Stability Margin of a Metamorphic Quadruped Robot With a Twisting Trunk

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Chunsong Zhang ◽  
Chi Zhang ◽  
Jian S. Dai ◽  
Peng Qi
Keyword(s):  
Closed Loop ◽  
Stability Margin ◽  
Rigid Bodies ◽  
Quadruped Robot ◽  
Quadruped Robots ◽  
Kinematic Performance ◽  
The Stability ◽  
Twisting Angle

Abstract To date, most quadruped robots are either equipped with trunks that are rigid bodies or consist of blocks connected by passive joints. The kinematic performance of these quadruped robots is only determined by their legs. To release the mobility of trunks and enhance the performance of quadruped robots, this paper proposes a metamorphic quadruped robot with a moveable trunk (a planar six-bar closed-loop linkage), called MetaRobot I, which can implement active trunk motions. The robot can twist its trunk like natural quadrupeds. Through trunk twisting, the stability margin of the quadruped robot can be increased compared with that of a quadruped robot with a rigid trunk. The inner relationship between the stability margin and the twisting angle is analyzed in this paper. Finally, simulations are carried out to show the benefits facilitated by the twisting trunk to the quadruped robot.

Gait Planning and Simulation Analysis of a New Amphibious Quadruped Robots

2018 ◽  
Vol 30 (2) ◽  
pp. 257-264
Author(s):  
Shuo Han ◽  
◽  
Yuan Chen ◽  
Guangying Ma ◽  
Jinshan Zhang ◽  
...  
Keyword(s):  
Simulation Analysis ◽  
Stability Margin ◽  
Quadruped Robot ◽  
Working Environment ◽  
Practical Application ◽  
Quadruped Robots ◽  
Driving Mechanisms ◽  
Adams Software ◽  
New Type ◽  
The Stability

In order to allow quadruped robots to adapt to the complex working environment in the field of fisheries and aquaculture, a new type of quadruped robot with linear and rotary driving is proposed, and the kinematic inverse solution of the leg of the quadruped robot is deduced. For achieving quadruped robot smooth walking, the straight gait of the quadruped robot is planned according to the stability margin principle of motion, so that the stability margin of the machine is 20 mm when three legs supporting it. The planning gait is simulated by ADAMS software, the kinematics and dynamics analysis of the four main driving mechanisms of the robot leg were carried out, and the feasibility of using the STEP5 driving function to execute the planning gait in the quadruped robot was verified. The theoretical and simulation curve analysis results show that, the quadruped robot according to the planned gait can complete the cycle and have a stable walking. The results of this study can provide a reference for the practical application of the new amphibious quadruped robot in the fields of complex and uneven ground in the field of fisheries and aquaculture to realize exploration, fishing and transportation.

scholarly journals Stability-Guaranteed and High Terrain Adaptability Static Gait for Quadruped Robots

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4911
Author(s):  
Qian Hao ◽  
Zhaoba Wang ◽  
Junzheng Wang ◽  
Guangrong Chen
Keyword(s):  
Impedance Control ◽  
Stability Margin ◽  
Planning Method ◽  
Legged Robots ◽  
Gait Planning ◽  
Quadruped Locomotion ◽  
Quadruped Robots ◽  
Adjustment Strategy ◽  
Compliant Behavior ◽  
The Stability

Stability is a prerequisite for legged robots to execute tasks and traverse rough terrains. To guarantee the stability of quadruped locomotion and improve the terrain adaptability of quadruped robots, a stability-guaranteed and high terrain adaptability static gait for quadruped robots is addressed. Firstly, three chosen stability-guaranteed static gaits: intermittent gait 1&2 and coordinated gait are investigated. In addition, then the static gait: intermittent gait 1, which is with the biggest stability margin, is chosen to do a further research about quadruped robots walking on rough terrains. Secondly, a position/force based impedance control is employed to achieve a compliant behavior of quadruped robots on rough terrains. Thirdly, an exploratory gait planning method on uneven terrains with touch sensing and an attitude-position adjustment strategy with terrain estimation are proposed to improve the terrain adaptability of quadruped robots. Finally, the proposed methods are validated by simulations.

