Walking Robot for Moving on Vertical and Arbitrarily Oriented Surfaces

2021 ◽  
Vol 22 (11) ◽  
pp. 585-593
Author(s):  
V. V. Serebrennyj ◽  
A. A. Boshlyakov ◽  
S. V. Kalinichenko ◽  
A. I. Ogorodnik ◽  
K. V. Konovalov
Keyword(s):  
Degrees Of Freedom ◽  
Impedance Control ◽  
Kinematic Chain ◽  
Important Criterion ◽  
Walking Robot ◽  
Current Vector ◽  
Industrial Structures ◽  
Support Surfaces ◽  
The Moment ◽  
Step Over

The article deals with the design of a walking robot with gripping devices that allow the robot to move on arbitrarily oriented surfaces in space. Such robots are relevant primarily for the inspection of various industrial structures. A model of a two-support robot with gripping devices that allow it to be attached to support surfaces with a small curvature, but arbitrarily oriented in space, is proposed. To ensure attachment to the support surfaces, the robot is designed with five degrees of freedom. An important criterion is the possibility of dexterous movement on surfaces. One of the degrees of freedom of the robot was made linear, which makes it easier to step over obstacles and allows you to implement simpler walking algorithms. When the robot is attached to the supporting surfaces by two gripping devices at once, the kinematic chain is closed. This can lead to an increase in forces and moments in the robot’s links. In this paper, it is applied to use two methods of controlling the drives of the links together – the implementation of impedance control by introducing feedback on the evaluation of the moment based on the motor currents and ensuring the pliability of the gripping devices due to its own elasticity. A mathematical simulation of the robot was carried out, which showed the possibility of reducing the forces in the robot links when attaching the robot to two support surfaces at the same time. The best results were achieved when controlling the current vector of a synchronous motor and using current signals to implement impedance control.

Functional and Constructive Optimization of a Serial-Modular Industrial Robot Implemented within a Single Purpose Flexible Manufacturing Cell

2012 ◽  
Vol 186 ◽  
pp. 239-246
Author(s):  
Silviu Mihai Petrişor ◽  
Ghiţă Bârsan
Keyword(s):  
Flexible Manufacturing ◽  
Degrees Of Freedom ◽  
Industrial Robot ◽  
Kinematic Chain ◽  
Chain Structure ◽  
Calculation Algorithm ◽  
Flexible Manufacturing Cell ◽  
Manufacturing Cell ◽  
Lagrangian Equations ◽  
Selection Of

The authors of this paper aim to highlight the basic design of a flexible manufacturing cell destined for the final processing of water radiators used for AAVs, cell serviced by a serial modular industrial robot possessing in its kinematic chain structure three degrees of freedom, RRT SIL type. The paper outlines the concept, calculation and design of the (MRB) rotation module at the studied industrial robot’s base and of the (MT) translation module of the prehension device attached to the robotic arm. Depending on the organological elements that are part of the MRB rotation module and based on a rigorous dynamic study performed on robotic modules, modeling conducted with the help of Lagrangian equations of the second kind, a dynamic-organological calculation algorithm was obtained for the selection of the appropriate driving servomotor necessary to putting the rotation movable system into service. The last part of the paper deals with the flexible manufacturing cell, together with the calculations related to profitability, economy and investment return duration, following the implementation of the RRT SIL-type industrial robot.

Design of a Sensor System for a Minimalistic Walking Robot with Two Degrees of Freedom

2021 ◽  
Author(s):  
Lyubomira Miteva ◽  
Ivan Chavdarov ◽  
Kaloyan Yovchev ◽  
Bozhidar Naydenov
Keyword(s):  
Degrees Of Freedom ◽  
Sensor System ◽  
Walking Robot ◽  
Two Degrees Of Freedom

ROTATIONS AND VIBRATIONS OF FULLERENES IN THE MOLECULAR COMPLEX C20@C80

2021 ◽  
pp. 35-48
Author(s):  
M.A. Bubenchikov ◽  
◽  
A.M. Bubenchikov ◽  
D.V. Mamontov ◽  
◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Classical Mechanics ◽  
Rotation Frequency ◽  
Dynamic State ◽  
Large Molecules ◽  
Rotational Degrees Of Freedom ◽  
Rotational Motions ◽  
Centers Of Mass ◽  
The Moment

