Multi-legged Walking Machine Research Articles

Minimizing Energy Cost in Multi-Legged Walking Machines

Due to their ability to avoid obstacles and to move over difficult terrain, moreover having the ability to adjust their posture, walking machines for many years have been considered as very promising devices for inspection, exploration and surveyance tasks, however still they have not been widely applied. One of the main limitations is the power supply. Six legged walking machines are robust from the point of view of their walking stability in difficult terrain, but their actuators (18 if each leg has active 3 DOF’s) adds to their weight what increases the energy consumption. The higher energy consumption requires more efficient batteries, but usually those are heavier, what again increases the energy demand. Therefore at the design stage a detailed analysis is required of how to decrease the energy consumption. This paper studies energy consumption considering the tripod gait of hexapods. The method used for energy evaluation is presented and the results are discussed. The discussion of energy saving both for the leg transfer phase and during the support phase, which is the most demanding phase, is presented. The energy consumption is expressed in the normalized form, depending on the normalized leg proportions, body height and step length. The straight line forward/backward and side walking are analyzed. The aim of the studies is to provide to the designers the information about favorable leg proportions taking into account the reduction of required energy and to provide the information which leg posture should be selected.

Design of Multi-Legged Walking Machine

It is hard for normal traffic to travel on rugged road and polluted for the environment. So a new multi-legged walking machine with double mixed power is designed. The machine is made up of several parts, including mechanic walking part with eight legs, transmission part with two gears, two electric control footboards, two power motors and a folded beach umbrella. Detailed explanation of designed idea and process for mechanic walking legs is made. Detailed explanation of transmission ratio, circuit diagram and working principle for gear transmission is made as well. It makes simulation analysis for mechanic legs by software AUTODESK INVENTOR. The result shows that moving distance and strength are satisfied and meet standard.

Neural control of a modular multi-legged walking machine: Simulation and hardware

The modular walking machine Octavio is a bio-inspired robot designed to serve as a testbed for modular neural locomotion control. It consists of up to eight control- and energy-autonomous leg modules, each equipped with 3 active and 2 passive compliant joints and various proprioceptive sensors. Legs may be either used in single leg (treadmill) experiments or can be quickly attached to and detached from bodies with different morphologies. Body morphologies include 4-, 6- and 8-legged machines. Neurocybernetic control is developed and optimized using evolutionary techniques together with a physical simulation of the machine and its environment. This article gives an overview of the machines mechanics, electronics, firmware, configuration and control software. Simple examples demonstrate how the behavior of the simulated and the physical machines are controlled by e.g. neurobiologically motivated modular neural networks.

Trajectory Planning Realization for Multi-Legged Walking Machine's Leg

In this paper, multi-legged walking machine is simplified as one leg, which the whole machine is constructed by the modularization configuration of the legs in an axisymmetric way. Consequently, the control of one leg and its trajectory planning is the significant part for multi-legged walking machine. This paper, according to the structure of the walking machine's leg with 3-DOF open chains, calculates the terminal track of the leg using the principle of kinematics and presents a foot's controller based on dSPACE. In order to obtain the optimization of the foot's track, the three-cubic spline algorithm is considered. Depending on the model of the control system in Matlab, the paper provides a semi-physical simulation for a real leg using dSPACE. The feasibility of the planned track is demonstrated and the PID parameters have been adjusted.

Optimization of legged robot locomotion by control of foot-force distribution

The contribution of this paper is the introduction of three new pseudo-inverse formulations for the real-time control of foot-force distribution in multi-legged walking machines. Three alternative locomotion performance objectives are proposed for the purpose of optimizing the foot-force distribution. An exhaustive search method has been used to obtain truly optimal results, which are then used for comparison with the results obtained using suboptimal pseudo-inverse formulations that are suitable for real-time control. Simulation results show that, by using the appropriate pseudo-inverse formulation, a good approximation to the corresponding optimal foot-force distribution can be obtained. Furthermore, it is clear that the friction duty factor formulation provides an excellent real-time solution for minimizing the risk of foot-slip.

