scholarly journals Echo State Networks for Estimating Exteroceptive Conditions From Proprioceptive States in Quadruped Robots

2021 ◽  
Vol 15 ◽  
Author(s):  
Mario Calandra ◽  
Luca Patanè ◽  
Tao Sun ◽  
Paolo Arena ◽  
Poramate Manoonpong
Keyword(s):  
Mechanical Design ◽  
Sensory System ◽  
Quadruped Robot ◽  
Proprioceptive Information ◽  
Reservoir Computing ◽  
Quadruped Robots ◽  
Echo State Networks ◽  
Dynamic Estimation ◽  
Reaction Forces ◽  
Computing Structure

We propose a methodology based on reservoir computing for mapping local proprioceptive information acquired at the level of the leg joints of a simulated quadruped robot into exteroceptive and global information, including both the ground reaction forces at the level of the different legs and information about the type of terrain traversed by the robot. Both dynamic estimation and terrain classification can be achieved concurrently with the same reservoir computing structure, which serves as a soft sensor device. Simulation results are presented together with preliminary experiments on a real quadruped robot. They demonstrate the suitability of the proposed approach for various terrains and sensory system fault conditions. The strategy, which belongs to the class of data-driven models, is independent of the robotic mechanical design and can easily be generalized to different robotic structures.

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 A Bio-Inspired Compliance Planning and Implementation Method for Hydraulically Actuated Quadruped Robots with Consideration of Ground Stiffness

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2838
Author(s):  
Xiaoxing Zhang ◽  
Haoyuan Yi ◽  
Junjun Liu ◽  
Qi Li ◽  
Xin Luo
Keyword(s):  
Harmonic Oscillation ◽  
Ground Surface ◽  
Legged Locomotion ◽  
Soft Ground ◽  
Quadruped Robots ◽  
In Series ◽  
Reaction Forces ◽  
Implementation Method ◽  
The Stability ◽  
Natural Dynamics

There has been a rising interest in compliant legged locomotion to improve the adaptability and energy efficiency of robots. However, few approaches can be generalized to soft ground due to the lack of consideration of the ground surface. When a robot locomotes on soft ground, the elastic robot legs and compressible ground surface are connected in series. The combined compliance of the leg and surface determines the natural dynamics of the whole system and affects the stability and efficiency of the robot. This paper proposes a bio-inspired leg compliance planning and implementation method with consideration of the ground surface. The ground stiffness is estimated based on analysis of ground reaction forces in the frequency domain, and the leg compliance is actively regulated during locomotion, adapting them to achieve harmonic oscillation. The leg compliance is planned on the condition of resonant movement which agrees with natural dynamics and facilitates rhythmicity and efficiency. The proposed method has been implemented on a hydraulic quadruped robot. The simulations and experimental results verified the effectiveness of our method.

scholarly journals The Complex Dynamic Locomotive Control and Experimental Research of a Quadruped-Robot Based on the Robot Trunk

2019 ◽  
Vol 9 (18) ◽  
pp. 3911 ◽  
Author(s):  
Dongyi Ren ◽  
Junpeng Shao ◽  
Guitao Sun ◽  
Xuan Shao
Keyword(s):  
Control Strategy ◽  
Kinematic Model ◽  
Quadruped Robot ◽  
Contact Forces ◽  
Small Magnitude ◽  
Feedback Information ◽  
Joint Torques ◽  
Trunk Motion ◽  
Quadruped Robots ◽  
Leg Motion

The research of quadruped robots is fundamentally motivated by their excellent performance in complex terrain. Maintaining the trunk moving smoothly is the basis of assuring the stable locomotion of the robot. In this paper we propose a planning and control strategy for the pacing gait of hydraulic quadruped robots based on the centroid. Initially, the kinematic model between the single leg and the robot trunk was established. The coupling of trunk motion and leg motion was elaborated on in detail. Then, the real-time attitude feedback information of the trunk was considered, the motion trajectory of the trunk centroid was planned, and the foot trajectory of the robot was carried out. Further, the joint torques were calculated that fulfillment minimization of the contact forces. The position and attitude of the robot trunk were adjusted by the presented controller. Finally, the performance of the proposed control framework was tested in simulations and on a robot platform. By comparing the attitude of the robot trunk, the experimental results show that the trunk moved smoothly with small-magnitude by the proposed controller. The stable dynamic motion of the hydraulic quadruped robot was accomplished, which verified the effectiveness and feasibility of the proposed control strategy.

scholarly journals Gait Tracking Control of Quadruped Robot Using Differential Evolution Based Structure Specified Mixed SensitivityH∞Robust Control

2016 ◽  
Vol 2016 ◽  
pp. 1-18 ◽  
Author(s):  
Petrus Sutyasadi ◽  
Manukid Parnichkun
Keyword(s):  
Tracking Control ◽  
Control Algorithm ◽  
Joint Angle ◽  
Gait Pattern ◽  
Quadruped Robot ◽  
Robust Controller ◽  
Quadruped Robots ◽  
Parameter Variations ◽  
Real Hardware ◽  
Dynamic Gait

This paper proposed a control algorithm that guarantees gait tracking performance for quadruped robots. During dynamic gait motion, such as trotting, the quadruped robot is unstable. In addition to uncertainties of parameters and unmodeled dynamics, the quadruped robot always faces some disturbances. The uncertainties and disturbances contribute significant perturbation to the dynamic gait motion control of the quadruped robot. Failing to track the gait pattern properly propagates instability to the whole system and can cause the robot to fall. To overcome the uncertainties and disturbances, structured specified mixed sensitivityH∞robust controller was proposed to control the quadruped robot legs’ joint angle positions. Before application to the real hardware, the proposed controller was tested on the quadruped robot’s leg planar dynamic model using MATLAB. The proposed controller can control the robot’s legs efficiently even under uncertainties from a set of model parameter variations. The robot was also able to maintain its stability even when it was tested under several terrain disturbances.

