scholarly journals Gait Planning and Stability Control of a Quadruped Robot

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Junmin Li ◽  
Jinge Wang ◽  
Simon X. Yang ◽  
Kedong Zhou ◽  
Huijuan Tang
Keyword(s):  
Stability Control ◽  
Quadruped Robot ◽  
Oscillation System ◽  
Hip Joints ◽  
Gait Planning ◽  
Reduced Order ◽  
System A ◽  
The Stability ◽  
Real Time Computing ◽  
Speed Adjustment

In order to realize smooth gait planning and stability control of a quadruped robot, a new controller algorithm based on CPG-ZMP (central pattern generator-zero moment point) is put forward in this paper. To generate smooth gait and shorten the adjusting time of the model oscillation system, a new CPG model controller and its gait switching strategy based on Wilson-Cowan model are presented in the paper. The control signals of knee-hip joints are obtained by the improved multi-DOF reduced order control theory. To realize stability control, the adaptive speed adjustment and gait switch are completed by the real-time computing of ZMP. Experiment results show that the quadruped robot’s gaits are efficiently generated and the gait switch is smooth in the CPG control algorithm. Meanwhile, the stability of robot’s movement is improved greatly with the CPG-ZMP algorithm. The algorithm in this paper has good practicability, which lays a foundation for the production of the robot prototype.

On the Dynamical Systems Stability Control and Applications

2014 ◽  
Vol 555 ◽  
pp. 361-368
Author(s):  
Marcel Migdalovici ◽  
Daniela Baran ◽  
Gabriela Vlădeanu
Keyword(s):  
Dynamical System ◽  
Dynamical Systems ◽  
Nonlinear System ◽  
Stability Control ◽  
Necessary Condition ◽  
Linear Dynamical Systems ◽  
System A ◽  
First Approximation ◽  
Free Parameters ◽  
The Stability

The stability control analyzed by us, in this show, is based on our results in the domain of dynamical systems that depend of parameters. Any dynamical system can be considered as dynamical system that depends of parameters, without numerical particularization of them. All concrete dynamical systems, meted in the specialized literature, underline the property of separation between the stable and unstable zones, in sense of Liapunov, for two free parameters. This property can be also seen for one or more free parameters. Some mathematical conditions of separation between stable and unstable zones for linear dynamical systems are identified by us. For nonlinear systems, the conditions of separation may be identified using the linear system of first approximation attached to nonlinear system. A necessary condition of separation between stable and unstable zones, identified by us, is the sufficient order of differentiability or conditions of continuity for the functions that define the dynamical system. The property of stability zones separation can be used in defining the strategy of stability assurance and optimizing of the parameters, in the manner developed in the paper. The cases of dynamical systems that assure the separations of the stable and unstable zones, in your evolution, and permit the stability control, are analyzed in the paper.

scholarly journals Dynamic Imbalance Analysis and Stability Control of Galloping Gait for a Passive Quadruped Robot

2015 ◽  
Vol 2015 ◽  
pp. 1-17 ◽  
Author(s):  
Chunlei Wang ◽  
Ting Zhang ◽  
Xiaohui Wei ◽  
Yongjun Long ◽  
Shigang Wang
Keyword(s):  
Stability Criterion ◽  
Center Of Mass ◽  
Zero Point ◽  
Stability Control ◽  
Quadruped Robot ◽  
Peak Time ◽  
Flight Phase ◽  
Trunk Posture ◽  
The Stability ◽  
Necessary And Sufficient

Some imbalance and balance postures of a passive quadruped robot with a simplified mathematical model are studied. Through analyzing the influence of the touchdown angle of the rear leg on the posture of the trunk during the flight phase, the stability criterion is concluded: the closer are the two moments which are the zero time of the pitching angle and the peak time of the center of mass, the better is the stability of the trunk posture during the flight phase. Additionally, the validity of the stability criterion is verified for the cat, greyhound, lion, racehorse, basset hound, and giraffe. Furthermore, the stability criterion is also applicable when the center of the mass of body is shifted. Based on the stability criterion, the necessary and sufficient condition of the galloping stability for the quadruped robot is proposed to attain a controlled thrust. The control strategy is designed by an optimization dichotomy algorithm for seeking the zero point of the balance condition. Through the control results, it is demonstrated that the imbalance posture of the trunk could be stabilized by adjusting the stiffness of four legs.

