Evolutionary based techniques are employed in order to overcome shortcomings of conventional optimization methods [2,8—10]。 GA and their variants are part of the evolutionary techniques and have been extensively used for modular robot design [I I—14], inverse and forward kinematics [9,15] and optimum motion and path planning [10, 16]。 DE is a recently developed evolutionary technique [17,18]。 DE has been successfully applied to the optimum design of digital filter and communication control [17], and according to information on the web [19] to many perse domains such as dynamic systems, controller design, heat transfer analysis and design, and many more。 The DE technique to the best of our knowledge has never been investigated or applied to the optimum design of serial link manipulators。
This article addresses the application and comparison of three evolutionary techniques for optimum design of serial link robotic manipulators based to task specifi- cations。 The objective function minimizes the required torque for a defined motion subject to various constraints while considering kinematic, dynamic and structural conditions。 The kinematic and dynamic analyses are derived based on robotic concepts and the structural analysis is performed based on the finite element method。 The design variables examined are the link parameters and the link cross-sectional characteristics。 The developed environment was employed in optimizing the design variables for a SCARA and an articulated 3-DOF PUMA type manipulators。
2。 OPTIMIZATION PROBLEM DEFINITION
The general optimization problem is defined as follows [20]
where f(:x) is the objective function, g;(x) is the set of inequality constraints and x o fi"is the real-valued design variable vector with n being the number of design variables。
The optimization problem investigated is that of optimizing the link parameters for a robotic manipulator to obtain minimum power requirements or joint torques。 The task specification is subpided into two elements, the kinematic characteristics (the required position of the end effector) and dynamic characteristics (the time required to complete the motion while carrying the payload and considering the inertia properties of the links themselves)。 Constraints are imposed on the minimum and maximum (range) values of the link parameters that include the link length, and the link cross-sectional area characteristics, and the allowable deflection of the end effector。 In addition, kinematics constraints are imposed that address physical limitations such as the range of motion of the actuators of the manipulator。
• Objective Function
The objective function is defined as the cumulative sum of the torques for each joint during the motion of the manipulator,
time joints
where /, is the torque at time i for joint j。
• Constraints
The constraints for this optimization include the deflection of the end effector of the manipulator, physical constraints such as the limits on the joint values, and the structural characteristics of each link。 Other constraints that could be included for the design of manipulators are quantitative measures of various workspace attributes such as manipulability or the structural length index。 机器人优化设计英文文献和中文翻译(2):http://www.youerw.com/fanyi/lunwen_82103.html