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.

MECHANICAL DESIGN OF A LEGGED-WHEEL HYBRID QUADRUPED ROBOT FOR MULTI-TERRAIN NAVIGATION

2012 ◽  
pp. 261-265
Author(s):  
HARSHAL UPADHYAY ◽  
GAURAV KUMAR JAISWAL
Keyword(s):  
Mechanical Design ◽  
Quadruped Robot ◽  
Good Stability ◽  
High Speeds ◽  
Hybrid Platform

The two most common modes of locomotion used by humans are legged mode and wheeled mode, the former an inherent gift while the latter being an ingenious invention on their part. While both have their advantages, they may fall short in some aspects for instance, legs may fail in terms of high speeds and wheels might prove not so handy in the more demanding and uneven terrains Thus, a leg-wheel hybrid platform promises to ensure both high speeds and good stability on a variety of terrains .

Full Leg Control of a Quadruped Robot Using Linear Visual Servoing with a Stereo Omnidirectional Camera

2011 ◽  
Vol 5 (2) ◽  
pp. 241-246
Author(s):  
Yukinari Inoue ◽  
◽  
Noriaki Maru ◽  
Keyword(s):  
Visual Servoing ◽  
Visual Space ◽  
Quadruped Robot ◽  
The Body ◽  
Field Of View ◽  
Transformation Equation ◽  
Stereo Camera ◽  
Omnidirectional Camera ◽  
Quadruped Robots ◽  
Omnidirectional Image

The authors have previously proposed foot tip control for quadruped robots using linear visual servoing (LVS) with a normal stereo camera. However, a normal stereo camera has a narrow field of view and is incapable of seeing all four legs simultaneously. Consequently, it has been a problem that the control of all the legs have required that the rotatation of the camera be controlled. This article proposes a method by which a stereo omnidirectional camera is provided at a position low on the body to control all four legs through LVS. In this article, we at first present a transformation equation from an omnidirectional image to a binocular visual space, and we develop a servo equation of LVS in which an omnidirectional image is used. Then, through simulation, we confirm trajectories with the LVS applied to foot tip control. We also conduct an experiment using TITAN-VIII to demonstrate the efficacy of the proposed method.

A Dynamic Analysis Based on MBD ADAMS Program for a Variant of Quadruped Robot

2016 ◽  
Vol 823 ◽  
pp. 429-434 ◽  
Author(s):  
Florina Pop ◽  
Erwin Christian Lovasz ◽  
Valer Dolga ◽  
Marco Ceccarelli ◽  
Dan Mărgineanu ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
3D Model ◽  
Quadruped Robot ◽  
Moment Of Inertia ◽  
Ground Reaction Forces ◽  
Generalized Coordinates ◽  
Mass Moment ◽  
Adams Software ◽  
Mass Moment Of Inertia ◽  
Reaction Forces

For stability and impact reaction forces assessment of a quadruped robot during walking, a dynamic analysis is considered. For this purpose, a variant of a quadruped robot based on Jansen mechanism is presented. For interpreting the influence of the reaction forces from the ground during walking, the analysis was conducted with help of ADAMS software using a 3D model of the robot. Material specifications, forces and moments acting in the robot structure were considered. Graphical results obtained regarding the ground reaction forces are displayed. Also a reduced mass moment of inertia at the crankshaft is taken into consideration based on Lagrange motion equation and generalized coordinates.

scholarly journals FPGA-Based Stochastic Echo State Networks for Time-Series Forecasting

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Miquel L. Alomar ◽  
Vincent Canals ◽  
Nicolas Perez-Mora ◽  
Víctor Martínez-Moll ◽  
Josep L. Rosselló
Keyword(s):  
Neural Networks ◽  
Time Series ◽  
Power Dissipation ◽  
Hardware Implementation ◽  
Functional System ◽  
Time Series Forecasting ◽  
Reservoir Computing ◽  
New Approach ◽  
Echo State Networks ◽  
Learning Capabilities

Hardware implementation of artificial neural networks (ANNs) allows exploiting the inherent parallelism of these systems. Nevertheless, they require a large amount of resources in terms of area and power dissipation. Recently, Reservoir Computing (RC) has arisen as a strategic technique to design recurrent neural networks (RNNs) with simple learning capabilities. In this work, we show a new approach to implement RC systems with digital gates. The proposed method is based on the use of probabilistic computing concepts to reduce the hardware required to implement different arithmetic operations. The result is the development of a highly functional system with low hardware resources. The presented methodology is applied to chaotic time-series forecasting.

Topology Configuration of Actuator Failure Mode of a Novel Quadruped Robot

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Jing Wang ◽  
Feng Gao ◽  
Yong Zhang
Keyword(s):  
Fault Tolerance ◽  
Motion Planning ◽  
Failure Mode ◽  
Quadruped Robot ◽  
Actuator Failure ◽  
End Effector ◽  
Actuator Failures ◽  
Quadruped Robots ◽  
Intersection Operation ◽  
Sets Theory

Fault tolerance is an important characteristic of quadruped robots. Actuator failure mode is the basis for research of fault tolerance and motion planning of quadruped robots. In this paper, the combination of actuator failures and the remained end-effector characteristics are investigated based on “GF sets” theory. With intersection operation property in “GF sets,” the remained motion ability can be easily judged. The combination of one and two actuator failures is analyzed in detail and some examples are used to illustrate the method of motion ability analysis. Experiments are carried out on the prototype of a novel quadruped robot and the results show that this method is effective for analysis of fault tolerance of quadruped robots.

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