scholarly journals Adaptive Walking Control for a Quadruped Robot on Irregular Terrain Using the Complex-Valued CPG Network

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2090
Author(s):  
Yong Zhang ◽  
Hao Wang ◽  
Yi Ding ◽  
Beiping Hou
Keyword(s):  
Control System ◽  
Quadruped Robot ◽  
Network Control ◽  
Joint Angles ◽  
Gait Planning ◽  
Irregular Terrain ◽  
Dc Motors ◽  
System A ◽  
Unit Model ◽  
Complex Valued

In this paper, we propose a CPG (central pattern generator) network control system using motor dynamics for the gait planning of a quadruped robot with a trot walking pattern to climb up and down a slope and turn back and follow the symmetry of route. The CPG unit model, which includes two DC motors model, has the ability to generate the periodic joint angle with complex-value parameters. Through plural feedback parameters, the CPG network can adjust the frequency and amplitude of an internal neuron model such as a robot meeting an irregular surface of a road. Using the stride length and frequency of robot joint angles, the distance of walking with a trot pattern can be calculated. In order to confirm the validity of the proposed control system, a quadruped robot is produced to implement the adaptive walking system.

scholarly journals About mixed forced, parametric and self-oscillations by limited excitation and delayed elasticity

2020 ◽  
pp. 12-19
Author(s):  
A. A Alifov
Keyword(s):  
Energy Source ◽  
Metal Cutting ◽  
Amplitude Curve ◽  
Labor Costs ◽  
Oscillation System ◽  
System A ◽  
Oscillation Modes ◽  
Final Design ◽  
Limited Power ◽  
The Stability

Mixed forced, parametric, and self-oscillations are considered if there is a delay in the elastic force in the system. A dynamic model is a friction self-oscillation system describing the frictional self-oscillations that occur in many technical systems for various purposes (metal-cutting machines, textile equipment, brakes and a number of other engineering objects). The operation of the system is supported by the energy source of limited power. For the analysis we used the method of straight linearization which is easier than the known methods of analysis of nonlinear systems, has no time-consuming and complex approximations of different orders, provides an opportunity to obtain the final design ratios regardless of the specific type and degree of nonlinearity, thus reducing labor costs and time by several orders of magnitude. By using this method, we obtained solutions of a nonlinear system of differential equations describing the system's motion. The equations of non-stationary and stationary movements are derived. To analyze the stability of stationary movements, the stability conditions based on the Routh-Hurwitz criteria are compiled. Calculations were performed to obtain information about the effect of delay on the oscillation modes. It is shown that the delay affects both the magnitude of the amplitude and the location of the amplitude-frequency curve in the frequency range depending on the magnitude of the delay, the amplitude curve is shifted to the region of lower frequencies. The stability of stationary oscillations depends both on the energy source characteristics and lag value. The interaction of the oscillating system and the energy source leads to a number of effects, both in the presence and absence of the lag. However, their course may be different depending on the lag value.

Gait Planning of Quadruped Robot Walking on a Slope Based on Static Balance

2013 ◽  
Vol 373-375 ◽  
pp. 282-286 ◽  
Author(s):  
Wen Yu Zhang ◽  
Lei Zhang
Keyword(s):  
Center Of Pressure ◽  
Quadruped Robot ◽  
Joint Torque ◽  
Static Balance ◽  
Gait Transition ◽  
Gait Planning ◽  
Motion Speed ◽  
Walking Environment ◽  
Movement Parameters ◽  
The Stability

Gait planning affects stability, motion speed, and joint torque of quadruped robot etc. Also, it is necessary to consider movement parameters of slope walking environment such as the inclination angle, the movement area of feet and so on. The stability criterion on the basis of center of pressure is chosen to analyze the stability during the movement. Based on static balance, the omni-directional walking of quadruped robot on a slope is planned. CFP is set in order to reduce the transition steps. Then the start and end positions of swinging leg and supporting leg is calculated. The process of gait transition is planned to make sure stable and continuous movement. The experiment verifies the validity of the proposed method.

