraint for constant speed targets, and the exponentially increasing acceleration (EIA) model for maneuver response is proposed.
Abstract: The interacting multiple model (IMM) algorithm uses multiple models that interact through state mixing to track a target maneuvering through an arbitrary trajectory. However, when a target maneuvers through a coordinated turn, the acceleration vector of the target changes magnitude and direction, and the maneuvering target models commonly used in the IMM (e.g., constant acceleration) can exhibit considerable model error. To address this problem an IMM algorithm that includes a constant velocity model, a constant speed model with the kinematic constraint for constant speed targets, and the exponentially increasing acceleration (EIA) model for maneuver response is proposed. The constant speed model utilizes a turning rate in the state transition matrix to achieve constant speed prediction. The turning rate is calculated from the velocity and acceleration estimates of the constant speed model. The kinematic constraint for constant speed targets is utilized as a pseudomeasurement in the filtering process with the constant speed model. Simulation results that demonstrate the benefits of the EIA model and the kinematic constraint to the IMM algorithm are given. The tracking performance of the proposed IMM algorithm is compared with that of an IMM algorithm utilizing constant velocity and constant turn rate models.