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Robotics and Automation, IEEE Transactions on

Issue 1 • Date Feb 1997

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Displaying Results 1 - 14 of 14
  • Adaptive model-based hybrid control of geometrically constrained robot arms

    Publication Year: 1997 , Page(s): 105 - 116
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    This paper reports comparative experiments with a new model-based adaptive force control algorithm for robot arms. This controller provides simultaneous position and force trajectory tracking of a robot arm whose tool tip is in point contact with a smooth rigid surface. The algorithm is provably stable with respect to the commonly accepted rigid-body nonlinear dynamical model for robot arms. Comparative experiments show the new adaptive model-based controller to provide performance superior to that of both nonmodel-based controllers and nonadaptive controllers over a wide range of operating conditions View full abstract»

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  • A framework for robot motion planning with sensor constraints

    Publication Year: 1997 , Page(s): 61 - 73
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1272 KB)  

    Visual feedback can play a crucial role in a dynamic robotic task such as the interception of a moving target. To utilize the feedback effectively, there is a need to develop robot motion planning techniques that also take into account properties of the sensed data. We propose a motion planning framework that achieves this with the help of a space called the perceptual control manifold (PCM) defined on the product of the robot configuration space and an image-based feature space. We show how the task of intercepting a moving target can be mapped to the PCM, using image feature trajectories of the robot end-effector and the moving target. This leads to the generation of motion plans that satisfy various constraints and optimality criteria derived from the robot kinematics, the control system, and the sensing mechanism. Specific interception tasks are analyzed to illustrate this vision-based planning technique View full abstract»

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  • A structure-oriented approach to assembly sequence planning

    Publication Year: 1997 , Page(s): 14 - 29
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    An assembly sequence planner is a system which, given a description of an assembly to be manufactured, identifies subassemblies and generates high-level plans for the construction of the each subassembly, including the final assembly. Previous research has shown that feasible plans can be efficiently produced for large assemblies, but the generation of good plans has met with less success. Not only are there difficulties in defining “good plans,” but all published methods for finding good plans have computational complexities that make them unlikely to be practical for large assemblies. This paper shows that representing an assembly as a hierarchy of assembly structures can overcome many of these difficulties. A planner is described which uses the structure hierarchy both as a framework for structure-dependent definitions of a good plan, and as a tool for finding good plans more rapidly by using high-level expert advice, by reusing subplans for repeated substructures, and by not fully optimizing the plan. Analytical and experimental results are presented to demonstrate the effectiveness of the approach View full abstract»

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  • Translating relay ladder logic for CCM solving

    Publication Year: 1997 , Page(s): 148 - 153
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    Relay ladder logic (RLL) continues to be offered in more PLC systems than any other modeling language. Solving large RLL models with array scanning or instruction list interpreter techniques is not feasible in many applications where large amounts of inactive logic are necessary to insure quality control and safety. An improved translation algorithm is described for converting RLL models into model data for the clause counter map (CCM) solver, whose scan time depends on the current scan activity, rather than the size of the control logic View full abstract»

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  • Nonlinear path control in automated vehicle guidance

    Publication Year: 1997 , Page(s): 49 - 60
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (956 KB)  

    The problem of path control of automatically guided vehicles along a desired trajectory is considered where both lateral and longitudinal dynamics have been incorporated in the vehicle model. It is shown that a nonlinear decoupling controller and pole-placement can be used to obtain a closed-loop behavior that is independent of the vehicle operation point. For the pole-placement, the entire state is necessary. Since the sideslip is not available from measurements, an observer is applied, estimating the sideslip. Due to the steady state errors imposed by the nonlinear controller, a predictive filter is used to calculate this steady state error. The effectiveness of this controller is then demonstrated by simulations View full abstract»

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  • Mechanical filtering effect of elastic cover for tactile sensor

    Publication Year: 1997 , Page(s): 128 - 132
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (676 KB)  

