Design and Implementation of a Leg–Wheel Robot: Transleg

2017 ◽  
Vol 9 (5) ◽  
Author(s):  
Zhong Wei ◽  
Guangming Song ◽  
Guifang Qiao ◽  
Ying Zhang ◽  
Huiyu Sun
Keyword(s):  
Degrees Of Freedom ◽  
Legged Locomotion ◽  
The Body ◽  
Transmission Mechanism ◽  
Design And Implementation ◽  
Kinematic Analyses ◽  
Turning Motion ◽  
The Wire ◽  
The Stability ◽  
Bounding Gait

In this paper, the design and implementation of a novel leg–wheel robot called Transleg are presented. Transleg adopts the wire as the transmission mechanism to simplify the structure and reduce the weight. To the best knowledge of the authors, the wire-driven method has never been used in the leg–wheel robots, so it makes Transleg distinguished from the existing leg–wheel robots. Transleg possesses four transformable leg–wheel mechanisms, each of which has two active degrees-of-freedom (DOFs) in the legged mode and one in the wheeled mode. Two actuators driving each leg–wheel mechanism are mounted on the body, so the weight of the leg–wheel mechanism is reduced as far as possible, which contributes to improving the stability of the legged locomotion. Inspired by the quadruped mammals, a compliant spine mechanism is designed for Transleg. The spine mechanism is also actuated by two actuators to bend in the yaw and pitch directions. It will be beneficial to the turning motion in the legged and wheeled modes and the bounding gait in the legged mode. The design and kinematic analyses of the leg–wheel and spine mechanisms are presented in detail. To verify the feasibility of Transleg, a prototype is implemented. The experiments on the motions in the legged and wheeled modes, the switch between the two modes, and the spine motions are conducted. The experimental results demonstrate the validity of Transleg.

Rolling Condition and Gyroscopic Moments in Curve Negotiations

2012 ◽  
Author(s):  
Ahmed A. Shabana ◽  
Martin B. Hamper ◽  
James J. O’Shea
Keyword(s):  
Coordinate System ◽  
Degrees Of Freedom ◽  
The Body ◽  
Contact Forces ◽  
Body Motion ◽  
Global Coordinate System ◽  
Gyroscopic Moment ◽  
Absolute Angular Velocity ◽  
Pure Rolling ◽  
The Stability

In vehicle system dynamics, the effect of the gyroscopic moments can be significant during curve negotiations. The absolute angular velocity of the body can be expressed as the sum of two vectors; one vector is due to the curvature of the curve, while the second vector is due to the rate of changes of the angles that define the orientation of the body with respect to a coordinate system that follows the body motion. In this paper, the configuration of the body in the global coordinate system is defined using the trajectory coordinates in order to examine the effect of the gyroscopic moments in the case of curve negotiations. These coordinates consist of arc length, two relative translations and three relative angles. The relative translations and relative angles are defined with respect to a trajectory coordinate system that follows the motion of the body on the curve. It is shown that when the yaw and roll angles relative to the trajectory coordinate system are constrained and the motion is predominantly rolling, the effect of the gyroscopic moment on the motion becomes negligible, and in the case of pure rolling and zero yaw and roll angles, the generalized gyroscopic moment associated with the system degrees of freedom becomes identically zero. The analysis presented in this investigation sheds light on the danger of using derailment criteria that are not obtained using laws of motion, and therefore, such criteria should not be used in judging the stability of railroad vehicle systems. Furthermore, The analysis presented in this paper shows that the roll moment which can have a significant effect on the wheel/rail contact forces depends on the forward velocity in the case of curve negotiations. For this reason, roller rigs that do not allow for the wheelset forward velocity cannot capture these moment components, and therefore, cannot be used in the analysis of curve negotiations. A model of a suspended railroad wheelset is used in this investigation to study the gyroscopic effect during curve negotiations.

scholarly journals Investigation of the dynamic stability of bending-torsional deformations of the pipeline

2021 ◽  
Vol 23 (1) ◽  
pp. 72-81
Author(s):  
Petr A. Velmisov ◽  
Yuliya A. Tamarova ◽  
Yuliya V. Pokladova
Keyword(s):  
Dynamic Stability ◽  
Degrees Of Freedom ◽  
Deformable Body ◽  
Nonlinear Partial Differential Equations ◽  
Bending Moment ◽  
The Body ◽  
Initial Moment ◽  
Torsional Vibrations ◽  
Small Deviations ◽  
The Stability

