Model-Based Optimal Control for Underwater Robotics

2010 ◽  
Author(s):  
Yingfeng Ji ◽  
Ryoichi S. Amano ◽  
Ronald A. Perez
Keyword(s):  
High Speed ◽  
Linear Control ◽  
Design Stage ◽  
Underwater Robotics ◽  
Fluid Forces ◽  
Nonlinear Properties ◽  
Highly Nonlinear ◽  
Control Technologies ◽  
The One ◽  
External Forces

It is always one of the most challenging problems to control an underwater robotics due to the complex external forces in an underwater environment. It is difficult to obtain an ideal control performance using linear control technologies due to highly nonlinear properties of system. A valid method of linearization for nonlinear system is provided in this study. Based on this linearized system, the linear control theories were therefore employed for the tracking control of underwater robotics. The panning and tilting motions of this underwater robotics can basically track two given sinusoidal references based on the simulation results. In order to achieve a high-speed manipulation of this underwater robotics, fluid forces have to be considered and modeled. A computational fluid dynamics (CFD) technology is adopted in order to obtain more precise hydrodynamic models for simulation at the design stage. Two torque models that represent the degree of freedoms (DOFs) of panning and tilting respectively have been developed using the CFD software. The dynamic model of this robotics used in this paper is the one by Ji, et al [1].

A CAD Package for High-Speed Cam Design Based on Direct Multiple Shooting Optimal Control Techniques

2004 ◽  
Author(s):  
Sebastian Mennicke ◽  
Richard W. Longman ◽  
Meng-Sang Chew ◽  
Hans Georg Bock
Keyword(s):  
Optimal Control ◽  
High Speed ◽  
Optimality Criteria ◽  
Iterative Refinement ◽  
Valve Train ◽  
Design Stage ◽  
Multiple Shooting ◽  
Cam Design ◽  
Trade Offs ◽  
Highly Nonlinear

High-speed automotive valve train design requires realistic models of the valve train. However, this frequently results in highly nonlinear systems with discontinuities and constraints. Optimality criteria and trade-offs for the designs are frequently performed through a process of simulation and iterative refinement. This paper presents CamOE, a cam design optimization package based on direct multiple shooting optimal control theory, incorporating structured sequential quadratic programming. The code allows the designer to incorporate the constraints of importance and to consider and synthesize appropriate optimality criteria. This allows him or her to synthesize the cam profile at the design stage without resorting to a tedious trial-and-error design process. This paper presents CamOE as a software environment that permits rapid feedback to the designer through the process of numerical experiments in specifying criteria and constraints on the automotive valve train.

scholarly journals Spin-orbit torque–driven propagating spin waves

2019 ◽  
Vol 5 (9) ◽  
pp. eaax8467 ◽  
Author(s):  
H. Fulara ◽  
M. Zahedinejad ◽  
R. Khymyn ◽  
A. A. Awad ◽  
S. Muralidhar ◽  
...  
Keyword(s):  
High Speed ◽  
Data Transfer ◽  
Dipolar Coupling ◽  
Perpendicular Magnetic Anisotropy ◽  
Cmos Technology ◽  
Spin Orbit ◽  
Neuromorphic Computing ◽  
Mutual Synchronization ◽  
Nonlinear Properties ◽  
Highly Nonlinear

Spin-orbit torque (SOT) can drive sustained spin wave (SW) auto-oscillations in a class of emerging microwave devices known as spin Hall nano-oscillators (SHNOs), which have highly nonlinear properties governing robust mutual synchronization at frequencies directly amenable to high-speed neuromorphic computing. However, all demonstrations have relied on localized SW modes interacting through dipolar coupling and/or direct exchange. As nanomagnonics requires propagating SWs for data transfer and additional computational functionality can be achieved using SW interference, SOT-driven propagating SWs would be highly advantageous. Here, we demonstrate how perpendicular magnetic anisotropy can raise the frequency of SOT-driven auto-oscillations in magnetic nanoconstrictions well above the SW gap, resulting in the efficient generation of field and current tunable propagating SWs. Our demonstration greatly extends the functionality and design freedom of SHNOs, enabling long-range SOT-driven SW propagation for nanomagnonics, SW logic, and neuromorphic computing, directly compatible with CMOS technology.

scholarly journals SIMULATION MODELING OF DESTRUCTION OF TYPICAL FASTENING ELEMENTS FOR DETONATION

2020 ◽  
Vol 11 (87) ◽  
Author(s):  
Marina Chernobryvko ◽  
◽  
Svitlana Svetlichna ◽  
Keyword(s):  
Composite Structures ◽  
High Speed ◽  
Dynamic Strength ◽  
Experimental Tests ◽  
Correct Choice ◽  
Bolted Joints ◽  
Design Stage ◽  
Design Work ◽  
Bolted Connection ◽  
Nonlinear Properties