The aim of this work is to apply classical mechanics to a description of the dynamic state of C20@C80 diamond complex. Endohedral rotations of fullerenes are of great interest due to the ability of the materials created on the basis of onion complexes to accumulate energy at rotational degrees of freedom. For such systems, a concept of temperature is not specified. In this paper, a closed description of the rotation of large molecules arranged in diamond shells is obtained in the framework of the classical approach. This description is used for C20@C80 diamond complex. Two different problems of molecular dynamics, distinguished by a fixing method for an outer shell of the considered bimolecular complex, are solved. In all the cases, the fullerene rotation frequency is calculated. Since a class of possible motions for a single carbon body (molecule) consists of rotations and translational displacements, the paper presents the equations determining each of these groups of motions. Dynamic equations for rotational motions of molecules are obtained employing the moment of momentum theorem for relative motions of the system near the fullerenes’ centers of mass. These equations specify the operation of the complex as a molecular pendulum. The equations of motion of the fullerenes’ centers of mass determine vibrations in the system, i.e. the operation of the complex as a molecular oscillator.

Parametric Resonance of a Two Degrees-of-Freedom System Induced by Bounded Noise

2009 ◽  
Vol 76 (4) ◽  
Author(s):  
Jinyu Zhu ◽  
W.-C. Xie ◽  
Ronald M. C. So ◽  
X. Q. Wang
Keyword(s):  
Lyapunov Exponents ◽  
Parametric Resonance ◽  
Degrees Of Freedom ◽  
Singular Perturbation Method ◽  
Bounded Noise ◽  
Two Degrees Of Freedom ◽  
Moment Lyapunov Exponent ◽  
The Moment ◽  
Combined Resonance ◽  
Moment Lyapunov Exponents

The dynamic stability of a two degrees-of-freedom system under bounded noise excitation with a narrowband characteristic is studied through the determination of moment Lyapunov exponents. The partial differential eigenvalue problem governing the moment Lyapunov exponent is established. For weak noise excitations, a singular perturbation method is employed to obtain second-order expansions of the moment Lyapunov exponents and Lyapunov exponents, which are shown to be in good agreement with those obtained using Monte Carlo simulation. The different cases when the system is in subharmonic resonance, combination additive resonance, and combined resonance in the absence of noise, respectively, are considered. The effects of noise and frequency detuning on the parametric resonance are investigated.

scholarly journals Determination of Neuromuscular Control of the Upper Limbs in Children - Case Study

2020 ◽  
Vol 11 (4Sup1) ◽  
pp. 46-61
Author(s):  
Carmen-Magdalena Camenidis ◽  
◽  
Irina Băițel ◽  
Amalia Oatu ◽  
Octavian Amzulescu ◽  
...  
Keyword(s):  
Kinematic Chain ◽  
Neuromuscular Control ◽  
Female Gender ◽  
Upper Limbs ◽  
Motor Action ◽  
Muscle Groups ◽  
The Moment ◽  
The Right

The objective of this case study is to observe the existence of an anticipation mechanism at the muscle groups level of the upper limbs. We tried to highlighted this anticipation process by measuring the potential of surface electric for some muscle groups representing the kinematic chain on the right side, involved in the motor action of catching a basketball and a 3kg medicine ball with two hands to the chest. We conducted a case study of a 13-year-old child, female gender. As a measurement method, we used surface electromyography signals of the EMG Trigno Delsys wireless system with 16 electrodes. We determined the moment when the muscles come into action by increasing the potential of surface electric and the moment when the action of catching the ball takes place, using the information provided by the accelerometers incorporated in the sensors of the Delsys equipment used. Therefore, we obtained information about how different muscle groups come into action which helped us to get an idea of how the child's movement is structured. Based on results of accelerations and EMG signals acquired we have formulated conclusions regarding the neuromuscular control of the tested subject. We also planned for the future to test a larger group of participants in the study research of anticipation mechanism in children who do not practice any performance sports.