The novel approaches for computing the dynamic load-carrying capacity of multiple cooperating robotic manipulators

A novel unified method for computing the dynamic load-carrying capacity (DLCC) of multiple cooperating robotic manipulators is developed in this paper. In this method, the kinematic constraints and the governing dynamic equations of the multiple robot system are formulated in the joint space by using the method of transference of dependence from one set of generalized coordinates to another, and the generalized D'Alembert's principle (the Virtual Work principle), which includes the readily available dynamics and joint torques of individual manipulators, and the dynamic of payload. Based on this dynamic model, the upper limit of the DLCC at any points on a given trajectory is obtained by solving a small-size linear programming problem. This method is conceptually straightforward, and it is applicable also to the cases of multi-fingered robot hands and multi-legged walking machines.

Performance measures for constrained systems

We present a geometric theory of the performance of robot manipulators, applicable to systems with constraints, which may be nonholonomic. The performance is quantified by a geometrical object, the induced metric tensor, from which scalars may be constructed by invariant tensor operations to give performance measures. The measures thus defined depend on the metric structure of configuration and workspace, which should be chosen appropriately for the problem at hand. The generality of this approach allows us to specify a system of joint connected rigid bodies with a large class of metrics. We describe how the induced metric can be computed for such a system of joint connected rigid bodies and describe a MATLAB program that allows the automatic computation of the performance measures for such systems. We illustrate these ideas with some computations of measures for the SARCOS dextrous arm, and the Platonic Beast, a multilegged walking machine.

The Mechanics of Parallel Mechanisms and Walking Machines

A parallel mechanism is one whose links and joints form two or more serially connected chains which join the fixed base and the end effector The mechanism of a multi-legged walking machine can be considered as a parallel mechanism whose base is not fixed and whose configuration changes during different phases of its gait. This paper presents methods for analysing the mechanics of parallel mechanisms and walking machines using vector and screw algebra Firstly, displacement analysis is covered; this includes general methods for deriving the position vector of any joint in any leg and for calculating the active joint displacements in any leg. Secondly, velocity analysis is covered which tackles the problem of calculating active joint velocities given the velocity, position and the orientation of the body and the positions of the feet. Thirdly, the static analysis of these classes of mechanisms using the principle of virtual work and screw algebra is given. Expressions are derived for the actuator forces and torques required to balance a given end effector (or body) wrench and, in the case of a walking machine, the ground reactions at the feet. Numerical examples are given to demonstrate the application of these methods.

Basic Design and Synchronized Motion Control for Hexapod Walking Machine

This paper discusses a new mechanism and a new method of motion control for a multi-legged walking machine. The new mechanism provides high energy efficiency which is one of the most important points of walking machines. This problem is solved combining a gasoline engine and an electromagnetic clutch system. In addition, synchronized motion control is also proposed for this mechanism. This control is based on the notion of an autonomous distributed control. Thus, this system has sufficient flexibility and reliability.

An adaptive gait for legged walking machines over rough terrain

An adaptive gait algorithm for multilegged walking machines over rough terrain has been developed. The heuristic and hierarchical approach for the three levels of: 1) body motion adaptation; 2) leg sequence adaptation; and 3) leg position adaptation is effective, straightforward, and relatively independent of the number of legs. On rough terrains with depressions the algorithm behaves like a free gait; on level ground terrain it behaves more like a periodic gait. The effectiveness of the proposed gait over rough terrains with depressions is demonstrated with several computer simulations. >

Dynamic Simulation of Legged Machines Using a Compliant Joint Model

A computerized simulation of the dynamics of multilegged walking machines is presented. The simulation includes the effects of leg mass and compliance, joint compliance and friction, as well as the effects of leg contact with the ground. An approach is presented in which the Newton-Euler formu lation is used to develop the dynamic equations of each link. Kinematic constraints are not imposed explicitly. Instead, a compliant joint model is used to relate the dynamic reaction forces between neighboring links. The approach can handle multiloop devices with a combination of closed and open kinematic chains. Simulation results for the Ohio State Uni versity Hexapod walking machine are presented and shown to be in close agreement with previously published experi mental data.

Dynamic Simulation of Legged Machines Using a Compliant Joint Model

A computerized simulation of the dynamics of multilegged walking machines is presented. The simulation includes the effects of leg mass and compliance, joint compliance and friction, as well as the effects of leg contact with the ground. An approach is presented in which the Newton-Euler formu lation is used to develop the dynamic equations of each link. Kinematic constraints are not imposed explicitly. Instead, a compliant joint model is used to relate the dynamic reaction forces between neighboring links. The approach can handle multiloop devices with a combination of closed and open kinematic chains. Simulation results for the Ohio State Uni versity Hexapod walking machine are presented and shown to be in close agreement with previously published experi mental data.