scholarly journals Adaptive Feedforward Control of a Pressure Compensated Differential Cylinder

2020 ◽  
Vol 10 (21) ◽  
pp. 7847
Author(s):  
Konrad Johan Jensen ◽  
Morten Kjeld Ebbesen ◽  
Michael Rygaard Hansen
Keyword(s):  
Control System ◽  
Root Mean Square ◽  
Motion Control ◽  
Experimental Verification ◽  
Feedforward Control ◽  
Position Error ◽  
Mean Square ◽  
Model Uncertainties ◽  
Feedforward Controller ◽  
Adaptive Feedforward

This paper presents the design, simulation and experimental verification of adaptive feedforward motion control for a hydraulic differential cylinder. The proposed solution is implemented on a hydraulic loader crane. Based on common adaptation methods, a typical electro-hydraulic motion control system has been extended with a novel adaptive feedforward controller that has two separate feedforward states, i.e, one for each direction of motion. Simulations show convergence of the feedforward states, as well as 23% reduction in root mean square (RMS) cylinder position error compared to a fixed gain feedforward controller. The experiments show an even more pronounced advantage of the proposed controller, with an 80% reduction in RMS cylinder position error, and that the separate feedforward states are able to adapt to model uncertainties in both directions of motion.

Synchronization of Two Motion Control Axes Under Adaptive Feedforward Control

1992 ◽  
Vol 114 (2) ◽  
pp. 196-203 ◽  
Author(s):  
Masayoshi Tomizuka ◽  
Jwu-Sheng Hu ◽  
Tsu-Chih Chiu ◽  
Takuya Kamano
Keyword(s):  
Motion Control ◽  
Time Domain ◽  
Adaptive Systems ◽  
Feedforward Control ◽  
Synchronization Error ◽  
Adaptive Synchronization ◽  
Motion Error ◽  
Feedforward Controller ◽  
The Difference ◽  
Adaptive Feedforward

In this paper, motion synchronization of two d-c motors, or motion control axes, under adaptive feedforward control is considered. The adaptive feedforward control system for each axis consists of a proportional feedback controller, an adaptive disturbance compensator and an adaptive feedforward controller. If the two adaptive systems are left uncoupled, a disturbance input applied to one of the two axes will cause a motion error in the disturbed axis only, and the error becomes the synchronization error. To achieve a better synchronization, a coupling controller, which responds to the synchronization error, i.e., the difference between the two motion errors, is introduced. In this case, when a disturbance input is applied to one axis, the motion errors appear in the undisturbed axis as well as in the disturbed axis. The motion error in the undisturbed axis is introduced by the coupling controller and the adaptive feedforward controller. The adaptive synchronization problem is formulated and analyzed in the continuous time domain first, and then in the discrete time domain. Stability conditions are obtained. Effectiveness of the adaptive synchronization controller is demonstrated by simulation.

Adaptive Feedforward Vibration Control of Flexible Structure With Discrete Sliding Mode Controller

2006 ◽  
Author(s):  
J. Fei
Keyword(s):  
Control System ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Flexible Beam ◽  
Sliding Mode Controller ◽  
Control Scheme ◽  
Feedforward Controller ◽  
Adaptive Lms ◽  
Adaptive Feedforward

This paper presents an adaptive feedforward control scheme using the least mean square (LMS) algorithm combined with sliding mode control for a flexible beam using piezoceramic actuator. A finite element model of the dynamic response of flexible beam system with PZT patches is derived and analyzed. Implementation of an adaptive LMS feedforward controller has the advantages of inherent stability and simplicity in design. The proposed adaptive LMS feedforward control system maintains the basic structure of the adaptive feedforward controller, but incorporates reference model in the system. Discrete sliding mode controller is added in the feedback loop to enhance the robustness of control system subjected to the variation of system parameters and external disturbances. Simulation results from flexible beam model verify the effectiveness of the proposed adaptive LMS feedforward with sliding mode control scheme and good disturbance rejection properties.

