Negative Input Shaped Commands for Unequal Acceleration and Braking Delays of Actuators

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Yoon-Gyung Sung ◽  
Wan-Shik Jang ◽  
Jae-Yeol Kim
Keyword(s):  
Closed Form Solution ◽  
Industrial Applications ◽  
Step Function ◽  
Form Solution ◽  
Flexible Systems ◽  
Control Performance ◽  
Vector Diagram ◽  
Input Shaper ◽  
Benchmark System ◽  
And Control

A negative input shaped command is presented for flexible systems to reduce the residual oscillation under unequal acceleration and braking delays of actuators that are common issues in industrial applications. Against this nonlinearity, a compensated unit magnitude zero vibration (UMZV) shaper is analytically developed with a phasor vector diagram and a ramp-step function to approximate the dynamic response of the unequal acceleration and braking delays of actuators. A closed-form solution is presented with a benchmark system without sacrificing the generality and simplicity for industrial applications. The robustness and control performance of the exact solution are numerically evaluated and compared with those of an existing negative input shaper in terms of the switch-on time, command interference, and effects of the shaper parameters. The proposed negative input shaped commands are experimentally validated with a mini-bridge crane.

Stability and Imperfections in Quasistatic Viscoplastic Solutions

1990 ◽  
Vol 43 (5S) ◽  
pp. S251-S255 ◽  
Author(s):  
T. Belytschko ◽  
B. Moran ◽  
M. Kulkarni
Keyword(s):  
Strain Field ◽  
Strain Softening ◽  
Fourier Spectrum ◽  
Shear Bands ◽  
Closed Form Solution ◽  
Step Function ◽  
Form Solution ◽  
Viscoplastic Material ◽  
Strain Fields ◽  
The Stability

The effect of imperfections on the structure of shear bands in strain-softening viscoplasticity is studied via a closed form solution. The stability of various solutions is then examined by varying the data through imperfections. It is shown that a step-function imperfection, such as commonly used in finite element solutions, leads to a step-function shear strain field, which is an unstable solution. Arbitrary C0 and C1 imperfections lead to C0 and C1 strain fields, respectively. Fourier analyses show that the imperfection scales the response of the viscoplastic material: the Fourier spectrum of the strain field is strongly influenced by the Fourier spectrum of the imperfection.

DELEGATED MANAGEMENT IN DYNAMIC DUOPOLIES

2010 ◽  
Vol 12 (02) ◽  
pp. 93-114
Author(s):  
VLADIMIR P. PETKOV
Keyword(s):  
Functional Form ◽  
Closed Form Solution ◽  
Industry Structure ◽  
Form Solution ◽  
Linear Quadratic ◽  
Current Effort ◽  
First Mover Advantage ◽  
And Control ◽  
Direct Management ◽  
First Mover

This paper studies the commitment value of delegation in a model of dynamic competition. We argue that separating ownership and control delivers an instantaneous first-mover advantage. Thus, delegation would enable an oligopolistic firm to increase its equilibrium profit relative to direct management. We focus on remuneration strategies that provide managers with intertemporal production incentives: future wages depend on current effort. Their composition and functional form are endogenously determined by the requirement for Markov perfection. For the case of linear-quadratic payoffs, we obtain a closed-form solution for the equilibrium wage strategies which is independent of industry structure.

Fracture behavior of periodically bonded interface of piezoelectric bi-material under compressive–shear loading

2019 ◽  
Vol 24 (10) ◽  
pp. 3216-3230 ◽  
Author(s):  
S Kozinov ◽  
A Sheveleva ◽  
V Loboda
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fracture Behavior ◽  
Compressive Loading ◽  
Closed Form Solution ◽  
Industrial Applications ◽  
Shear Loading ◽  
Form Solution ◽  
Applied Loading

A closed-form solution is constructed for a bi-material consisting of two piezoelectric (or piezoelectric and dielectric) half-planes, which are periodically bonded along the interface and can partially contact along the initially unbonded parts. Under compressive loading, the size of the frictionless contact zone is usually quite large; in some cases the interface is completely closed. Such a situation is frequently observed in industrial applications. Since the periodic bonding of two different materials is extremely widespread, it is very important to study the influence of the mutual material properties of the composite and the applied loading on the size and shape of the opened regions, as well as the stress intensity factor at the bonding points. To formulate the problem, the electromechanical factors are presented through piecewise analytic functions, so that the problem in question is reduced to the combined periodic Dirichlet–Riemann problem, which is solved exactly. The obtained solution provides explicit formulas for the mechanical stresses and displacements along the interface and allows one to find the dependence of the contact zones and the stress intensity factor on the ratio of the bonded parts of the interface to the period for the different values of applied loading and materials.

scholarly journals A Camera Intrinsic Matrix-Free Calibration Method for Laser Triangulation Sensor

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 559
Author(s):  
Xuzhan Chen ◽  
Youping Chen ◽  
Bing Chen ◽  
Zhuo He ◽  
Yunxiu Ma ◽  
...  
Keyword(s):  
Closed Form Solution ◽  
Calibration Method ◽  
Industrial Applications ◽  
Form Solution ◽  
Displacement Measurement ◽  
Necessary Condition ◽  
Laser Triangulation ◽  
Depth Information ◽  
One Dimensional ◽  
Matrix Free

