Most of conventional anti-sway control systems focus on control schemes with a vision system. Because it has many drawbacks such as difficult maintenance and high cost, a new vision-sensorless anti-sway control system...
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Most of conventional anti-sway control systems focus on control schemes with a vision system. Because it has many drawbacks such as difficult maintenance and high cost, a new vision-sensorless anti-sway control system for container cranes is proposed in this paper. The proposed system includes a multivariable state feedback anti-sway controller with an integrator, a sway velocity observer, and a sway angle detection method in which an inclinometer is used instead of the vision system. While conventional researches have used a simple pendulum model (single wire rope), the hoist wire rope structure of a real container crane is considered and the motion of the head block (spreader) is analyzed. An elaborate pilot crane is constructed to verify the performance of the proposed system. It is a 1/4-scaled model of a real rail mounted quayside crane. The feasibility and the performance of the proposed system are synthetically verified on the pilot crane. Also, experiments are carried out on the real container crane (rubber tyred gantry crane) in the commercial site to verify the performance of the proposed control system.
For an object grasped by a robot hand to work in the compliance control domain, we first analyze a necessary condition for successful stiffness modulation in the operational space. Next, we propose a compliance contro...
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For an object grasped by a robot hand to work in the compliance control domain, we first analyze a necessary condition for successful stiffness modulation in the operational space. Next, we propose a compliance control method for robot hands which consist of two steps: the RIFDS (resolved inter-finger decoupling solver) decomposes the desired compliance characteristic specified in the operational space into the compliance characteristic in the fingertip space without inter-finger coupling; and the RIJDS (resolved inter-joint decoupling solver) decomposes the compliance characteristic in the fingertip space into the compliance characteristic in the joint space without inter-joint coupling. According to the analysis results, the finger structure should be biomimetic in the sense that either kinematic redundancy or force redundancy are required to implement the proposed compliance control scheme. Five-bar fingered robot hands are treated as illustrative examples to implement the proposed compliance control method. To show the effectiveness of the proposed compliance control method, simulations are performed for two-fingered and three-fingered robot hands.
A new parallel gripping mechanism is proposed in this work. This device has a parallelogramic platform which can be flexibly folded. Therefore, this mechanism not only can be used to grasp an object having irregular s...
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A new parallel gripping mechanism is proposed in this work. This device has a parallelogramic platform which can be flexibly folded. Therefore, this mechanism not only can be used to grasp an object having irregular shape or large volume, but also can be utilized as micro-positioning device after grasping the object. Forward position analysis and platform kinematics are investigated to deal with motion tracking and force control. Pneumatic rotator is employed for actuation and a compact sized, 4/3 way proportional pressure valve is also developed to deal with feedback-based dynamic control. The pressure valve also allows indirect force control by measuring the offset pressure occurring due to contact between the grasped object and the parallel platform. In experimental work, performances of the motion tracking and indirect force control are shown satisfactory.
We consider the feedback stabilization of nonlinear systems. The design methodology is based on a class of iterative methods, which has previously been proposed for the path planning and feedback stabilization of nonh...
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We consider the feedback stabilization of nonlinear systems. The design methodology is based on a class of iterative methods, which has previously been proposed for the path planning and feedback stabilization of nonholonomic systems. We show that this scheme guarantees the closed loop asymptotic stability for a class of nonlinear systems.
An object-oriented modular approach to the engineering of complex robotic systems emphasizes reliability, reusability, ease of development, and user and network interfaces. This modular approach integrates many archit...
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An object-oriented modular approach to the engineering of complex robotic systems emphasizes reliability, reusability, ease of development, and user and network interfaces. This modular approach integrates many architectural principles and computational techniques which support adaptive and learning capability at the local, modular level. The TETROBOT is a modular and reconfigurable robotic system which was developed to demonstrate the reliable performance in a wide variety of task domains through reconfiguration of the same fundamental hardware and software components. Such a modular approach emphasizes the synthesis and integration of engineering modules and takes advantage of object-oriented engineering principles to design for a family of tasks. This paper provides an overview of the TETROBOT modular system and describes three modular systems in other applications domains.
In this paper, active control of flexible structures through utilization of structure mounted sensors and actuators is considered. Specifically, dynamic feedback design utilizing signals from the accelerometer mounted...
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In this paper, active control of flexible structures through utilization of structure mounted sensors and actuators is considered. Specifically, dynamic feedback design utilizing signals from the accelerometer mounted on the structure is discussed. Furthermore, utilization of piezoceramics for sensing and actuation to provide a higher level of control for vibration damping is investigated. The flexible pointing system considered here is the test-bed at the Army Research Development engineeringcenter (ARDEC), which is a scaled-down representation of real-life targetting systems. This setup is also a nice benchmark problem for system identification and different control design philosophies. The approaches advocated here are based on Youla's parametrization of stabilizing controllers, Wiener-Hopf design and decentralized frequency shaping. Modelling aspects for the setup, taking all the structural intricacies into account, are discussed. The preliminary results indicate a significant improvement in performance through utilization of these control schemes.
The problem of transforming a class of linear time-varying continuous time systems into controllable and observable block companion canonical forms is considered. In terms of system block controllability (observabilit...
The problem of transforming a class of linear time-varying continuous time systems into controllable and observable block companion canonical forms is considered. In terms of system block controllability (observability) matrix, this paper generalizes the results of Shieh et al. [3] and provides systematic and straightforward algorithms for obtaining block companion canonical forms. An example is provided to illustrate this transformation technique.
The stability of linear systems subject to possibly fast time-varying uncertainties is analyzed. A necessary and sufficient condition of quadratic stability is derived. An uncertainty stability margin coefficient rho ...
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The stability of linear systems subject to possibly fast time-varying uncertainties is analyzed. A necessary and sufficient condition of quadratic stability is derived. An uncertainty stability margin coefficient rho is introduced to give a quantitative measure of the stability. It is proposed that the uncertain region be approximated by a convex hyperpolyhedron. In this case, the computation of rho becomes a two-level optimization problem, in which the extremum of the inner level can be reached by one of the corners of the hyperpolyhedron.
This paper proposes an alternate approach for adaptive robust control of linear systems with structured, wide-ranging parametric uncertainties. The overall scheme consists of two steps; namely, off-line design of a ro...
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This paper proposes an alternate approach for adaptive robust control of linear systems with structured, wide-ranging parametric uncertainties. The overall scheme consists of two steps; namely, off-line design of a robust observer for the partial states of the system, and design of an on-line adaptive pole placement scheme. It is shown that by using this approach, both direct as well as indirect adaptive pole placement can be achieved. Proofs of stability of the schemes are also given.
The stability of linear systems subject to possibly fast time-varying uncertainties is analyzed. A necessary and sufficient condition for quadratic stability is derived. An uncertainty stability margin coefficient rho...
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The stability of linear systems subject to possibly fast time-varying uncertainties is analyzed. A necessary and sufficient condition for quadratic stability is derived. An uncertainty stability margin coefficient rho is introduced to give a quantitative measure of the stability. It is proposed that the uncertain region be approximated by a convex hyperpolyhedron. In this case, the computation of rho becomes a two-level optimization problem, in which the extremum of the inner level can be reached by one of the corners of the hyperpolyhedron.< >
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