A number of precautions are used to prevent injuries to people and industrial equipment during accidents at chemical plants. One of them is based on the use of protective containers for the storage of explosives. A typical container consists of a main structure and a lid of the loading hole. This cover is fixed to the container with fasteners based on bolted connections. To ensure the normative strength of such a connection at the design stage, an analysis of its dynamic strength is performed and the critical loads that cause the destruction of the structure are determined. To reduce the cost of design work, it is advisable to replace a number of experimental tests with numerical studies and simulate the process of destruction. Therefore, the development of methods for numerical analysis of dynamic strength and integrity of typical fasteners based on bolted joints is an urgent problem. Simulation of the destruction of composite structures based on bolted joints should adequately reflect the complex of mechanical loads. First, it is a static load due to the assembly of the bolted connection. Secondly, it is high-speed dynamic loads due to the action of a detonation shock wave. For mathematical modeling of such processes, it is necessary to take into account the influence of the load speed on the mechanical properties of metals in the bolted joint. An important role in modeling the destruction process is played by the correct choice of the criterion of destruction of the structural material. According to the analysis of previous studies, the criterion of maximum plastic deformation was chosen. For the numerical implementation of the developed mathematical model of high-speed deformation and destruction of the folded fastening structure on the basis of bolted connection taking into account nonlinear properties of mechanical characteristics of materials and influence of previous loadings during assembly of a design the finite element method is chosen. The application of the proposed technique at the design stage of protective containers allows to reduce the number of experimental tests and thus reduce the development time and to reduce its cost.

Reliability analysis of a tendon-driven actuation for soft robots

2020 ◽  
pp. 027836492090715
Author(s):  
Useok Jeong ◽  
Keunsu Kim ◽  
Sang-Hun Kim ◽  
Hyunhee Choi ◽  
Byeng Dong Youn ◽  
...  
Keyword(s):  
Reliability Analysis ◽  
Domain Knowledge ◽  
Design Stage ◽  
Concept Design ◽  
Force Transmission ◽  
Soft Robots ◽  
Nonlinear Properties ◽  
Highly Nonlinear ◽  
Life Model ◽  
Robotic Devices

The reliability of soft robotic devices will be the bottleneck that slows their commercialization. In particular, fatigue failure issues are a major concern. Thus, reliability should be taken into account from the earliest stages of development. However, to date, there have been no attempts to analyze the reliability of soft robotic devices in a systematic manner. When soft robots are employed to force transmission applications, reliability is typically a dominant issue, since soft robotic structures are constructed with soft material components; these materials have highly nonlinear properties that arise due to the large distribution in the material properties. Furthermore, reliability should be analyzed from the robot’s system down to the components using domain knowledge about the system; this requires a systematic approach. This study presents a framework for reliability analysis of soft robotic devices taking into account a probability distribution that has not been considered before and examines a case study of a tendon-driven soft robot. This study focuses specifically on the (a) concept design process, (b) lifetime analysis process, and (c) design and optimization process. A life model that considers distribution is proposed using accelerated life testing based on analysis of the failure mechanism of the tendon-driven system. The tensile stress of the wire was varied during the experiment with different bend angles and output tension. The result was validated with different stress levels using a testbed to simulate an actual application. The proposed reliability analysis methodology could be applied to other soft robotic systems, such as pneumatic actuators, to improve the reliability-related properties during the robot design stage, and the life model can be used to estimate the device lifetime under various stress conditions.

scholarly journals Reliability-Oriented Design of Inverter-Fed Low-Voltage Electrical Machines: Potential Solutions

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4144
Author(s):  
Yatai Ji ◽  
Paolo Giangrande ◽  
Vincenzo Madonna ◽  
Weiduo Zhao ◽  
Michael Galea
Keyword(s):  
Power Density ◽  
High Speed ◽  
High Performance ◽  
Low Voltage ◽  
Electrical Machines ◽  
Design Stage ◽  
Switching Frequency ◽  
Special Focus ◽  
Electrical Machine ◽  
Engineering Approach

Transportation electrification has kept pushing low-voltage inverter-fed electrical machines to reach a higher power density while guaranteeing appropriate reliability levels. Methods commonly adopted to boost power density (i.e., higher current density, faster switching frequency for high speed, and higher DC link voltage) will unavoidably increase the stress to the insulation system which leads to a decrease in reliability. Thus, a trade-off is required between power density and reliability during the machine design. Currently, it is a challenging task to evaluate reliability during the design stage and the over-engineering approach is applied. To solve this problem, physics of failure (POF) is introduced and its feasibility for electrical machine (EM) design is discussed through reviewing past work on insulation investigation. Then the special focus is given to partial discharge (PD) whose occurrence means the end-of-life of low-voltage EMs. The PD-free design methodology based on understanding the physics of PD is presented to substitute the over-engineering approach. Finally, a comprehensive reliability-oriented design (ROD) approach adopting POF and PD-free design strategy is given as a potential solution for reliable and high-performance inverter-fed low-voltage EM design.