Nonlinear mathematical models are proposed that describe the dynamics of a pipeline with a fluid flowing in it: a) the model of bending-torsional vibrations with two degrees of freedom; b) the model describing flexural-torsional vibrations taking into account the nonlinearity of the bending moment and centrifugal force; c) the model that takes into account joint longitudinal, bending (transverse) and torsional vibrations. All proposed models are described by nonlinear partial differential equations for unknown strain functions. To describe the dynamics of a pipeline, the nonlinear theory of a rigid deformable body is used, which takes into account the transverse, tangential and longitudinal deformations of the pipeline. The dynamic stability of bending-torsional and longitudinal-flexural-torsional vibrations of the pipeline is investigated. The definitions of the stability of a deformable body adopted in this work correspond to the Lyapunov concept of stability of dynamical systems. The problem of studying dynamic stability, namely, stability according to initial data, is formulated as follows: at what values of the parameters characterizing the gas-body system, small deviations of the body from the equilibrium position at the initial moment of time will correspond to small deviations and at any moment of time. For the proposed models, positive definite functionals of the Lyapunov type are constructed, on the basis of which the dynamic stability of the pipeline is investigated. Sufficient stability conditions are obtained that impose restrictions on the parameters of a mechanical system.

scholarly journals Bionic Control of Cheetah Bounding with a Segmented Spine

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Chunlei Wang ◽  
Shigang Wang
Keyword(s):  
Control Method ◽  
Dynamic Properties ◽  
Biological Properties ◽  
The Body ◽  
Body Balance ◽  
Feedback Control Method ◽  
Dimensional Parameters ◽  
Delay Feedback Control ◽  
The Stability ◽  
Bounding Gait

A cheetah model is built to mimic real cheetah and its mechanical and dimensional parameters are derived from the real cheetah. In particular, two joints in spine and four joints in a leg are used to realize the motion of segmented spine and segmented legs which are the key properties of the cheetah bounding. For actuating and stabilizing the bounding gait of cheetah, we present a bioinspired controller based on the state-machine. The controller mainly mimics the function of the cerebellum to plan the locomotion and keep the body balance. The haptic sensor and proprioception system are used to detect the trigger of the phase transition. Besides, the vestibular modulation could perceive the pitching angle of the trunk. At last, the cerebellum acts as the CPU to operate the information from the biological sensors. In addition, the calculated results are transmitted to the low-level controller to actuate and stabilize the cheetah bounding. Moreover, the delay feedback control method is employed to plan the motion of the leg joints to stabilize the pitching motion of trunk with the stability criterion. Finally, the cyclic cheetah bounding with biological properties is realized. Meanwhile, the stability and dynamic properties of the cheetah bounding gait are analyzed elaborately.

Posture Control of a Reconfigurable Mobile Vehicle with Legged Mode

2014 ◽  
Vol 541-542 ◽  
pp. 1049-1052
Author(s):  
Jian Ying Tian ◽  
Pei Yu Li ◽  
Ya Ping Li ◽  
Hong Hua Zhao
Keyword(s):  
Legged Locomotion ◽  
The Body ◽  
Posture Control ◽  
Stable Operation ◽  
Mobile Vehicle ◽  
Optimization Control ◽  
Vision Control ◽  
Kinematic Modelling ◽  
The Stability

Aiming at the moving requests of the miniature mobile vehicle under the environment of indoors and outdoors, A small track-wheel-legged mobile vehicle was developed in this paper. Many desired locomotion modes such as wheeled, tracked and legged locomotion can be realized by utilizing its independently actuated arms up and down. In order to have good adaptability, high maneuverability of obstacle negotiation and high locomotion security, the kinematic modelling was described, kinematic equations were derived, and optimization control was realized based on the analysis of the stability characteristics with wheel-legged locomotion, which can realize the posture control of mobile vehicle, so that the vehicle has the abilities of maintaining relatively stability of the body over uneven ground,. and these abilities are of great significance to stable operation and vision control of the vehicle.

scholarly journals Passive Dynamic Bounding Control using Symmetry Condition Control Laws