Laser triangulation sensors (LTS) are widely used to acquire depth information in industrial applications. However, the parameters of the components, e.g., the camera, of the off-the-shelf LTS are typically unknown. This makes it difficult to recalibrate the degenerated LTS devices during regular maintenance operations. In this paper, a novel one-dimensional target-based camera intrinsic matrix-free LTS calibration method is proposed. In contrast to conventional methods that calibrate the LTS based on the precise camera intrinsic matrix, we formulate the LTS calibration as an optimization problem taking all parameters of the LTS into account, simultaneously. In this way, many pairs of the camera intrinsic matrix and the equation of the laser plane can be solved and different pairs of parameters are equivalent for displacement measurement. A closed-form solution of the position of the one-dimensional target is proposed to make the parameters of the LTS optimizable. The results of simulations and experiments show that the proposed method can calibrate the LTS without knowing the camera intrinsic matrix. In addition, the proposed approach significantly improves the displacement measurement precision of the LTS after calibration. In conclusion, the proposed method proved that the precise camera intrinsic matrix is not the necessary condition for LTS displacement measurement.

Thermal Management Simulation of Lithium Ion Batteries for EV/HEV

2013 ◽  
Vol 457-458 ◽  
pp. 350-353
Author(s):  
Fofana Gaoussou Hadia ◽  
You Tong Zhang
Keyword(s):  
Lithium Ion Batteries ◽  
Heat Generation ◽  
Fundamental Problem ◽  
Three Dimensional ◽  
Closed Form Solution ◽  
Lithium Ion ◽  
Form Solution ◽  
Mechanism Analysis ◽  
And Control ◽  
The Impact

In this paper, we propose a three-dimensional analytical model based on Greens Function to investigate the Impact of temperature rising on simple lithium-ion batteries and control the heat generation during charge/discharge of battery operation. The modeling is based on heat-transform mechanism analysis method that gives a closed-form solution for the fundamental problem of heat conduction in battery cores with orthotropic thermal conductivities. The method uses a simple lithium-ion battery examined, considered the ambient temperature and initial temperature as 25°C, subjected to transient heat generation in various convective cooling boundary conditions at its surfaces.

scholarly journals ANALYTICAL EXPRESSION FOR UNCERTAINTY PROPAGATION OF AERIAL COOPERATIVE NAVIGATION

Aviation ◽  
2021 ◽  
Vol 25 (1) ◽  
pp. 10-21
Author(s):  
Ali Faghihinia ◽  
M. A. Amiri Atashgah ◽  
S. M. Mehdi Dehghan
Keyword(s):  
Growth Rate ◽  
Uncertainty Propagation ◽  
Closed Form Solution ◽  
Form Solution ◽  
Position Error ◽  
Measurement Unit ◽  
Propagation Of Uncertainty ◽  
Cooperative Navigation ◽  
Noise Characteristics ◽  
And Control

In this paper, the propagation of uncertainty in a cooperative navigation algorithm (CNA) for a group of flying robots (FRs) is investigated. Each FR is equipped with an inertial measurement unit (IMU) and range-bearing sensors to measure the relative distance and bearing angles between the agents. In this regard, an extended Kalman filter (EKF) is implemented to estimate the position and rotation angles of all the agents. For further studies, a relaxed analytical performance index through a closed-form solution is derived. Moreover, the effects of the sensors noise covariance and the number of FRs on the growth rate of the position error covariance is investigated. Analytically, it is shown that the covariance of position error in the vehicles equipped with the IMU is proportional to the cube of time. However, the growth rate of the navigation error is, considerably more rapid compared to a mobile robot group. Furthermore, the covariance of position error is independent of the path and noise resulting from the relative position measurements. Further, it merely depends on both the size of the group and noise characteristics of the accelerometers. Lastly, the analytical results are validated through comprehensive Guidance, Navigation, and Control (GNC) in-the-loop simulations.

scholarly journals Deflection Reduction Shaping Commands with Asymmetric First-Order Actuators

2019 ◽  
Vol 9 (19) ◽  
pp. 3982
Author(s):  
Yoon-Gyung Sung ◽  
Chang-Lae Kim
Keyword(s):  
Flexible Structures ◽  
Closed Form Solution ◽  
Form Solution ◽  
Real Time Control ◽  
Pendulum System ◽  
Command Shaping ◽  
First Order ◽  
Time Control ◽  
Input Shaper ◽  
Vector Approach

In this paper, two approaches for generating deflection reduction shaping commands are proposed to reduce the transient and residual deflections of flexible systems subject to asymmetric first-order actuators. The commands are limited-state in that they consist of two positive actuations of different magnitudes and one negative actuation, similar to on-off-on commands. Standard on–off commands that are commonly used in robots, cranes, and spacecrafts can degrade the control performance of conventional input-shaped commands and cause detrimental damage resulting from large transient deflections of flexible structures due to asymmetric first-order actuators. Therefore, to cope with the performance degradation resulting from the effects of first-order actuators, an approximated closed-form solution and a numerically optimized approach for deflection reduction shaping commands are presented with an exponential function, final impulse magnitude modification of an input shaper is determined by a transient deflection constraint and a phasor vector approach. The performance assessment showed that the approximated analytical approach has an advantage in real-time control applications. The characteristics of the proposed deflection reduction shaping commands are analyzed with respect to system parameters, deflection reduction ratios, and actuator time constants. The proposed command shaping techniques are numerically evaluated using a pendulum system and are experimentally validated on a mini-bridge crane.

