I.J. Modern Education and Computer Science, 2015, 1, 47-54 Published Online January 2015 in MECS (http://www.mecs-press.org/) DOI: 10.5815/ijmecs.2015.01.07 Copyright © 2015 MECS I.J. Modern Education and Computer Science, 2015, 1, 47-54 Improved PSO tuned Classical Controllers (PID and SMC) for Robotic Manipulator Neha Kapoor, Jyoti Ohri Department of Electrical Engineering, National Institute of Technology, Kurukshetra-136118 Email:ernehakapoor@rediffmail.com Abstract—Due to simplicity and robustness, classical PID and SMC have been still widely used in practical applications. Performance of these controllers (PID and SMC) depends upon the value of some of the constant controller parameters. To avoid the most commonly used tedious trial and error method, this paper proposes an improved PSO based method for getting the optimized value of these parameters. For validation purpose these improved PSO tuned Proportional Integral Derivative (PID) and Sliding Mode (SMC) classical controllers have been applied for the motion control problem of the robotic manipulator. The chattering problem of SMC has been handled by using pseudo sliding function. Further results have been analyzed by comparing them with the basic conventional controllers. Results and conclusions are based on simulation results. Index Terms—Non-linear control systems, Particle Swarm Optimization (PSO), Proportional Integral Derivative (PID), Sliding Mode Controller (SMC), Pseudo Sliding Function. I. INTRODUCTION Despite the success of modern control theory, Proportional Integral Derivative (PID) and Sliding Mode Controller (SMC) are the two earliest control techniques that are still used widely in almost all the industrial applications. This is because of their simplicity, easy to implement in hardware or software, and does not require a precise process model to start up and maintain and hence has invariance to parametric uncertainties [1-3]. Most crucial step for achieving a good performance t in PID and SMC is finding out the optimal values of the constant parameters. In PID controller, constants of the controllers have to have a higher value for good control action [4]; but also increasing their value can take the controller to the instability. In SMC, constant of switching function and exponential reaching law are important. In SMC,    ሺሻ ሺ    ሻ, [5] value of k should be small to eliminate chattering and should be kept large to increase the robustness of SMC. Increasing A can increase the reaching velocity but can cause chattering in SMC. With this discussion it can be said that for a good control performance the basic necessity is to get an optimal value of these parameters of PID and SMC. Tuning methods of classical controllers can be classified as traditional and intelligent methods. Traditional methods include Trial And Error (TAE) methods by which it is very hard to find the optimized tuned parameters. Also in contrast to intelligent methods, TAE tuning method is very time consuming and a frustrating job [jref]. Other than tuning problem, some other problems in SMC are discussed further. Firstly, the key technical problem of chattering in SMC is a challenging issue. Undesirable phenomenon of oscillations with finite frequency and amplitude around a predefined switching manifold is known as ‗chattering‘ [7]. This condition of chattering may worsen further if some unmodeled dynamics of the system comes into picture. Chattering can increase the controller burden and damage the controller parts. Secondly, the stage from initial state (i.e. reaching stage or non-sliding stage) to sliding state system is only a feedback controller and hence robustness of the system is weakened to a great extend [8]. In literature, many solutions like boundary layer solutions [9], continuous approximation method [10] and second and higher order SMC [11] have been proposed for chattering reduction. One of the boundary layer methods is to replace pure signum function of SMC with Pseudo Sliding Function [12]. Robotic manipulator is highly reliable and most commonly used advanced factory equipment these days. An n-link robotic manipulator is a complicated system with highly non-linear dynamics, strong coupling and the uncertainties in the dynamics like payload mass, disturbance and friction etc. Hence, it can be said that it is almost impossible to get an accurate mathematical model of a manipulator. Hence, the challenge is still to design an effective controller with accuracy and without the accurate knowledge of the system dynamics. One solution to the problem is to make the classical controllers intelligent. This can be achieved by introduction of intelligent agents to the classical controllers like PID and SMC. An intelligent technique like Particle Swarm Optimization (PSO) is capable to make smart optimizations in nature [13]. Hence, diffusion of intelligent techniques like PSO with PID [14-17] and SMC [18-22] has become a major research topic recently and achieved a lot of success in last few years. The rest of the paper is organized as follows-Section II describes the dynamics and the properties of the robotic