scholarly journals Synchronization Control of a Dual-Cylinder Lifting Gantry of Segment Erector in Shield Tunneling Machine under Unbalance Loads

Machines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 152
Author(s):  
Litong Lyu ◽  
Xiao Liang ◽  
Jingbo Guo
Keyword(s):  
Motion Tracking ◽  
Adaptive Robust Control ◽  
Synchronization Control ◽  
Small Range ◽  
Linear Motion ◽  
Shield Tunneling ◽  
Rotational Angle ◽  
High Level ◽  
Unbalanced Loads ◽  
Segment Erector

Segment assembling is one of the principle processes during tunnel construction using shield tunneling machines. The segment erector is a robotic manipulator powered by a hydraulic system to assemble prefabricated concrete segments onto the excavated tunnel surface. Nowadays, automation of the segment erector has become one of the definite developing trends to further improve the efficiency and safety during construction; thus, closed-loop motion control is an essential technology. Within the segment erector, the lifting gantry is driven by dual cylinders to lift heavy segments in the radial direction. Different from the dual-cylinder mechanism used in other machines such as forklifts, the lifting gantry usually works at an inclined angle, leading to unbalanced loads on the two sides. Although strong guide rails are applied to ensure synchronization, the gantry still occasionally suffers from chattering, “pull-and-drag”, or even being stuck in practice. Therefore, precise motion tracking control as well as high-level synchronization of the dual cylinders have become essential for the lifting gantry. In this study, a complete dynamics model of the dual-cylinder lifting gantry is constructed, considering the linear motion as well as the additional rotational motion of the crossbeam, which reveals the essence of poor synchronization. Then, a two-level synchronization control scheme is synthesized. The thrust allocation is designed to coordinate the dual cylinders and keep the rotational angle of the crossbeam within a small range. The motion tracking controller is designed based on the adaptive robust control theory to guarantee the linear motion tracking precision. The theoretical performance is analyzed with corresponding proof. Finally, comparative simulations are conducted and the results show that the proposed scheme achieves high-precision motion tracking performance and simultaneous high-level synchronization of dual cylinders under unbalanced loads.

Adaptive Robust Cascade Force Control of 1-DOF Joint Exoskeleton for Human Performance Augmentation

2015 ◽  
Author(s):  
Shan Chen ◽  
Bin Yao ◽  
Zheng Chen ◽  
Xiaocong Zhu ◽  
Shiqiang Zhu
Keyword(s):  
Force Control ◽  
Motion Tracking ◽  
Human Performance ◽  
Control Method ◽  
Interaction Force ◽  
Human Motion ◽  
Adaptive Robust Control ◽  
Human Machine Interaction ◽  
High Level ◽  
Machine Interaction

The control objective of exoskeleton for human performance augmentation is to minimize the human machine interaction force while carrying external loads and following human motion. This paper addresses the dynamics and the interaction force control of a 1-DOF hydraulically actuated joint exoskeleton. A spring with unknown stiffness is used to model the human-machine interface. A cascade force control method is adopted with high-level controller generating the reference position command while low level controller doing motion tracking. Adaptive robust control (ARC) algorithm is developed for both two controllers to deal with the effect of parametric uncertainties and uncertain nonlinearities of the system. The proposed adaptive robust cascade force controller can achieve small human-machine interaction force and good robust performance to model uncertainty which have been validated by experiment.

scholarly journals Infants in Control: Prospective Motor Control and Executive Functions in Action Development

2018 ◽  
Author(s):  
Janna M. Gottwald
Keyword(s):  
Motor Control ◽  
Cognitive Control ◽  
Executive Functions ◽  
Visual Information ◽  
Motion Tracking ◽  
Planning Process ◽  
Action Planning ◽  
Sources Of Information ◽  
Action Sequences ◽  
High Level

This thesis assesses the link between action and cognition early in development. Thus the notion of an embodied cognition is investigated by tying together two levels of action control in the context of reaching in infancy: prospective motor control and executive functions. The ability to plan our actions is the inevitable foundation of reaching our goals. Thus actions can be stratified on different levels of control. There is the relatively low level of prospective motor control and the comparatively high level of cognitive control. Prospective motor control is concerned with goal-directed actions on the level of single movements and movement combinations of our body and ensures purposeful, coordinated movements, such as reaching for a cup of coffee. Cognitive control, in the context of this thesis more precisely referred to as executive functions, deals with goal-directed actions on the level of whole actions and action combinations and facilitates directedness towards mid- and long-term goals, such as finishing a doctoral thesis. Whereas prospective motor control and executive functions are well studied in adulthood, the early development of both is not sufficiently understood.This thesis comprises three empirical motion-tracking studies that shed light on prospective motor control and executive functions in infancy. Study I investigated the prospective motor control of current actions by having 14-month-olds lift objects of varying weights. In doing so, multi-cue integration was addressed by comparing the use of visual and non-visual information to non-visual information only. Study II examined the prospective motor control of future actions in action sequences by investigating reach-to-place actions in 14-month-olds. Thus the extent to which Fitts’ law can explain movement duration in infancy was addressed. Study III lifted prospective motor control to a higher that is cognitive level, by investigating it relative to executive functions in 18-months-olds.Main results were that 14-month-olds are able to prospectively control their manual actions based on object weight. In this action planning process, infants use different sources of information. Beyond this ability to prospectively control their current action, 14-month-olds also take future actions into account and plan their actions based on the difficulty of the subsequentaction in action sequences. In 18-month-olds, prospective motor control in manual actions, such as reaching, is related to early executive functions, as demonstrated for behavioral prohibition and working memory. These findings are consistent with the idea that executive functions derive from prospective motor control. I suggest that executive functions could be grounded in the development of motor control. In other words, early executive functions should be seen as embodied.