    Tactile sensors are ordinarily covered with an elastic cover to protect the sensor from being damaged by shock or chemical contamination. The cover, however, greatly decreases the sensor's spatial resolution. This effect becomes serious in the fabrication of a high-spatial-resolution sensor, even if the cover is only 0.2 mm thick, when the sensor requires a spatial resolution of less than 1 mm. This paper analyzes the low-pass spatial filtering effect of the cover, calculates the filtering gain for different types of elastic cover materials using the finite-element method, and gives preliminary experimental results View full abstract»

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  • Stable control of a simulated one-legged running robot with hip and leg compliance

    Publication Year: 1997 , Page(s): 96 - 104
    Cited by:  Papers (55)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    We present a control strategy for a simplified model of a one-legged running robot which features compliant elements in series with hip and leg actuators. For this model, proper spring selection and initial conditions result in “passive dynamic” operation close to the desired motion, without any actuation. However, this motion is not stable. Our controller is based on online calculations of the desired passive dynamic motion which is then parametrized in terms of a normalized “locomotion time”. We show in simulation that the proposed controller stabilizes a wide range of velocities and is robust to modeling errors. It also tracks changes in desired robot velocity and remains largely passive despite a fixed set of springs, masses, and inertias. Comparisons of simulated runs with direct hip actuation show 95% hip actuation energy savings at 3 m/s. Such energy savings are critical for the power autonomy of electrically actuated legged robots View full abstract»

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  • Hierarchical production controls in a stochastic two-machine flowshop with a finite internal buffer

    Publication Year: 1997 , Page(s): 1 - 13
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    This paper presents an asymptotic analysis of hierarchical production planning in a manufacturing system with two tandem machines that are subject to breakdown and repair. The system produces a single product, whose rate of demand over time is given to be constant. The problem is formulated as a continuous-time dynamic programming problem in which the objective is to minimize the cost of production, inventories, and backlogs. The size of the buffer between the two machines is assumed to be finite. As the rates of change in machines' states approach infinity, the analysis results in a limiting problem in which the stochastic machine capacity is replaced by the average capacity. The value function for the original problem is shown to converge to the value function of the limiting problem. Both open-loop and feedback controls for the original problem are constructed from near-optimal controls of the limiting problem in a way which guarantees their asymptotic optimality as the rates of changes in machines' states become large in comparison to the discount rate. The convergence rate of the value function for the original problem to that of the limiting problem together with the error estimate for the constructed asymptotic optimal controls are obtained. In addition, the constructed feedback control is compared to the Kanban control policy for the stochastic two-machine flowshop View full abstract»

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  • Scaling laws for linear controllers of flexible link manipulators characterized by nondimensional groups

    Publication Year: 1997 , Page(s): 117 - 127
    Cited by:  Papers (8)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    When constructing large robotic manipulators or space structures, it is advisable to begin with a small-scale prototype on which to perform the design, analysis, and debugging. To ensure that the results obtained on the scale-model apply directly to the actual manipulator, it is necessary that the prototype and the original robot are dynamically equivalent. This paper examines the single flexible link (SFL) manipulator. Dimensional analysis is used to identify the nondimensional groups for the SFL. These groups are present in the corresponding nondimensional equations of motion, which are also derived. To account for inherent manufacturing imprecision, tolerances are developed for the nondimensional groups. Scaling laws for continuous-time and discrete-time controllers are developed for dynamically equivalent SFL systems. These theoretical scaling laws are verified experimentally for an H and a PD control strategy View full abstract»

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  • Nonlinear adaptive control for flexible-link manipulators

    Publication Year: 1997 , Page(s): 140 - 148
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    As has been realized, the flexible-link manipulators have attracted more and more attention from robot control theorists and/or robot users because of its various potential advantages. But since the control degree-of-freedom is much less than that of the system, many control strategies which succeed in the conventional rigid robot control cannot be directly used in the flexible robot control problems. In this paper, a nonlinear control scheme has been proposed as a solution to these control problems. In particular, to cope with the existing model uncertainty, an adaptive version of this nonlinear control law has been proposed. Stability proof of the overall closed-loop system is then given via Lyapunov analysis. In addition, extensive experimental results are also provided to demonstrate the effectiveness of the proposed controller View full abstract»

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  • Toward automatic robot instruction from perception-mapping human grasps to manipulator grasps