2019 ◽  
pp. 451-457
Author(s):  
P. Murali Krishna ◽  
R. Prasanth Kumar
Keyword(s):  
Fixed Points ◽  
Initial Conditions ◽  
Legged Locomotion ◽  
Zero Energy ◽  
Additional Energy ◽  
Control Laws ◽  
Quadruped Robots ◽  
Existence And Stability ◽  
The Stability ◽  
Bounding Gait

Legged locomotion is preferred over the wheeled locomotion as it can be used both for flat and rough terrains. Quadruped robots are preferred since they can offer better stability with considerable reliability. In recent years, passive dynamics has been used to obtain near zero-energy bounding gaits. Although theoretically such gaits consume no energy, in practice some additional energy is required to overcome losses. Existence and stability of such gaits have been thoroughly studied in literature for quadruped models with the assumption that the mass distribution and stiffness in the front and back legs are symmetric. Fixed points found using Poincare map indicate touchdown angle-liftoff angle symmetry between front and back legs. This property can be used to search for fixed points with ease. However, the range of initial conditions where the bounding gait is stable is highly limited. Control laws based on symmetry conditions observed are proposed in this paper to improve the stability region. One such control law based on body-fixed touchdown angles theoretically allows redesign of quadruped robot with physical cross coupling between legs to achieve inherent stability without leg actuation.

Kinematics of the knee joint

2012 ◽  
Vol 2 (3) ◽  
pp. 353-359
Author(s):  
W. Sampers ◽  
T. Sierens
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
The Body ◽  
Linear Actuator ◽  
Test Rig ◽  
Q Angle ◽  
The Stability ◽  
Near Future ◽  
Patella Tracking ◽  
Knee Rig

In 2006 a test rig was built by Ghent University to measure patellofemoral pressures. The maingoal of the current study is to improve and upgrade the Ghent Knee Rig (GKR). The improvement consistsof a better approach of the Q angle. The mechanical connection between the linear actuator and the rectusfemoris tendon represents the force of the quadriceps. To validate the results of measurement, it isnecessary the connection approaches the direction of the real muscle. The patella is bond with the body byuse of ligaments and retinacula, which have a unknown influence on the stability of the patella. Alsoquadriceps and the trochlea are important stabilizers. The upgrade of the GKR is a tool to measure thepatella stability, which is done by pulling the patella out of the trochlea and measure the force needed for acertain displacement. It is important the patella has five degrees of freedom (DOF) so no extra force but thestability is measured and the effect of dysplasia and trochleoplasty can be examined. In the near future theGKR will be expanded to the possibility of measuring patella tracking. The relative movements of thedifferent components of the knee will be followed by high speed cameras.

Rolling Condition and Gyroscopic Moments in Curve Negotiations

2012 ◽  
Vol 8 (1) ◽  
Author(s):  
Ahmed A. Shabana ◽  
Martin B. Hamper ◽  
James J. O’Shea
Keyword(s):  
Coordinate System ◽  
Degrees Of Freedom ◽  
Rate Of Change ◽  
The Body ◽  
Contact Forces ◽  
Body Motion ◽  
Global Coordinate System ◽  
Gyroscopic Moment ◽  
Absolute Angular Velocity ◽  
The Stability

In vehicle system dynamics, the effect of the gyroscopic moments can be significant during curve negotiations. The absolute angular velocity of the body can be expressed as the sum of two vectors; one vector is due to the curvature of the curve, while the second vector is due to the rate of change of the angles that define the orientation of the body with respect to a coordinate system that follows the body motion. In this paper, the configuration of the body in the global coordinate system is defined using the trajectory coordinates in order to examine the effect of the gyroscopic moments in the case of curve negotiations. These coordinates consist of arc length, two relative translations, and three relative angles. The relative translations and relative angles are defined with respect to a trajectory coordinate system that follows the motion of the body on the curve. It is shown that when the yaw and roll angles relative to the trajectory coordinate system are constrained and the motion is predominantly rolling, the effect of the gyroscopic moment on the motion becomes negligible and, in the case of pure rolling and zero yaw and roll angles, the generalized gyroscopic moment associated with the system degrees of freedom becomes identically zero. The analysis presented in this investigation sheds light on the danger of using derailment criteria that are not obtained using laws of motion and, therefore, such criteria should not be used in judging the stability of railroad vehicle systems. Furthermore, the analysis presented in this paper shows that the roll moment, which can have a significant effect on the wheel/rail contact forces, depends on the forward velocity in the case of curve negotiations. For this reason, roller rigs that do not allow for the wheelset forward velocity cannot capture these moment components and, therefore, should not be used in the analysis of curve negotiations. A model of a suspended railroad wheelset is used in this investigation to study the gyroscopic effect during curve negotiations.

