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This paper addresses the problem of designing a control that maximizes the harvested energy of a wave energy converter, in the presence of displacement constraints. The feasible displacement range is split into two segments. In the first segment (the inner segment), an unconstrained optimal control is used. In the outer segment, a constraint control is used. For the unconstraint control in the inner...
A vibration controller based on wavelet neural network (WNN) is designed for jacket-type offshore platforms with time delay. The offshore platform is regarded as a single-degree-of-freedom (SDOF) system while wave forces are irregular disturbances, and we can rebuild them in the context of Morison equation and wave theory. To reduce the vibration, a WNN vibration controller is designed based on a...
The design employs direct drive torque motor to achieve a robot single joint with active compliance based on the impedance model. In order to maximize the torque density, transmission transparency and backdrivability, the joint employs a quasi-direct actuator that a single-stage planetary gear is mounted on the motor's rotor. When robot interacts with environments, it's inevitable to change the stiffness...
This paper presents a robust optimal controller for a Hovering Autonomous Underwater Vehicle (HAUV) in station keeping. The proposed controller does not require added mass, hydrodynamic drag force, and buoyancy force information of the HAUV system. The proposed controller is a time invariant controller which combined optimal control technique and robust filter control technique. The optimal control...
Study of electron transport in nanopillar transistor at 300K shows that elastic vibration is an intrinsic behavior of the device. The frequency observed in the drain-source current is found to agree with the charging frequency. Given a quantum dot of size 10×10×9nm3, the maximum displacement is estimated to be 0.3nm. Once the displacement diminishes to zero, single-electron tunnel becomes the dominating...
In view of the disadvantages of tradition seat suspension comfort and large energy consumption of the semi-active seat, an energy-harvest magnetorheological semi-active seat suspension based on piezoelectric structure is proposed. The three degree of freedom vehicle seat suspension model and the piezoelectric cantilever beam energy-harvest simulink model are established, and the force characteristic...
The buffing process used in the repair polishing of an automotive body surface is carried out manually using skilled workers based on their own experience. However, the number of skilled workers available in the workforce is decreasing owing to the aging population. In addition, the surface quality after the buffing process has been applied is dependent on the proficiency level of the polishing worker...
This paper presents a new variable admittance control scheme for improving physical human-robot interaction. For achieving effective assistance, an intuitive cooperation must be achieved by the human operator, in which the detection of the human inference is required. The proposed controller employs a new algorithm for inferring human intention, i.e., acceleration or deceleration, by monitoring the...
In order to make the buffer play the best damping effect at the end of opening of circuit breaker and spring operating mechanism, so as to ensure the curve of opening end of the circuit breaker be smooth and without a rebound, and to ensure the breaking performance of the circuit breaker, it is necessary to perform jointly modeling and simulating calculations for the buffer and circuit breakers. Based...
When quadrupedal robots execute locomotion, their interactions with the ground surface will make themselves unstable without careful compliance control for each leg. This paper presents a control method which uses a virtual leg compliance with instantaneous reflexes to external disturbance to obtain the self-stabilization for legged robots. Each leg was modeled as two sets of virtual spring and damper...
A passive haptic interface that is inherently safe and stable and can present variable virtual asperity was developed. This interface delivers passive resistance force by switching on and off the damping brake of a DC motor without being driven. We conducted identification experiments for six levels of asperity stimuli to investigate human perceptual properties against passive asperity. Variable asperity...
Superconducting magnetically levitated transportation system has been developed. The electrodynamic suspension is used for levitation and guidance. Results of numerical simulation show that the damping factor of this EDS system is small. Thus the damper coil system is introduced to increase damping against oscillation of the bogie. This damper coil system has effect on decreasing oscillation of the...
This paper discusses numerical experiments by the fast computation method of hydraulic robot dynamics. This paper shows a new proposed model with a special nondmensional representation which is based on the proposed model. The four methods are compared with each other with respect to computation time.
A novel adjustable magnetic liquid damper is designed in this paper which dissipates the vibration energy by viscous flow of magnetic liquid with movement of inertia mass. Firstly, considering the viscosity of magnetic liquid and the size of the damper, the theoretical model of the magnetic mechanical coupling system is established, and the damping force of the damper can be obtained from this model...
Active debris removal and defunct satellites mitigation is one of current hot spots in space research. Based on the deployment process, a new mixed space web is proposed in present paper. Firstly, the Vector Form Intrinsic Finite Element Method and “Kelvin-Voigt” viscoelastic constitution relation are adopted to establish the dynamic model of space web. Then the reliability of the simulation model...
This paper originally applied an optimal sliding mode based optimal composite nonlinear feedback (ISM-CNF) control strategy to the capacitive micromachined ultrasonic transducers (CMUTs) system. It is known that CMUTs system is inherently unstable which results in pull-in phenomenon and sensitive to a small perturbations. Therefore the major problem is to stablize the CMUTS system beyond the pull-in...
This paper designs a vibration controller based on back propagation (BP) neural network for jacket-type offshore platforms with time delay. With an exosystem designed, we can describe the irregular wave forces in the context of Morison equation and wave theory. The original vibration control can be seen as an optimal control problem. This linear discrete-time system is affected by wave forces as external...
This paper describes the methods and experiment protocols for estimation of the human ankle impedance during turning and straight line walking. The ankle impedance of two human subjects during the stance phase of walking in both dorsiflexion plantarflexion (DP) and inversion eversion (IE) were estimated. The impedance was estimated about 8 axes of rotations of the human ankle combining different amounts...
Accurate mathematical models especially accurate hydrodynamic parameters of unmanned underwater vehicles (UUVs) are essential for good control performance. This paper provides a general framework for the hydrodynamic modeling of a small-scale UUV. In place of physical experiments such as captive model tests, a virtual model test and simulation was conducted via commercial computational fluid dynamics...
In this paper, adaptive neural network control for uncertain offshore steel jacket platform with nonlinear self-excited wave force is studied. A sliding mode based adaptive controller is constructed to reduce the oscillation amplitudes of the system. The neural network systems are used to cancel the system uncertainties. Throughout the simulation results we can find that the proposed control method...
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