Stability Region-Based Analysis of Walking and Push Recovery Control

2020 ◽  
Author(s):  
William Z. Peng ◽  
Hyunjong Song ◽  
Joo H. Kim
Keyword(s):  
Biped Robot ◽  
Step Length ◽  
Stability Control ◽  
Human Gait ◽  
Biped Robots ◽  
Reduced Order ◽  
Double Support ◽  
Push Recovery ◽  
The Stability ◽  
Time Required

Abstract Push recovery is a vital aspect of balance stability control in biped robots. In this work, the response of a biped system to unexpected external perturbations is analyzed for different tasks and controllers using stability criteria based on balanced and steppable regions. The steppable region for a given step length and the balanced regions for single and double support contacts are constructed for a biped robot using optimization with its system dynamics, kinematic limits, actuation limits, and contact interactions with the environment. The regions are compared with those of a human subject to demonstrate that human gait exhibits unbalanced (but steppable) phases largely absent in robotic gait. These regions are also applied to a comparative analysis against capturability, where the computed steppable region is significantly larger than the capture region of an equivalent reduced-order model. The stability regions are also used to compare the performance of controllers during a double support balancing task. The implemented hip, knee, and ankle strategy-based controller led to improved stabilization — i.e., decreased foot tipping and time required to balance — relative to an existing hip and ankle controller and a gyro feedback controller. The proposed approaches are applicable to the analysis of any bipedal task and stability controller in general.

The simplest creeping gait for a quadruped robot

2012 ◽  
Vol 227 (1) ◽  
pp. 170-177 ◽  
Author(s):  
Fei Liu ◽  
Dan Wu ◽  
Ken Chen
Keyword(s):  
Mathematical Description ◽  
Degrees Of Freedom ◽  
Stability Margin ◽  
Geometrical Model ◽  
Quadruped Robot ◽  
Center Of Gravity ◽  
Gait Planning ◽  
Directional Stability ◽  
The Stability ◽  
Initial Pattern

This article presents the simplest creeping gait (creeping gait with one center-of-gravity movement in a cycle) for a quadruped robot. The creeping gait with one center-of-gravity movement is efficient in reducing the complexity of gait planning and the control of quadrupeds. To find the simplest creeping gait, the geometrical model of a quadruped is constructed, and the omni-directional stability margin is derived to determine the stability. Based on the features of creeping gaits, the simplest possible gait is analyzed. The mathematical description is used to describe the simplest gait with the maximum omni-directional stability margin. Details of the creeping gait, including its initial pattern and its sequences, are provided. In a cycle of the creeping gait with one center-of-gravity movement, the center of gravity needs to move only once. Only 16 commands are required to move a quadruped with two degrees of freedom in each leg. An experiment conducted on the THU-WL robot proves that the gait is reliable and stable. The creeping gait with one center-of-gravity movement is a remarkable simplification for the creeping gait.

NPLs — The Solution Recipe for Albania

2015 ◽  
Vol 3 (1) ◽  
pp. 48
Author(s):  
Elona Shehu ◽  
Elona Meka
Keyword(s):  
Interest Rate ◽  
Negative Relationship ◽  
Banking System ◽  
Gdp Growth ◽  
System A ◽  
Analysis Technique ◽  
Recent Financial Crisis ◽  
The Stability ◽  
Asset Quality ◽  
Macroeconomic Determinants

The quality of the loan portfolio in Albanian banking system is facing many obstacles during the last decade. In this paper we look at possible determinants of assets quality. During the recent financial crisis commercial banks were confronted with deteriorating asset quality that threatened not only the banking industry, but also the stability of the entire financial system. This study aims to examine the correlation between non-performing loans and the macroeconomic determinants in Albania during the last decade. NPLs are considered to be of a high importance as they represent the high risk exposure of banking system. A solid bank with healthy assets increases the market efficiency. Our approach is based on a panel data regression analysis technique from 2005-2015. Within this methodology this study finds robust evidence on the existing relationship between lending interest rate, real GDP growth and NPLs. We expect to find a negative relationship between lending interest rate and asset quality. Further we assume an inverse relationship between GDP growth and non-performing loans, suggesting that NPLs decrease if the economy is growing. Furthermore this study proposes a solution platform, which looks deeper into the possibility of creating a secondary active market for troubled loans, restructuring the banking system or implementing the Podgorica model. This research paper opens a new lieu of discussion in terms of academic debates and decision-making policies.

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