scholarly journals MOMENT LYAPUNOV EXPONENTS AND STOCHASTIC STABILITY OF A THIN-WALLED BEAM SUBJECTED TO AXIAL LOADS AND END MOMENTS

2021 ◽  
Vol 19 (2) ◽  
pp. 209
Author(s):  
Goran Janevski ◽  
Predrag Kozić ◽  
Ratko Pavlović ◽  
Strain Posavljak
Keyword(s):  
Lyapunov Exponent ◽  
Lyapunov Exponents ◽  
Degrees Of Freedom ◽  
Simulation Method ◽  
Stochastic Dynamic ◽  
Regular Perturbation ◽  
Thin Walled ◽  
The Moment ◽  
Moment Stability ◽  
Moment Lyapunov Exponents

In this paper, the Lyapunov exponent and moment Lyapunov exponents of two degrees-of-freedom linear systems subjected to white noise parametric excitation are investigated. The method of regular perturbation is used to determine the explicit asymptotic expressions for these exponents in the presence of small intensity noises. The Lyapunov exponent and moment Lyapunov exponents are important characteristics for determining both the almost-sure and the moment stability of a stochastic dynamic system. As an example, we study the almost-sure and moment stability of a thin-walled beam subjected to stochastic axial load and stochastically fluctuating end moments.  The validity of the approximate results for moment Lyapunov exponents is checked by numerical Monte Carlo simulation method for this stochastic system.

Design of a Four Legged Parallel Mechanism to Improve the Dexterity of Walking Robot

2009 ◽  
Author(s):  
ChiHyo Kim ◽  
KunWoo Park ◽  
TaeSung Kim ◽  
MinKi Lee
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Topology Design ◽  
Condition Numbers ◽  
Walking Robots ◽  
Rough Terrain ◽  
Parallel Mechanisms ◽  
Walking Robot ◽  
Intermediate Mechanism

This paper designs a four legged parallel mechanism to improve the dexterity of three layered parallel walking robot. Topology design is conducted for a leg mechanism composed of four legs, base and ground, which constitute a redundant parallel mechanism. This mechanism is subdivided into four sub-mechanism composed of three legs. A motor vector is adopted to determine the 6×8 Jacobian of the redundant parallel mechanism and the 6×6 Jacobian of the sub-mechanisms, respectively. The condition number of the Jacobian matrix is used as an index to measure a dexterity. We analyze the condition numbers of the Jacobian over the positional and orientational walking space. The analytical results show that a sub-mechanism has lots of singularities within workspace but they are removed by a redundant parallel mechanism improving the dexterity. This paper presents a parallel typed walking robot to enlarge walking space and stability region. Seven types of three layered walking robots are designed by inserting an intermediate mechanism between the upper and the lower legged parallel mechanisms. They provide various types of gaits to walk rough terrain and climb over a wall with small degrees of freedom.

PSEUDO PROBABILISTIC APPROACH TO TEST ISOMORPHISM AMONG KINEMATIC CHAINS

1997 ◽  
Vol 21 (2) ◽  
pp. 65-83 ◽  
Author(s):  
S. Shubhashis ◽  
M. Choubey ◽  
A.C. Rao
Keyword(s):  
Numerical Scheme ◽  
Degrees Of Freedom ◽  
Probabilistic Approach ◽  
Kinematic Chain ◽  
Single Degree Of Freedom ◽  
Reliable Test ◽  
Kinematic Chains ◽  
Single Degree ◽  
Unique Method ◽  
P Matrix

