Scheduled System Maintenance on May 29th, 2015:
IEEE Xplore will be upgraded between 11:00 AM and 10:00 PM EDT. During this time there may be intermittent impact on performance. We apologize for any inconvenience.
By Topic

Robotics and Automation, IEEE Transactions on

Issue 5 • Date Oct 1990

Filter Results

Displaying Results 1 - 11 of 11
  • Using camera motion to estimate range for robotic parts manipulation

    Publication Year: 1990 , Page(s): 509 - 521
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1296 KB)  

    A technique is described for determining a depth map of parts in bins using optical flow derived from camera motion. Simple programmed camera motions are generated by mounting the camera on the robot end effector and directing the effector along a known path. The results achieved using two simple trajectories, where one is along the optical axis and the other is in rotation about a fixation point, are detailed. Optical flow is estimated by computing the time derivative of a sequence of images, i.e. by forming differences between two successive images and, in particular, matching between contours in images that have been generated from the zero crossings of Laplacian of Gaussian-filtered images. Once the flow field has been determined, a depth map is computed utilizing the parameters of the known camera trajectory. Empirical results are presented for a calibration object and two bins of parts; these are compared with the theoretical precision of the technique, and it is demonstrated that a ranging accuracy on the order of two parts in 100 is achievable View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Relationship between payload and speed in legged locomotion systems

    Publication Year: 1990 , Page(s): 570 - 577
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    The dependency of payload on vehicle operating speed, which is a problem peculiar to legged locomotion, is examined via a case study of a hexapod using wave gaits. The treatment presented is confined to systems using quasi-statically stable gaits. A set of closed-form analytic expressions describing the payload-speed relationship has been obtained. The solution is based on the assumption of equal leg compliances. The utility of such relationships lies in determining the allowable payload given the vehicle speed and weight or, conversely, in preplanning the payload to be carried and determining the maximum speed at which the vehicle can operate safely View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • LP problem formulation of extremal path accelerations for a rigid body handled by multiple linkages

    Publication Year: 1990 , Page(s): 533 - 539
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB)  

    The minimum traveling time of a rigid body along a specified geometric path can be achieved by switching between extremal allowable accelerations. A linear programming (LP) problem is formulated to obtain such extreme accelerations for a body handled by multiple robotic manipulators or robotic fingers. Both rigid grasping and grasping with point contacts have been treated View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Torque-limited path following by online trajectory time scaling

    Publication Year: 1990 , Page(s): 554 - 561
    Cited by:  Papers (61)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    A feedback scheme for path following by trajectory time scaling is presented. The scheme is used in execution of fast trajectories along a geometric path, where the motion is limited by torque constraints. The time scaling is done by using a secondary controller that modifies a nominal trajectory during motion. The nominal, high-performance trajectory typically leads to torques that are at the limits, which leaves no control authority to compensate for modeling errors and disturbances. By modifying the time scaling of the nominal trajectory when the torques saturate, closed-loop action is possible. A key idea is that a scalar quantity (the path acceleration) is modified, resulting in coordinated adjustment of the individual joint motions. Two algorithms for online trajectory scaling are presented. One is based on online bounds on path acceleration, and one is designed to handle nominal minimum time trajectories. The functionality of the secondary controller is verified by simulations and experiments View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A natural modal expansion for the flexible robot arm problem via a self-adjoint formulation

    Publication Year: 1990 , Page(s): 601 - 603
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB)  

    The equations of motion of a flexible robot arm consist of a coupled partial differential equation describing the arm's transverse vibrations and an ordinary differential equation describing the hub's rigid motion. Many researchers obtained a solution using a modal expansion based on the arm's equation alone, which has erroneous eigenfunctions and eigenvalues. A novel method is presented for obtaining an equivalent but self-adjoint form for the problem. This self-adjoint form leads to a natural modal expansion, where the equations decouple. This method is used to show that the effect of the hub-arm model coupling depends exclusively on the hub-inertia-to-arm-mass ratio. The need for a self-adjoint form arises in many control applications. This is because, typically, the control design is based on approximate models, and in order to guarantee robust performance, a prior estimate of the approximation error is required. When a self-adjoint form is available, obtaining approximate modes and the associated error bounds becomes an easy task View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A free gait for generalized motion