scholarly journals Robust Position Control of an Over-actuated Underwater Vehicle under Model Uncertainties and Ocean Current Effects Using Dynamic Sliding Mode Surface and Optimal Allocation Control

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 747
Author(s):  
Mai The Vu ◽  
Tat-Hien Le ◽  
Ha Le Nhu Ngoc Thanh ◽  
Tuan-Tu Huynh ◽  
Mien Van ◽  
...  
Keyword(s):  
Control System ◽  
Motion Control ◽  
Optimal Allocation ◽  
Position Control ◽  
Sliding Mode ◽  
Underwater Vehicle ◽  
Ocean Current ◽  
Model Uncertainties ◽  
Control Module ◽  
Dynamic Sliding Mode

Underwater vehicles (UVs) are subjected to various environmental disturbances due to ocean currents, propulsion systems, and un-modeled disturbances. In practice, it is very challenging to design a control system to maintain UVs stayed at the desired static position permanently under these conditions. Therefore, in this study, a nonlinear dynamics and robust positioning control of the over-actuated autonomous underwater vehicle (AUV) under the effects of ocean current and model uncertainties are presented. First, a motion equation of the over-actuated AUV under the effects of ocean current disturbances is established, and a trajectory generation of the over-actuated AUV heading angle is constructed based on the line of sight (LOS) algorithm. Second, a dynamic positioning (DP) control system based on motion control and an allocation control is proposed. For this, motion control of the over-actuated AUV based on the dynamic sliding mode control (DSMC) theory is adopted to improve the system robustness under the effects of the ocean current and model uncertainties. In addition, the stability of the system is proved based on Lyapunov criteria. Then, using the generalized forces generated from the motion control module, two different methods for optimal allocation control module: the least square (LS) method and quadratic programming (QP) method are developed to distribute a proper thrust to each thruster of the over-actuated AUV. Simulation studies are conducted to examine the effectiveness and robustness of the proposed DP controller. The results show that the proposed DP controller using the QP algorithm provides higher stability with smaller steady-state error and stronger robustness.

scholarly journals Consistency of the Empirical Distributions of Navigation Positioning System Errors with Theoretical Distributions—Comparative Analysis of the DGPS and EGNOS Systems in the Years 2006 and 2014

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 31
Author(s):  
Mariusz Specht
Keyword(s):  
Normal Distribution ◽  
Root Mean Square ◽  
Statistical Tests ◽  
Position Error ◽  
Positioning System ◽  
Navigation Systems ◽  
Mean Square ◽  
Positioning Systems ◽  
Position Errors ◽  
System Errors

Positioning systems are used to determine position coordinates in navigation (air, land and marine). The accuracy of an object’s position is described by the position error and a statistical analysis can determine its measures, which usually include: Root Mean Square (RMS), twice the Distance Root Mean Square (2DRMS), Circular Error Probable (CEP) and Spherical Probable Error (SEP). It is commonly assumed in navigation that position errors are random and that their distribution are consistent with the normal distribution. This assumption is based on the popularity of the Gauss distribution in science, the simplicity of calculating RMS values for 68% and 95% probabilities, as well as the intuitive perception of randomness in the statistics which this distribution reflects. It should be noted, however, that the necessary conditions for a random variable to be normally distributed include the independence of measurements and identical conditions of their realisation, which is not the case in the iterative method of determining successive positions, the filtration of coordinates or the dependence of the position error on meteorological conditions. In the preface to this publication, examples are provided which indicate that position errors in some navigation systems may not be consistent with the normal distribution. The subsequent section describes basic statistical tests for assessing the fit between the empirical and theoretical distributions (Anderson-Darling, chi-square and Kolmogorov-Smirnov). Next, statistical tests of the position error distributions of very long Differential Global Positioning System (DGPS) and European Geostationary Navigation Overlay Service (EGNOS) campaigns from different years (2006 and 2014) were performed with the number of measurements per session being 900’000 fixes. In addition, the paper discusses selected statistical distributions that fit the empirical measurement results better than the normal distribution. Research has shown that normal distribution is not the optimal statistical distribution to describe position errors of navigation systems. The distributions that describe navigation positioning system errors more accurately include: beta, gamma, logistic and lognormal distributions.