Representing utility and deploying the body

2020 ◽  
Vol 43 ◽  
Author(s):  
David Spurrett
Keyword(s):  
Functional Activity ◽  
Degrees Of Freedom ◽  
The Body ◽  
Target Article ◽  
Processing Demands ◽  
The Many

Abstract Comprehensive accounts of resource-rational attempts to maximise utility shouldn't ignore the demands of constructing utility representations. This can be onerous when, as in humans, there are many rewarding modalities. Another thing best not ignored is the processing demands of making functional activity out of the many degrees of freedom of a body. The target article is almost silent on both.

THE CHARACTERISTICS OF ARTIFICIAL RICE WITH SEAWEED Eucheuma cottonii ADDITION AS A DIETARY FIBER SOURCE

2014 ◽  
Vol 6 (1) ◽  
Author(s):  
Natalia Prodiana Setiawati ◽  
Joko Santoso ◽  
Sri Purwaningsih
Keyword(s):  
Blood Glucose ◽  
Dietary Fiber ◽  
Dietary Fibre ◽  
Extrusion Process ◽  
The Body ◽  
Starch Digestibility ◽  
Food Commodities ◽  
The Stability ◽  
Extrusion Technology ◽  
Eucheuma Cottonii

The utilization of local food commodities such as corn and cassava with seaweed addition as a dietary fiber source for producing artificial rice through extrusion technology is an  alternative for food diversification. The research was carried out to find out the best composition (rice, corn, cassava, and seaweed) and temperature of extrusion process on making artificial rice and the influence of dietary fibre on sensory properties and physicochemical. The composition of rice, corn, and cassava in proportion  of 1:3:1 with 20% seaweed, Eucheuma cottonii, addition and temperature extruder of 90 °C were selected as the best product for artificial rice. The  sensory evaluation was 8.02±0.21 (people’s preference). In physicochemical properties, dietary fiber significantly affected on low bulk density and starch digestibility. This condition is very good for health especially in maintaining the stability of blood glucose in the body. Keywords: artificial rice, composition, extrusion, seaweed, dietary fibre, temperature

Substantiation the machine with a basket for the application of mineral fertilizers and other bulk materials with the upper arrangement of the feeding device

2019 ◽  
pp. 37-43
Author(s):  
Fesenko, H.
Keyword(s):  
Fat Body ◽  
Mineral Fertilizer ◽  
The Body ◽  
Mineral Fertilizers ◽  
Analytical Mechanics ◽  
Bulk Materials ◽  
The Stability ◽  
Working Bodies ◽  
The Relationship ◽  
Stable Flow

Purpose. Increasing the uniformity of distribution of mineral fertilizers and other bulk materials due to the stability of their feed from the body to the spreading working bodies using the top feeder. Methods. The following methods are used to achieve this aim: the method of comparing the differences between individual groups of fertilizers, the method of analyzing the properties of a new technical system, the method of functional inventiveness, and the methods of theoretical and analytical mechanics. Results. The traction body of the conveyor of the upper feed of the body fat body machine for mineral fertilizers and other bulk materials was substantiated and the relationship between the height of its scrapers and the distance between them was established, as well as the nature of the mineral fertilizer pressure on the curvilinear wall of the body. In addition, the design of the advanced body fertilizer spreader is justified, which ensures a stable flow of fertilizers from the body due to the improvement of the top feeder. Conclusions. Because of the conducted researches, the advantages of machines equipped with top feeder are found. They create the conditions for the forced feeding mineral fertilizers and other loose materials from the container to the distribution bodies, which is a prerequisite for their evenness on the surface. With this, the imperfection of known machines with the top feeder constrains their introduction into agricultural production. On this account, a more thoroughly constructed solution of the body feeder of the top feed is substantiated, in which the conveyor provides a stable supply of fertilizers from the body with reduced energy consumption during operation. Keywords: analysis, feed, upper device, conveyor, stability, fertilizers, flow ability, body.

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