    Publication Year: 1997 , Page(s): 81 - 95
    Cited by:  Papers (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1348 KB)  

    Our approach of programming a robot is by direct human demonstration. The system observes a human performing the task, recognizes the human grasp, and maps it onto the manipulator. This paper describes how an observed human grasp can be mapped to that of a given general-purpose manipulator for task replication. Planning the manipulator grasp based upon the observed human grasp is done at two levels: the functional and physical levels. Initially, at the functional level, grasp mapping is achieved at the virtual finger level; the virtual finger is a group of fingers acting against an object surface in a similar manner. Subsequently, at the physical level, the geometric properties of the object and manipulator are considered in fine-tuning the manipulator grasp. Our work concentrates on power or enveloping grasps and the fingertip precision grasps. We conclude by showing an example of an entire programming cycle from human demonstration to robot execution View full abstract»

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  • Autonomous mobile robot global motion planning and geometric beacon collection using traversability vectors

    Publication Year: 1997 , Page(s): 132 - 140
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    Approaches in global motion planning (GMP) and geometric beacon collection (for self-localization) using traversability vectors have been developed and implemented in both computer simulation and actual experiments on mobile robots. Both approaches are based on the same simple, modular, and multifunctional traversability vector (t-vector). Through implementation it has been found that t-vectors reduce the computational requirements to detect path obstructions, Euclidean optimal via-points, and geometric beacons, as well as to identify which features are visible to sensors. Environments can be static or dynamic and polygons are permitted to overlap (i.e., intersect or be nested). While the t-vector model does require that polygons be convex, it is a much simpler matter to decompose concave polygons into convex polygon sets than it is to require that polygons not overlap, which is required for many other GMP models. T-vectors also reduce the data size and complexity of standard V-graphs and variations thereof. This paper presents the t-vector model so that the reader can apply it to mobile robot GMP and self-localization View full abstract»

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  • Object motion and structure recovery for robotic vision using scanning laser range sensors

    Publication Year: 1997 , Page(s): 74 - 80
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    Although many algorithms have been developed for motion estimation from range images, none are suited for use with scanning laser sensors. In this paper, the feature-based motion transformation model is restated to incorporate the nonzero pixel sampling rate of laser range cameras and a novel iterative, linear, feature-based technique for determining the 3D motion transformation of moving objects is developed using this new model. A technique is then presented which employs the motion recovered using the iterative algorithm to remove the structural distortion of the object in the range map. The performance of the motion recovery method is verified using simulated and experimental data View full abstract»

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  • Impact of fieldbus on communication in robotic systems

    Publication Year: 1997 , Page(s): 30 - 48
    Cited by:  Papers (18)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    The aim of this paper is to discuss the problems relating to communication in distributed process control, highlighting the limits of traditional centralized communication systems based on point-to-point connections. The paper shows the real advantages that can be obtained by using a distributed common-bus communication system in time-critical process control applications, highlighting its impact on the architecture of control systems from the point of view of both hardware and software. Particular reference is made to the International Electrotechnical Commission/Instrument Society of America (IEC/ISA) communication system which is close to becoming an international standard. In particular, the solution based on the use of the distributed common-bus communication protocol is applied to the control of an orange-picking robot, which had previously been implemented in a traditional way using point-to-point communications. The choice of a case study referring to a robot control system seems an appropriate benchmark for the real potential of the fieldbus because the processes involved in a robot control system have highly critical time constraints which may stress the fieldbus communication system. The paper presents a qualitative analysis of the advantages that can be obtained by introducing the fieldbus into the orange picking robot control system. The analysis gives a detailed illustration of the hardware and software modification needed to replace the traditional point-to-point control systems of the orange picking robot with the fieldbus. Then an evaluation of the performance of fieldbus system is provided. The evaluation is made by modeling and simulating the distributed communication system with transition timed Petri nets (TTPNs). The results obtained in the study as a whole confirm the authors' conviction that, by careful analysis, it is possible and advantageous even in difficult cases to replace classical centralized point-to-point control systems with distributed systems based on use of the fieldbus View full abstract»

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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