Body Vibration of a Legged Walking Machine

1993 ◽  
Vol 115 (4) ◽  
pp. 856-862
Author(s):  
Xiaochun Gao ◽  
Shin-Min Song
Keyword(s):  
The Body ◽  
Robotic Systems ◽  
Force Distribution ◽  
Walking Machine ◽  
Foot Force ◽  
Robot Hands ◽  
Machine Systems ◽  
External Loads ◽  
Wheeled Vehicles ◽  
Quadrupedal Walking

Unlike wheeled vehicles, compliance in walking machine systems changes due to the variation of leg geometry, as its body proceeds. This variation in compliance will cause vibration, even if external loads remain constant. A theory is thus developed to predict the body vibrations of a walking machine during walking. On the other hand, dynamic foot forces under body vibrations can be computed by application of the existing numerical methods. As an example, the body vibrations of a quadrupedal walking chair under different walking conditions are simulated in terms of the developed theory. The results show that the influence of body vibrations on the foot force distribution is essential and, in some cases, the walking chair may lose its stability due to its body vibrations, even though it is identified to be stable in a quasistatic analysis. The developed theory can also be extended to other similar multilimbed robotic systems, such as multifingered robot hands.

Body Vibrations of a Legged Walking Machine

1992 ◽  
Author(s):  
Xiaochun Gao ◽  
Shin-Min Song
Keyword(s):  
The Body ◽  
Robotic Systems ◽  
Force Distribution ◽  
Walking Machine ◽  
Foot Force ◽  
Robot Hands ◽  
Machine Systems ◽  
External Loads ◽  
Wheeled Vehicles ◽  
Quadrupedal Walking

Abstract Unlike in wheeled vehicles, compliance in walking machine systems changes due to the variation of leg geometry, as its body proceeds. This variation in compliance will cause vibration, even if external loads remain constant. A theory is thus developed to predict the body vibrations of a walking machine during walking. On the other hand, dynamic foot forces under body vibrations can be computed by application of the existing numerical methods. As an example, the body vibrations of a quadrupedal walking chair under different walking conditions are simulated in terms of the developed theory. The results show that the influence of body vibrations on the foot force distribution is essential and, in some cases, the walking chair may lose its stability due to its body vibrations, even though it is identified to be stable in a quasi-static analysis. The developed theory can also be extended to other similar multi-limbed robotic systems, such as multi-fingered robot hands.

Foot force distribution of walking machine with consideration of terrain properties

1992 ◽  
Vol 29 (4-5) ◽  
pp. 497-514 ◽  
Author(s):  
Chun Qi Zheng ◽  
Shin-Min Song ◽  
G.E.O. Widera
Keyword(s):  
Force Distribution ◽  
Walking Machine ◽  
Foot Force

An efficient foot-force distribution algorithm for quadruped walking robots

Robotica ◽  
2000 ◽  
Vol 18 (4) ◽  
pp. 403-413 ◽  
Author(s):  
Debao Zhou ◽  
K. H. Low ◽  
Teresa Zielinska
Keyword(s):  
Force Control ◽  
Computation Time ◽  
Optimization Method ◽  
The Body ◽  
Walking Robots ◽  
Force Distribution ◽  
Active Force ◽  
Distribution Method ◽  
Walking Machine ◽  
Active Force Control

One of the important issues of walking machine active force control is a successful distribution of the body force to the feet to prevent leg slippage. In this paper, a new force distribution method, the Friction Constraint Method (FriCoM), is introduced. The force distribution during the walking of a typical quadruped crawl gait is analyzed by using the FriCoM. Computation results show that the distributed forces of the feet are continuous during the walking. This reflects the change of the force distribution during actual conditions. The comparison with a pseudo-inverse method shows that the FriCoM is more practical. The FriCom also requires less computation time than that by an incremental optimization method. Some problems, such as the singularity in the application of the FriCoM, are discussed. The FriCoM will be used in the active force control of a quadruped robot that is taken as a platform for the research on the study of terrain adaptation.

A Solution for the Force Distribution Problem in Redundantly Actuated Closed Kinematic Chains

1990 ◽  
Vol 112 (3) ◽  
pp. 523-526 ◽  
Author(s):  
J. F. Gardner ◽  
K. Srinivasan ◽  
K. J. Waldron
Keyword(s):  
System Performance ◽  
Additional Constraint ◽  
Robotic Systems ◽  
Force Distribution ◽  
Distribution Problem ◽  
Walking Machine ◽  
Kinematic Chains ◽  
Constraint Equations ◽  
Redundantly Actuated ◽  
Alternative Solutions

Proper control of robotic systems which incorporate closed kinematic chains is important in many applications. Among these are the multi-robot work cell and legged vehicles. In these no unique solution exists for the force distribution corresponding to a specified trajectory. A framework within which additional constraint equations may be written is presented here, and the force distribution solved in closed form for a walking machine application. These constraints are related to system performance goals of interest, such as improved traction and/or load sharing among the legs. The proposed technique is shown to be computationally simpler than other alternative solutions to the same problem.