scholarly journals Terrain-Perception-Free Quadrupedal Spinning Locomotion on Versatile Terrains: Modeling, Analysis, and Experimental Validation

2021 ◽  
Vol 8 ◽  
Author(s):  
Hongwu Zhu ◽  
Dong Wang ◽  
Nathan Boyd ◽  
Ziyi Zhou ◽  
Lecheng Ruan ◽  
...  
Keyword(s):  
Motion Tracking ◽  
Center Of Mass ◽  
Kinematic Model ◽  
Linear Quadratic Regulator ◽  
Small Scale ◽  
Small Range ◽  
Linear Quadratic ◽  
Stability Margins ◽  
Uneven Terrain ◽  
Quadruped Robots

Dynamic quadrupedal locomotion over rough terrains reveals remarkable progress over the last few decades. Small-scale quadruped robots are adequately flexible and adaptable to traverse uneven terrains along the sagittal direction, such as slopes and stairs. To accomplish autonomous locomotion navigation in complex environments, spinning is a fundamental yet indispensable functionality for legged robots. However, spinning behaviors of quadruped robots on uneven terrain often exhibit position drifts. Motivated by this problem, this study presents an algorithmic method to enable accurate spinning motions over uneven terrain and constrain the spinning radius of the center of mass (CoM) to be bounded within a small range to minimize the drift risks. A modified spherical foot kinematics representation is proposed to improve the foot kinematic model and rolling dynamics of the quadruped during locomotion. A CoM planner is proposed to generate a stable spinning motion based on projected stability margins. Accurate motion tracking is accomplished with linear quadratic regulator (LQR) to bind the position drift during the spinning movement. Experiments are conducted on a small-scale quadruped robot and the effectiveness of the proposed method is verified on versatile terrains including flat ground, stairs, and slopes.

Quantum key distribution protocol using random bases

2016 ◽  
Vol 30 (10) ◽  
pp. 1650061
Author(s):  
A. Meslouhi ◽  
H. Amellal ◽  
Y. Hassouni ◽  
M. El Baz ◽  
A. El Allati
Keyword(s):  
Angular Velocity ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Rotational Angle ◽  
High Level ◽  
Quantum Key Distribution Protocol

In order to enhance the quantum key distribution (QKD) security, a new protocol, “QKDPRB” based on random bases is proposed. It consists of using standard encoding bases moving circularly with a variable rotational angle [Formula: see text] which depends on angular velocity [Formula: see text]; thus, the traditional bases turn into relative ones. To prove the security and the efficiency of the protocol, we present a universal demonstration which proves a high level security of the proposed protocol, even in the presence of the intercept and resend attack. Finally, the QKDPRB may improve the security of QKD.

scholarly journals Application of the pseudoinverse computation in reconstruction of blurred images

Filomat ◽  
2012 ◽  
Vol 26 (3) ◽  
pp. 453-465 ◽  
Author(s):  
Sladjana Miljkovic ◽  
Marko Miladinovic ◽  
Predrag Stanimirovic ◽  
Igor Stojanovic
Keyword(s):  
Mathematical Model ◽  
Direct Method ◽  
Motion Blur ◽  
Linear Motion ◽  
Numerical Examples ◽  
High Level ◽  
Blurred Images ◽  
Programming Package ◽  
A Direct Method ◽  
Very High

We present a direct method for removing uniform linear motion blur from images. The method is based on a straightforward construction of the Moore-Penrose inverse of the blurring matrix for a given mathematical model. The computational load of the method is decreased significantly with respect to other competitive methods, while the resolution of the restored images remains at a very high level. The method is implemented in the programming package MATLand respective numerical examples are presented.

scholarly journals Synchronization Control of Large Crawler Crane Driven by Double Winches Using Hook Angle Feedback Information

2015 ◽  
Vol 9 (1) ◽  
pp. 977-981
Author(s):  
Jun Yao ◽  
Yu Tang ◽  
Zhencai Zhu
Keyword(s):  
Control Strategy ◽  
Pid Control ◽  
Synchronization Control ◽  
Small Range ◽  
Variable Speed ◽  
Angle Sensor ◽  
Feedback Information ◽  
Control Scheme ◽  
Crawler Crane ◽  
Synchronization Performance

During the operation of a crawler crane driven by double winches, it is important to make the two winches actuate synchronously so that the hook is in a horizontal state to prevent accidents. In this paper, a novel synchronization control strategy for crawler crane driven by double winches using hook angle feedback information is proposed. The hook angle proportional to the length error of ropes is measured by a wireless angle sensor firstly and is then employed as a feedback control signal. To further improve the synchronization performance, cross-coupled control scheme together with the variable speed PID control is utilized on the basis of the collected hook angle signal. Simulations and experiments are then conducted and the results demonstrate that the proposed control scheme can obtain a better synchronization performance than the conventional control strategy using encoders and the inclination of the hook is greatly reduced to a limited small range.

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