Normalized Energy Stability Margin Based Analysis of Omni-Directional Static Walking of a Quadruped Robot on Rough Terrain

2011 ◽  
Vol 383-390 ◽  
pp. 7401-7405
Author(s):  
Lei Zhang ◽  
Shan Gao
Keyword(s):  
Stability Criterion ◽  
Simulation Experiment ◽  
Stability Margin ◽  
Quadruped Robot ◽  
Center Of Gravity ◽  
Energy Stability ◽  
Rough Terrain ◽  
The Stability

With Normalized Energy Stability Margin(Sne ) as stability criterion, this paper studies the tumbles of omni-directional static walking of a quadruped robot around the line connecting two adjacent supporting legs on rough terrain, proposes the method to improve the stability of quadruped robot by increasing the (Sne ) value, which is realized by lowering the height of center of gravity(COG), and finally substantiates the feasibility of the method through a simulation experiment.

scholarly journals Self-Stabilising Quadrupedal Running by Mechanical Design

2009 ◽  
Vol 6 (1) ◽  
pp. 73-85 ◽  
Author(s):  
Panagiotis Chatzakos ◽  
Evangelos Papadopoulos
Keyword(s):  
Mechanical System ◽  
Mechanical Design ◽  
Quadruped Robot ◽  
The Self ◽  
Rough Terrain ◽  
Stable Regime ◽  
Quadruped Robots ◽  
The Stability ◽  
Running Robots ◽  
Body Inertia

Dynamic stability allows running animals to maintain preferred speed during locomotion over rough terrain. It appears that rapid disturbance rejection is an emergent property of the mechanical system. In running robots, simple motor control seems to be effective in the negotiation of rough terrain when used in concert with a mechanical system that stabilises passively. Spring-like legs are a means for providing self-stabilising characteristics against external perturbations. In this paper, we show that a quadruped robot could be able to perform self-stable running behaviour in significantly broader ranges of forward speed and pitch rate with a suitable mechanical design, which is not limited to choosing legs spring stiffness only. The results presented here are derived by studying the stability of the passive dynamics of a quadruped robot running in the sagittal plane in a dimensionless context and might explain the success of simple, open loop running controllers on existing experimental quadruped robots. These can be summarised in (a) the self-stabilised behaviour of a quadruped robot for a particular gait is greatly related to the magnitude of its dimensionless body inertia, (b) the values of hip separation, normalised to rest leg length, and leg relative stiffness of a quadruped robot affect the stability of its motion and should be in inverse proportion to its dimensionless body inertia, and (c) the self-stable regime of quadruped running robots is enlarged at relatively high forward speeds. We anticipate the proposed guidelines to assist in the design of new, and modifications of existing, quadruped robots. As an example, specific design changes for the Scout II quadruped robot that might improve its performance are proposed.

scholarly journals PID control of FOPDT plants with dominant dead time based on the modulus optimum criterion

2016 ◽  
Vol 26 (1) ◽  
pp. 5-17 ◽  
Author(s):  
Jan Cvejn
Keyword(s):  
Linear Systems ◽  
Pid Control ◽  
Pid Controller ◽  
Closed Loop ◽  
Dead Time ◽  
Stability Margin ◽  
Analytical Design ◽  
First Order ◽  
The Stability

The modulus optimum (MO) criterion can be used for analytical design of the PID controller for linear systems with dominant dead time. However, although the method usually gives fast and non-oscillating closed-loop responses, in the case of large dead time the stability margin gets reduced and even non-stable behavior can be observed. In this case a correction of the settings is needed to preserve the stability margin. We describe and compare two methods of design of the PID controller based on the MO criterion that for the stable first-order systems with dead time preserve the stability margin, trying to keep maximum of the performance of the original MO settings.

scholarly journals Stability Criterion for Dynamic Gaits of Quadruped Robot

2018 ◽  
Vol 8 (12) ◽  
pp. 2381 ◽  
Author(s):  
Yan Jia ◽  
Xiao Luo ◽  
Baoling Han ◽  
Guanhao Liang ◽  
Jiaheng Zhao ◽  
...  
Keyword(s):  
Dynamic Stability ◽  
Stability Criterion ◽  
Quadruped Robot ◽  
Stability Criteria ◽  
Irregular Terrain ◽  
Quadruped Robots ◽  
Simulation Results ◽  
Zero Moment ◽  
The Stability ◽  
Dynamic Gait

Dynamic-stability criteria are crucial for robot’s motion planning and balance recovery. Nevertheless, few studies focus on the motion stability of quadruped robots with dynamic gait, none of which have accurately evaluated the robots’ stability. To fill the gaps in this field, this paper presents a new stability criterion for the motion of quadruped robots with dynamic gaits running over irregular terrain. The traditional zero-moment point (ZMP) is improved to analyze the motion on irregular terrain precisely for dynamic gaits. A dynamic-stability criterion and measurement are proposed to determine the stability state of the robot and to evaluate its stability. The simulation results show the limitations of the existing stability criteria for dynamic gaits and indicate that the criterion proposed in this paper can accurately and efficiently evaluate the stability of a quadruped robot using such gaits.