A Study of Fuzzy-Neural Force Control for a Quadrupedal Walking Machine

1998 ◽  
Vol 120 (1) ◽  
pp. 124-133 ◽  
Author(s):  
Chau-Ren Tsai ◽  
Tsu-Tian Lee
Keyword(s):  
Fuzzy Logic ◽  
Degrees Of Freedom ◽  
Fuzzy Logic Controller ◽  
High Efficiency ◽  
Weight Ratio ◽  
Planetary Gear ◽  
Walking Machine ◽  
Foot Force ◽  
Compact Size ◽  
Quadrupedal Walking

In this paper, the inverse kinematics and the foot force distributions of a planetary gear type quadrupedal walking machine are analyzed. This walking machine has four legs and each leg has three-degrees-of-freedom. The whole system has a total of seventeen links. The planetary gear leg is designed for a quadruped which can walk and trot under the following design criteria: high efficiency, compact size, and high payload/weight ratio. A neural network structure fuzzy logic controller is applied to control the foot force distribution of the quadruped walking machine. The performance of this fuzzy logic control algorithm is evaluated. Experimental results show that the fuzzy logic controller is effective in controlling this walking machine.

A Generalized Stiffness Matrix Method for Force Distribution of Robotic Systems with Indeterminancy

1993 ◽  
Vol 115 (3) ◽  
pp. 585-591 ◽  
Author(s):  
Xiaochun Gao ◽  
Shin-Min Song ◽  
Chun Qi Zheng
Keyword(s):  
Stiffness Matrix ◽  
Matrix Method ◽  
Robotic Systems ◽  
Force Distribution ◽  
Force Analysis ◽  
Chain Geometry ◽  
Walking Machines ◽  
Foot Force ◽  
Closed Chain ◽  
Finger Forces

Foot forces in walking machines and finger forces in multi-fingered grippers are usually indeterminate due to the multi-closed-chain geometry of the systems. While many methods were proposed to solve the force distribution of such systems, a method called stiffness matrix method [2] was developed based on the concept that the force must satisfy the equations of material deformations. However, only leg compliances were considered in the stiffness matrix method. In this paper, the stiffness matrix method is generalized to include all the major system compliances, i.e., those of legs (fingers), actuators and terrain (object to be grasped). Based on the developed generalized stiffness matrix method, an example of foot force analysis of a quadruped is presented to demonstrate the effects of different system compliances on the foot forces.

Leg Lift During Non-Overconstrained Pseudo-Static Walking

1996 ◽  
Author(s):  
Chee K. Foo ◽  
Eugene F. Fichter ◽  
Becky L. Fichter
Keyword(s):  
Position Control ◽  
The Body ◽  
Degree Of Freedom ◽  
Walking Machine

Abstract A non-overconstrained pseudo-static walking machine has 1 leg joint under position control for every degree-of-freedom of the body. When 1 joint is position controlled on each of 6 legs, leg lift during a step results in 1 unregulated degree-of-freedom of the body. A second joint in one of the 5 legs that maintain contact with the ground must be switched to active position control at the same time that a foot is lifted. In theory any passively controlled joint in the 5 supporting legs may be chosen. However the requirement that no leg be in tension and practical limits on torques available from joint actuators severely restrict choice of both additional joint to actively position control and possible body positions where legs can be lifted.

Walking Machine Design Based on Certain Aspects of Insect Leg Design

1992 ◽  
Author(s):  
E. F. Fichter ◽  
D. R. Kerr
Keyword(s):  
Control System ◽  
Observational Data ◽  
The Body ◽  
Static Equilibrium ◽  
Machine Design ◽  
Ground Contact ◽  
Careful Attention ◽  
Equilibrium Equations ◽  
Walking Machine ◽  
Leg Design

Abstract A walking machine design originating from observations of insects is presented. The primary concept derived from insects is a leg used to apply force to the body without applying significant moments about the point of body attachment. This is accomplished with legs which have kinematic equivalents to ball-and-socket joints at body attachment and ground contact, with joints in the middle which only change distance between body and ground. Standing and walking with 6 legs of this design requires careful attention to static equilibrium equations but does not necessitate a control system which actively distributes forces to the legs. This paper considers necessary observational data, assumptions on which control is based, mathematical development for control and problems such as foot slip.

scholarly journals Load carriage, human performance, and employment standards

2016 ◽  
Vol 41 (6 (Suppl. 2)) ◽  
pp. S131-S147 ◽  
Author(s):  
Nigel A.S. Taylor ◽  
Gregory E. Peoples ◽  
Stewart R. Petersen
Keyword(s):  
Work Performance ◽  
Human Performance ◽  
Performance Testing ◽  
The Body ◽  
Load Carriage ◽  
Physical Endurance ◽  
Physiological Strain ◽  
Employment Standards ◽  
Heavy Loads ◽  
External Loads

The focus of this review is on the physiological considerations necessary for developing employment standards within occupations that have a heavy reliance on load carriage. Employees within military, fire fighting, law enforcement, and search and rescue occupations regularly work with heavy loads. For example, soldiers often carry loads >50 kg, whilst structural firefighters wear 20–25 kg of protective clothing and equipment, in addition to carrying external loads. It has long been known that heavy loads modify gait, mobility, metabolic rate, and efficiency, while concurrently elevating the risk of muscle fatigue and injury. In addition, load carriage often occurs within environmentally stressful conditions, with protective ensembles adding to the thermal burden of the workplace. Indeed, physiological strain relates not just to the mass and dimensions of carried objects, but to how those loads are positioned on and around the body. Yet heavy loads must be borne by men and women of varying body size, and with the expectation that operational capability will not be impinged. This presents a recruitment conundrum. How do employers identify capable and injury-resistant individuals while simultaneously avoiding discriminatory selection practices? In this communication, the relevant metabolic, cardiopulmonary, and thermoregulatory consequences of loaded work are reviewed, along with concomitant impediments to physical endurance and mobility. Also emphasised is the importance of including occupation-specific clothing, protective equipment, and loads during work-performance testing. Finally, recommendations are presented for how to address these issues when evaluating readiness for duty.

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