    Publication Year: 1990 , Page(s): 597 - 600
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    A method is presented for the generation of a locally optimal free gait for 2-D generalized motion of a quadruped walking machine. It employs a heuristic graph search procedure based on the A* algorithm. The method essentially looks into the consequences of a move to a certain depth before actually committing to it. Deadlocks and inefficiencies are thus sensed well in advance and avoided View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fast collision avoidance for manipulator arms: a sequential search strategy

    Publication Year: 1990 , Page(s): 522 - 532
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (880 KB)  

    A novel sequential strategy is presented to plan collision-free motions for a manipulator arm (such as PUMA 260). The basic idea behind the approach is to plan the motion of each link successively, starting from the base link. Suppose that the motion of links until link i (including link i) has been planned. This already determines the path of one end (the proximal end) of link i+1. The motion of link i+1 is now planned along this path by controlling the degree of freedom associated with it-a two-dimensional motion planning problem. This strategy results in one one-dimensional (the first link is degenerate) and n-1 two-dimensional problems instead of one n-dimensional problem for an n-link manipulator arm. In most reasonable cases, the strategy should quickly find a path. At the very least, it will form a front end to a more complete planner View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimal grid-free path planning across arbitrarily contoured terrain with anisotropic friction and gravity effects

    Publication Year: 1990 , Page(s): 540 - 553
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1252 KB)  

    The authors address anisotropic friction and gravity effects as well as ranges of impermissible-traversal headings due to overturn danger or power limitations. The method does not require imposition of a uniform grid, nor does it average effects in different directions, but reasons about a polyhedral approximation of terrain. It reduces the problem to a finite but provably optimal set of possibilities and then uses A* search to find the cost-optimal path. However, the possibilities are not physical locations but path subspaces. The method also exploits the insight that there are only four ways to optimally traverse an anisotropic homogeneous region: (1) straight across without braking, which is the standard isotropic-weighted-region traversal; (2) straight across without braking but as close as possible to a desired impermissible heading; (3) making impermissibility-avoiding switchbacks on the path across a region; and (4) straight across with braking. The authors prove specific optimality criteria for transitions on the boundaries of regions for each combination of traversal types View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Affine invariant model-based object recognition

    Publication Year: 1990 , Page(s): 578 - 589
    Cited by:  Papers (84)  |  Patents (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1252 KB)  

    New techniques are described for model-based recognition of the objects in 3-D space. The recognition is performed from single gray-scale images taken from unknown viewpoints. The objects in the scene may be overlapping and partially occluded. An efficient matching algorithm, which assumes affine approximation to the prospective viewing transformation, is proposed. The algorithm has an offline model preprocessing (shape representation) phase which is independent of the scene information and a recognition phase based on efficient indexing. It has a straightforward parallel implementation. The algorithm was successfully tested in recognition of industrial objects appearing in composite occluded scenes View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Symmetrically actuated double pointing systems: the basis of singularity-free robot wrists

    Publication Year: 1990 , Page(s): 562 - 569
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    An analysis is conducted of symmetrically actuated double pointing systems, which are two spherical pointing systems connected serially with a common center. The double pointing systems have four degrees of freedom interrelated by two constraint functions, reducing the systems to two independent degrees of freedom. Together, these constraint functions result in a symmetry in the motion of corresponding links in each pointing system of the double system. A singularity analysis is presented of a generalized symmetrically actuated double pointing system in order to prove that it and the systems derived from it have maximal singularity-free workspaces. Closed-form solutions to the inverse position and velocity problems are presented along with different types of kinematic arrangements. Any of the double pointing systems presented can serve as the basis of a singularity-free wrist View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic digital distance maps in two dimensions

    Publication Year: 1990 , Page(s): 590 - 597
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1056 KB)  

    An efficient means for dealing with obstacles in motion is provided to extend the usefulness of digital distance maps. An algorithm is presented that allows one to compute what portions of a map will probably be affected by an obstacle's motion. The algorithm is based on an analysis of the distance transform as a problem in wave propagation. The regions that must be checked for possible updates when an obstacle moves are those that are in its or in the shadow of obstacles that are partially in the shadow of the moving obstacle. The technique can handle multiple fixed goals, multiple obstacles moving and interacting in an arbitrary fashion, and it is independent of the technique used for calculation of the distance map. The algorithm is demonstrated on a number of synthetic two-dimensional examples, and example timing results are reported View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

This Transactions ceased production in 2004. The current retitled publications areIEEE Transactions on Automation Science and Engineering and IEEE Transactions on Robotics.

Full Aims & Scope