scholarly journals Creeping Gait Analysis and Simulation of a Quadruped Robot

2019 ◽  
Vol 14 (2) ◽  
pp. 93-106
Author(s):  
Firas A. Raheem ◽  
Murtadha Khudhair Flayyih
Keyword(s):  
Sequence Analysis ◽  
Gait Analysis ◽  
Inverse Kinematic ◽  
Quadruped Robot ◽  
Legged Robot ◽  
Stability Margins ◽  
Robot Locomotion ◽  
Quadruped Robots ◽  
Kinematic Models ◽  
The Stability

A quadruped (four-legged) robot locomotion has the potential ability for using in different applications such as walking over soft and rough terrains and to grantee the mobility and flexibility. In general, quadruped robots have three main periodic gaits:  creeping gait, running gait and galloping gait. The main problem of the quadruped robot during walking is the needing to be statically stable for slow gaits such as creeping gait. The statically stable walking as a condition depends on the stability margins that calculated particularly for this gait. In this paper, the creeping gait sequence analysis of each leg step during the swing and fixed phases has been carried out. The calculation of the minimum stability margins depends upon the forward and inverse kinematic models for each 3-DOF leg and depends on vertical geometrical projection during walking. Simulation and results verify the stability insurance after calculation the minimum margins which indicate clearly the robot COG (Center of Gravity) inside the supporting polygon resulted from the leg-tips.

scholarly journals Automated Quadruped Robot Simulation using Internet of Things and MATLAB

2021 ◽  
Vol 2115 (1) ◽  
pp. 012022
Author(s):  
Richik Ray ◽  
Rishita Shanker ◽  
Harsh Gupta ◽  
Mohit Sharan ◽  
Swagatika Mohanty
Keyword(s):  
Internet Of Things ◽  
Damage Control ◽  
Quadruped Robot ◽  
Quadruped Robots ◽  
Simulink Model ◽  
Current Consumption ◽  
Cloud Server ◽  
Key Factor ◽  
Computer Based ◽  
The Stability

Abstract In this paper, a MATLAB Simulink model of a Quadruped Robot is presented alongside its remote, control and monitor user interface that has been developed by using the fundamentals of Internet of Things on a Node-Red Flow and the FRED-Cloud Server. Robotics and Automation over the recent years have developed exponentially and hence have been a key factor in the rise of Industry 4.0 which has usurped manual supervision and operation in industrial and manufacturing processes around the globe. The design and creation of technologically advanced robots integrated with computer-based software for their automation has not only successfully made the tasks facile to manage within short spans of time, but also has increased the efficiency notably. The stability and mobility of quadruped robots is considered to be ideal on differing terrains with minimal subtle changes, thereby making it an asset. Internet of Things on the other hand, has paved its way over the control of robots as well, with its unparalleled benefits. This paper is focused on the design and execution of the Quadiuped model which includes the observation of the various significant graphs achieved post simulation with respect to electrical values such as power and current consumption, and a visual animation of the robot running in the workspace. Furthermore, a single platform is developed and displayed that allows a user to log in for security puiposes and thereby, operate and monitor the functions and conditions of the bot easily, ranging from remote visual support, directional integrity, damage control and more, without the need of multiple platforms to carry out varying tasks with respect to control.

Robust Stability with System Uncertainties

2002 ◽  
Vol 216 (5) ◽  
pp. 495-508 ◽  
Author(s):  
A Whalley ◽  
M Ebrahimi
Keyword(s):  
Closed Loop ◽  
Controller Design ◽  
Stability Margin ◽  
Impedance Matrix ◽  
Multivariable System ◽  
Closed Loop System ◽  
Frequency Domain Methods ◽  
System Uncertainties ◽  
The Stability ◽  
Proportional Controller

Multivariable system models in the form of parameterized, impedance, matrix quadratic realizations are considered. System uncertainties in the form of mass-inertia or damping variations are acknowledged. Simple proportional controller models are proposed and the effect of model variations on the stability of the closed-loop system is investigated. Frequency domain methods are employed to predict the relative stability condition of the system. Conventional stability margin measures may be invoked while adjusting the controller design parameter to an appropriate setting.

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.

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