Analysis and Control of an Actuation-Redundant Parallel Mechanism Requiring Synchronization

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
Fengfeng (Jeff) Xi ◽  
Amin Moosavian ◽  
Gabriel H. Campos ◽  
Upasana (Sana) Choudhuri ◽  
Cong Zhu (John) Sun ◽  
...  
Keyword(s):  
Parallel Mechanism ◽  
Closed Form Solution ◽  
Form Solution ◽  
Force Balance ◽  
End Effector ◽  
Velocity Relationship ◽  
Space Limitation ◽  
And Control ◽  
Force Profiles ◽  
Force Relationship

Abstract Presented in this paper is a method for analysis and control of an actuation-redundant parallel mechanism requiring synchronization. The said mechanism is made up of two branches that are connected to drive a common end-effector with only one degree-of-freedom of motion. The two actuators must share the load exerted on the common end-effector during motion. The underlying problem is to synchronize the motion of the two actuators while balancing the forces on them so that the entire mechanism can move smoothly under the applied load on the end-effector. Due to the space limitation, the two branches are geometrically different leading to opposite force profiles for the two actuators. The proposed method combines the mechanism kinematics with force analysis. First, a closed-form solution is derived that relates the actuator strokes to the rotation angle of the end-effector. Second, a velocity relationship is obtained to relate the actuator velocities to the angular velocity of the end-effector. Third, a force relationship is established relating the actuator loads to the external load. Fourth, a control strategy is designed to synchronize the motion of the two actuators while maintaining the force balance between them to avoid the problem of motion mismatching and force fighting that could lead to the failure of the mechanism. A prototype was built and tested with the proposed method, which is also presented in this paper.

Weld Process Modeling, Monitoring, Teaching, and Control using Artificial Neural Networks: Improving Navy and Commercial Shipbuilding for the Future

2013 ◽  
Author(s):  
Jerald E. Jones ◽  
Valerie L. Rhoades ◽  
Mark D. Mann
Keyword(s):  
Neural Networks ◽  
Real Time ◽  
Closed Form Solution ◽  
Welding Process ◽  
Form Solution ◽  
Monitoring And Control ◽  
Element Analysis ◽  
Line Planning ◽  
Artificial Neural ◽  
And Control

Metal melting and solidification is a physical process which is described by a class of differential equations which have no closed form solution – it is known in Classical Mathematics as the “Stephan Problem”. The iterative methods used by numerical analyses techniques, such as Finite Element Analysis, are far too slow to be effective for process optimization and control. A DARPA Program a decade ago concentrated on flexible manufacturing – basically, robots that program themselves, depend heavily on sensors to be “smart” about their actions and decisions, and perform quality control with little, if any, human involvement. In the DARPA Flexible Automation program, a group of Ph.D. Scientists and Engineers, began applying a new Artificial Neural Network technology, called P/NA3. Today, Neural Networks produced using the P/NA3 technology are accurate and fast so that they can be run in real-time during welding or, embedded into specialized algorithms, to optimize the welding process. This technology enables the “off-line” planning of robotic welds, and real-time quality monitoring and control.

Gravity and Conduction Driven Melting in a Sphere

1986 ◽  
Vol 87 ◽  
Author(s):  
P A. Bahrami ◽  
T. G. Wang
Keyword(s):  
Phase Change ◽  
Closed Form Solution ◽  
Melting Process ◽  
Step Function ◽  
Form Solution ◽  
Film Condensation ◽  
Theoretical Point ◽  
Void Space ◽  
Free Expansion ◽  
Interface Position

AbstractThe fundamental processes of melting, the well known Stefan and Neumann problems, have been of great interest from a theoretical point of view as well as for their wide applications. The yet unmolten part of the material undergoing phase change within spherical containments is generally presumed to remain stationary, an unlikely occurrence in practice. The differing densities of the liquid and the solid may readily cause a force imbalance on the solid in gravitational and perhaps microgravitational environments, thereby moving the solid away from the center. In the present work, an approach related to the theories of lubrication and film condensation was employed and an approximate closed-form solution of melting within spheres was obtained. It was shown that a group of dimensionless parameters containing, Prandtl, Archimedes and Stefan numbers describes the melting process. Fundamental heat transfer experiments were also performed on the melting of a phase-change medium in a spherical shell. Free expansion of the medium into a void space within the sphere was permitted. A step function temperature jump on the outer shell wall was imposed and the timewise evolution of the melting process and the position of the solid-liquid interface was photographically recorded. Numerical integration of the interface position data yielded information about the melted mass and the energy of melting that support the theory.

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