Grasp Transfer Control Using Cartesian Coordinate Two-Link Robot Arm with Prototype Robot Hand Consisting of Stepping Motors, Gears and Plate Springs

2008 ◽  
Vol 2 (5) ◽  
pp. 360-367
Author(s):  
Ping Han ◽  
◽  
Hiroyuki Kojima ◽  
Lingfang Huang ◽  
Saputra Meruadi ◽  
...  
Keyword(s):  
Control System ◽  
Numerical Simulations ◽  
Permanent Magnet ◽  
Motion Control ◽  
Force Control ◽  
Feedforward Control ◽  
Robot Hand ◽  
Robot Arm ◽  
Grasp Force ◽  
Cartesian Coordinate

In this study, the grasp transfer control system by a Cartesian coordinate two-link robot arm with a prototype robot hand is presented. The prototype robot hand consists of permanent-magnet-type stepping motors, gears and plate springs. The grasp force control of the robot hand is performed by a feedforward control of the stepping motors based on the dimension of a grasped object. The Cartesian coordinate two-link robot arm consists of ball screws and hybrid stepping motors. Then the numerical simulations and experiments of the grasp transfer control have been carried out, and it is confirmed that the grasp transfer control could be successfully performed, and the grasp force could be accurately controlled among the motion control of the Cartesian coordinate two-link robot arm.

scholarly journals Adaptive Feedforward Control for Gust-Induced Aeroelastic Vibrations

Aerospace ◽  
2018 ◽  
Vol 5 (3) ◽  
pp. 86 ◽  
Author(s):  
Yongzhi Wang ◽  
Andrea Da Ronch ◽  
Maryam Ghandchi Tehrani
Keyword(s):  
Feedforward Control ◽  
Single Input Single Output ◽  
Output Controller ◽  
Single Output ◽  
Aeroelastic Model ◽  
Feedforward Controller ◽  
The Time Domain ◽  
Adaptive Feedforward ◽  
The Impact ◽  
Aeroelastic Vibrations

This paper demonstrates the implementation of an adaptive feedforward controller to reduce structural vibrations on a wing typical section. The aeroelastic model includes a structural nonlinearity, which is modelled in a polynomial form. Aeroelastic vibrations are induced by several gusts and atmospheric turbulence, including the discrete “one-minus-cosine” and a notably good approximation in the time-domain to the von Kármán spectrum. The control strategy based on the adaptive feedforward controller has several advantages compared to the standard feedback controller. The controller gains, which are updated in real-time during the gust encounter, are found solving a minimization problem using the finite impulse responses as basis functions. To make progress with the application in aeroelasticity, a single-input single-output controller is designed measuring the wing torsional deformation. For both deterministic and random atmospheric shapes, the controller was found successful in alleviating the aeroelastic vibrations. The impact of the control action on the unmeasured structural modes was found minimal.

scholarly journals DESIGN AND FABRICATION OF RUNNING CHEETAH MECHANICAL TOY USING FOUR-BAR LINKAGE

2020 ◽  
Vol 5 (4) ◽  
pp. 53-60
Author(s):  
Adimas Wicaksana
Keyword(s):  
Root Mean Square ◽  
Closed Loop ◽  
Design Method ◽  
Position Error ◽  
Prototype Model ◽  
Mean Square ◽  
Four Bar Linkage ◽  
Novel Design

Four-bar is the simplest planar 1-DOF closed loop linkage. It has been studied for centuries for its versatility and simplicity. In this paper a novel design method to obtain a four-bar linkage given a path and its endpoints will be presented. This method will then be applied to a case study of making a model that produces a specified movement based on reference animation. The mechanism obtained had an average root-mean-square of position error of roughly 14.3 pixels for front leg and 25.9 pixels for hind leg. This number is quite small compared to the perimeter of the traced path, which are 530 pixels and 617 pixels for front leg and hind leg respectively. A prototype model of the designed mechanism was fabricated to verify its manufacturing viability and to confirm the correctness of the path generated.

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