Tham khảo tài liệu 'motion control theory needed in the implementation of practical robotic systems 2 part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 5 Soft Computing nine possible rules so it is reasonable to use each rule. These rules are presented in a more compact form in Table . Table Weight Given to PID Controllers Torque Command. THEN the SMC s weight is. AND the Pendulum Velocity is. Small Medium Large IF the Pendulum Angle is. Small Small Medium Large Medium Medium Medium Large Large Large Large Large The basis of Fuzzy Logic is that the concepts of Small Medium and Large can represent fuzzy sets instead of crisp sets. There is no single value above which the pendulum angle is Large. Instead the angle has varying degrees of largeness that increase with the angle until it can be described as wholly large. In this example the angle and velocity are limited to a discrete Universe of Discord. The absolute values of pendulum angle and velocity are limited to 40 and 30 RPM respectively and discretized to one hundred distinct values. Each value is assigned an amount of smallness mediumness or largeness between zero and one. The output is also described in terms of a membership functions on an output universe of discord of zero to 100 percent use of the SMC s output. The input and output membership functions are illustrated in Figure . For creating the output universe of discord 100 discrete values are used but the resulting output is not rounded to the nearest whole value. There are 10 000 possible combinations of two inputs with 100 outputs so the entire input output space of the system can be stored as a look-up table with 10 000 outputs. Choosing 16 bit integers for 65 536 possible outputs provided adequate resolution in simulation and results in a 20 000 byte look-up table making it practical for implementation on a DSP. The surface mapped by this table is illustrated in Figure . 49 Chapter 5 Soft Computing 0 20 40 60 80 100 Figure . Input Angle and Velocity and Output Percent SMC Membership Functions Figure . This surface maps the input output behavior of the controller. 50 .
