Design of adaptive neuro-fuzzy inference system for predicting surface roughness in turning operation

653-659This paper proposes an Adaptive Neuro-Fuzzy Inference System (ANFIS) for predicting the surface roughness in turning operation for set of given cutting parameters, namely cutting speed, feed rate and depth of cut. Two different membership functions, triangular and bell shaped, were adopted during the training process of ANFIS in order to compare the prediction accuracy of surface roughness by the two membership functions. The comparison of ANFIS values with experimental data indicates that the adoption of both triangular and bell shaped membership functions in proposed system achieved satisfactory accuracy. The bell-shaped membership function in ANFIS achieves slightly higher prediction accuracy than triangular membership function

An adaptive network-based fuzzy approach for prediction of surface roughness in CNC end milling

329-334An Adaptive Network-based Fuzzy Inference System (ANFIS) has been designed for modeling and predicting the surface roughness in end milling operation for set of three given milling parameters (spindle speed, feed rate and depth of cut). Two different membership functions (triangular and bell shaped) were used during the hybrid-training process of ANFIS in order to compare the prediction accuracy of surface roughness by the two membership functions. The predicted surface roughness values obtained from ANFIS were compared with experimental data and multiple regression analysis. The comparison indicates that the adoption of both membership functions in ANFIS achieved better accuracy than multiple regression model

Motion planning of planar and redundant underwater serial link manipulator based on minimization of energy consumption

The article describes motion planning of an underwater redundant manipulator with revolute joints moving in a plane under gravity and in the presence of obstacles. The proposed motion planning algorithm is based on minimization of the total energy in overcoming the hydrodynamic as well as dynamic forces acting on the manipulator while moving underwater and at the same time, avoiding both singularities and obstacle. The obstacle is considered as a point object. A recursive Lagrangian dynamics algorithm is formulated for the planar geometry to evaluate joint torques during the motion of serial link redundant manipulator fully submerged underwater. In turn the energy consumed in following a task trajectory is computed. The presence of redundancy in joint space of the manipulator facilitates selecting the optimal sequence of configurations as well as the required joint motion rates with minimum energy consumed among all possible configurations and rates. The effectiveness of the proposed motion planning algorithm is shown by applying it on a 3 degrees-of-freedom planar redundant manipulator fully submerged underwater and avoiding a point obstacle. The results establish that energy spent against overcoming loading resulted from hydrodynamic interactions majorly decides the optimal trajectory to follow in accomplishing an underwater task

Computer aided modeling and analysis of turning motion of hexapod robot on varying terrains

To successfully design a hexapod robot with maneuverability over varying terrains, the kinematic and dynamic analyses for its motion are very essential. This paper proposes an integrated approach for carrying out design, analysis and simulation of the motions and mechanisms of hexapod robots generating turning gaits. A new path planning approach is proposed for the turning motion analysis of the robot walking over any kind of terrain varying from flat to rough in three-dimensional Cartesian space with the desired gait pattern. The kinematics model of the hexapod robot having legs of three degrees of freedom each is developed to simulate turning motion, and its performance is tested on a realistic computer aided design model using the available virtual prototyping tools. The model is capable of investigating various kinematic parameters of the hexapod robot like displacement, velocity, acceleration, trace of the position of aggregate center of mass during turning motions. A case study is solved and the theoretically obtained results are verified by simulating the same in a commercially available numerical solver for multibody dynamic analysis like MSC.ADAMS®. The results show a close agreement between the theoretical and simulated results, which proves the efficacy of the proposed algorithm

Modeling and Simulation of Wave Gait of a Hexapod Walking Robot: A CAD/CAE Approach

In the present paper, an attempt has been made to carry out dynamic analysis of a hexapod robot using the concept of multibody dynamics. A CAD (Computer Aided Design) model of a realistic hexapod robot has been made for dynamic simulation of its locomotion using ADAMS (Automatic Dynamic Analysis of Mechanical Systems) multibody dynamics solver. The kinematic model of each leg of three degrees of freedom has been designed using CATIA (Computer Aided Three Dimensional Interactive Application) and SimDesigner package in order to develop an overall kinematic model of the robot, when it follows a straight path. Joint Torque variation as well as the variation of the aggregate center of mass of the robot was analyzed for the wave tetrapod gait. The simulation results provide the basis for developing the control algorithm as well as an intelligent decision making for the robot while in motion

Study on feet forces' distributions, energy consumption and dynamic stability measure of hexapod robot during crab walking

This paper deals with the development of a dynamical model related to crab walking of a hexapod robot to determine the feet forces' distributions, energy consumption and dynamic stability measure considering the inertial effects of the legs on the system, which has not been attempted before. Both forward and inverse kinematic analyses of the robot are carried out with an assigned fixed global frame and subsequent local frames in the trunk body and joints of each leg. Coupled multi-body dynamic model of the robot is developed based on free-body diagram approach. Optimal feet forces and corresponding joint torques on all the legs are determined based on the minimization of the sum of the squares of joint torques, using quadratic programming (QP) method. An energy consumption model is developed to determine the minimum energy required for optimal values of feet forces. To ensure dynamically stable gaits, dynamic gait stability margin (DGSM) is determined from the angular momentum of the system about the supporting edges. Computer simulations have been carried out to test the effectiveness of the developed dynamic model with crab wave gaits on a banking surface. It is observed that when the swing leg touches the ground, impact forces (sudden shoot outs) are generated and their effects are also observed on the joints of the legs. The effects of walking parameters, namely trunk body velocity, body stroke, leg offset, body height, crab angle etc. on power consumption and stability during crab motion for duty factors (DFs) like 1/2, 2/3, 3/4 have also been studied

Optimal Feet-Forces’ and Torque Distributions of Six-Legged Robot Maneuvering on Various Terrains

An analytical model with coupled dynamics for a realistic six-legged robotic system locomoting on various terrains has been developed, and its effectiveness has been proven through computer simulations and validated using virtual prototyping tools and real experiment. The approach is new and has not been attempted before. This study investigated the optimal feet-forces’ distributions under body force and foot–ground interaction considering compliant contact and friction force models for the feet undergoing slip. The kinematic model with 114 implicit constraints in 3D Cartesian space has been transformed in terms of generalized coordinates with a reduced explicit set of 24 constrained equations using kinematic transformations. The nonlinear constrained inverse dynamics model of the system has been formulated as a coupled dynamical problem using Newton–Euler method with realistic environmental conditions (compliant foot–ground contact, impact, and friction) and computed using optimization techniques due to its indeterminate nature. One case study has been carried out to validate the analytical data with the simulated ones executed in MSC.ADAMS® (Automated Dynamic Analysis of Mechanical Systems), while the other case study has been conducted to validate the analytical and simulated data with the experimental ones. In both these cases, results are found to be in close agreement, which proves the efficacy of the model

Design of an automatic parallel type jute bag making machine

93-96An attempt has been made to design a jute bag making machine in which all operations, like fabric cutting, hemming, mid-folding and herackle stitching, are carried out automatically in a single setup to produce parallel type jute bags of industrial standards. The salient design features of indigenously developed first prototype of an automatic jute bag making machine have been described. The proposed machine comprises four major units, like fabric cutting and conveying unit, simultaneous mouth edge folding and stitching unit, mid folding and material guidance unit, and simultaneous parallel side stitching unit. The motor drives, sensors and actuators are synchronized and automated by programmable logic controller. The proposed machine can produce bags of uniform quality with mouth edge folded, hemmed and parallel side stitched in one single integrated setup at higher productivity compared to present manual system