There is no dearth of methods to test isomorphism amongst kinematic chains. Search for a computationally easier, logically simple and unique method is still on. Present work is in quest of a reliable test to detect isomorphism among kinematic chains. Work presented here is more versatile as it incorporates more features of the kinematic chain which were not included earlier such as number and type of links, their relative dispositions in the kinematic chain, nature of adjacent links etc. The method proposed is based on the concept of pseudo-probability (pseudo means it appears to be, but not exactly. The approach does not follow in-toto the principles of probability and considerable liberty has been taken in interpreting the word probability hence the word pseudo is used along with the probability schemes). Using the resemblance of different coloured balls in an urn for the number and type of links in a kinematic chain, a matrix (named P-Matrix) representing the kinematic chain in totality is generated. For the sake of comparison a numerical scheme named, pseudo probability scheme, P-Scheme, is developed from the above P-Matrix and is used for testing isomorphism. In fact the method is more powerful in the sense that each row of the proposed P-Matrix is capable of representing the respective kinematic chain distinctly and can be used to compare the kinematic chains with same link assortments, uniquely. The proposed method, besides possessing the potential of testing the isomorphism among simple-joint, single degree of freedom kinematic chains is also capable of multi degrees of freedom and multiple-joint kinematic chains.

scholarly journals Kinematic Strategies in Newly Walking Toddlers Stepping Over Different Support Surfaces

2010 ◽  
Vol 103 (3) ◽  
pp. 1673-1684 ◽  
Author(s):  
Nadia Dominici ◽  
Yuri P. Ivanenko ◽  
Germana Cappellini ◽  
Maria Luisa Zampagni ◽  
Francesco Lacquaniti
Keyword(s):  
Degrees Of Freedom ◽  
Walking Speed ◽  
Search Space ◽  
Systematic Change ◽  
Support Surface ◽  
Coordination Pattern ◽  
Surface Conditions ◽  
Surface Inclination ◽  
Support Surfaces ◽  
Inclined Surface

In adults, locomotor movements are accommodated to various support surface conditions by means of specific anticipatory locomotor adjustments and changes in the intersegmental coordination. Here we studied the kinematic strategies of toddlers at the onset of independent walking when negotiating various support surface conditions: stepping over an obstacle, walking on an inclined surface, and on a staircase. Generally, toddlers could perform these tasks only when supported by the arm. They exhibited strategies very different from those of the adults. Although adults maintained walking speed roughly constant, toddlers markedly accelerated when walking downhill or downstairs and decelerated when walking uphill or upstairs. Their coordination pattern of thigh–shank–foot elevation angles exhibited greater inter-trial variability than that in adults, but it did not undergo the systematic change as a function of task that was present in adults. Thus the intersegmental covariance plane rotated across tasks in adults, whereas its orientation remained roughly constant in toddlers. In contrast with the adults, the toddlers often tended to place the foot onto the obstacle or across the edges of the stairs. We interpret such foot placements as part of a haptic exploratory repertoire and we argue that the maintenance of a roughly constant planar covariance—irrespective of the surface inclination and height—may be functional to the exploratory behavior. The latter notion is consistent with the hypothesis proposed decades ago by Bernstein that, when humans start to learn a skill, they may restrict the number of degrees of freedom to reduce the size of the search space and simplify the coordination.

Kinematic and Dynamic Analysis of a Two-Degree-of-Freedom Spherical Wrist

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
M. Ruggiu
Keyword(s):  
Condition Number ◽  
Performance Index ◽  
Degrees Of Freedom ◽  
Kinematic Chain ◽  
Scanning System ◽  
Spherical Wrist ◽  
Moving Platform ◽  
Two Degree Of Freedom ◽  
Spherical Motion ◽  
Motion Generator

The present paper proposes the analysis of a spherical wrist with two degrees of freedom for scanning system applications. The wrist consists of two chains of revolute-revolute pairs. A slotted arc connecting the two chains behaves as a further revolute pair. Thus, the mechanism is an overconstrained (meaning of this definition is discussed in this work) single-loop kinematic chain composed of five revolute pairs equivalent to a spherical motion generator since all its axes intersect at a point. Throughout the paper, the kinematic analysis is developed including some details about the workspace, which depends on the design of the slotted arc. The performance index given as the inverse of the condition number is used to measure the performances of the motion of the moving platform of the wrist. The singularity poses found were examined in detail. A simplified dynamic model is proposed that provides the torques suitable for satisfying a given kinematics. Finally, the paper presents a motorized hardware model of the mechanism assembled in the laboratory.

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