Highly nonlinear polarization maintaining dispersion compensating fiber for high-speed transmission system

2013 ◽  
Vol 52 (11) ◽  
pp. 116112 ◽  
Author(s):  
Md. Imran Hasan ◽  
Md. Samiul Habib ◽  
Md. Selim Habib ◽  
S. M. Abdur Razzak
Keyword(s):  
High Speed ◽  
Transmission System ◽  
Nonlinear Polarization ◽  
Highly Nonlinear ◽  
Polarization Maintaining

Starting Processes in Electric Drive of a Passenger Elevator

2021 ◽  
Vol 1 (1) ◽  
pp. 40-49
Author(s):  
S. Rachev ◽  
K. Dimitrova ◽  
D. Koeva ◽  
L. Dimitrov
Keyword(s):  
Coordinate System ◽  
Induction Motor ◽  
Electric Drive ◽  
High Speed ◽  
Induction Motors ◽  
Dynamic Loads ◽  
Design Stage ◽  
Motor Drive ◽  
Induction Motor Drive ◽  
Electric Induction

During the operation of electric induction motors used to drive passenger elevators, electro-mechanical transient processes occur, which can cause unacceptable dynamic loads and vibrations. In this regard, research is needed both at the design stage and for operating elevator systems to determine the arising impact currents and torques, in order to propose solutions for their limitation within pre-set limits. Paper deals with starting processes in a two-speed induction motor drive of a passenger elevator. The equations for the voltages of the induction motor are presented in relative units in a coordinate system rotating at a synchronous speed. The values have been obtained for the torques, the rotational frequencies and the currents when starting at a high speed and passing from high to low speed.

Estimating Critical Speeds of Stepped Shafts with Flexible Bearings

1971 ◽  
Vol 8 (03) ◽  
pp. 327-333
Author(s):  
R. H. Salzman
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Design Stage ◽  
Normal Range ◽  
Critical Speeds ◽  
Stepped Shaft ◽  
Bearing Stiffness ◽  
Variable Support ◽  
Method Show ◽  
Good Agreement

This paper presents a semi-graphical approach for finding the first critical speed of a stepped shaft with finite bearing stiffness. The method is particularly applicable to high-speed turbine rotors with journal bearings. Using Rayleigh's Method and the exact solution for whirling of a uniform shaft with variable support stiffness, estimates of the lowest critical speed are easily obtained which are useful in the design stage. First critical speeds determined by this method show good agreement with values computed by the Prohl Method for the normal range of bearing stiffness. A criterion is also established for determining if the criticals are "bearing critical speeds" or "bending critical speeds," which is of importance in design. Discusser E. G. Baker

Aeroelastic Problems in connection with High-Speed Flight

1956 ◽  
Vol 60 (547) ◽  
pp. 459-475 ◽  
Author(s):  
E. G. Broadbent
Keyword(s):  
Mach Number ◽  
High Speed ◽  
The Other ◽  
Control Surface ◽  
The Past ◽  
Other Hand ◽  
Aerodynamic Derivatives ◽  
Mach Numbers ◽  
The One

SummaryA review is given of developments in the field of aeroelasticity during the past ten years. The effect of steadily increasing Mach number has been two-fold: on the one hand the aerodynamic derivatives have changed, and in some cases brought new problems, and on the other hand the design for higher Mach numbers has led to thinner aerofoils and more slender fuselages for which the required stiffness is more difficult to provide. Both these aspects are discussed, and various methods of attack on the problems are considered. The relative merits of stiffness, damping and massbalance for the prevention of control surface flutter are discussed. A brief mention is made of the recent problems of damage from jet efflux and of the possible aeroelastic effects of kinetic heating.

Effect of Different Geometrical Inlet Pipes on a High Speed Centrifugal Compressor

2013 ◽  
Author(s):  
Ce Yang ◽  
Ben Zhao ◽  
C. C. Ma ◽  
Dazhong Lao ◽  
Mi Zhou
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Ratio ◽  
Inlet Pipe ◽  
Unsteady Pressure ◽  
Bent Pipe ◽  
Low Mass ◽  
Compressor Performance ◽  
Spectral Frequency ◽  
The One

Two different inlet configurations, including a straight pipe and a bent pipe, were experimentally tested and numerically simulated using a high-speed, low-mass flow centrifugal compressor. The pressure ratios of the compressor with the two inlet configurations were tested and then compared to illustrate the effect of the bent inlet pipe on the compressor. Furthermore, different circumferential positions of the bent inlet pipe relative to the volute are discussed for two purposes. One purpose is to describe the changes in the compressor performance that result from altering the circumferential position of the bent inlet pipe relative to the volute. This change in performance may be the so-called clocking effect, and its mechanism is different from the one in multistage turbomachinery. The other purpose is to investigate the unsteady flow for different matching states of the bent inlet pipe and volute. Thus, the frequency spectrum of unsteady pressure fluctuation was applied to analyze the aerodynamic response. Compared with the straight inlet pipe, the experimental results show that the pressure ratio is modulated and that the choke point is shifted in the bent inlet pipe. Similarly, the pressure ratio can be influenced by altering the circumferential position of the bent inlet pipe relative to the volute, which may have an effect on the unsteady pressure in the rotor section. Therefore, the magnitude of interest spectral frequency is significantly changed by clocking the bent inlet pipe.

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