FUNCTION_BLOCK ip    // Block definition (there may be more than one block per file)

VAR_OUTPUT            // Define input variables
    force : REAL;
END_VAR

VAR_INPUT           // Define output variable
    x : REAL;
    dxdt : REAL;
    phi : REAL;
    dphidt : REAL;
END_VAR

FUZZIFY x           
    TERM ok := ( -2, 0) (0,1) (2,0); 
    TERM left  :=  (-2,1)  (0,0);
    TERM right := (  0, 0) (2,1) ;
END_FUZZIFY

FUZZIFY dxdt        
    TERM  ok :=  (-10, 0) (0, 1) (5,0) ;
    TERM  left := (-10,1) (0,0);
    TERM  right := (0,0) (10,1) ;
END_FUZZIFY

FUZZIFY phi            
    TERM ok  := (-1,0) (0,1) (1,0);
    TERM left := (0,0) (1,1) ;
    TERM right :=  (-1,1) (0,0);
END_FUZZIFY

FUZZIFY dphidt            
    TERM ok  := (-10,0) (0,1) (10,0);
    TERM left := (0,0) (10,1) ;
    TERM right :=  (-10,1) (0,0);
END_FUZZIFY


DEFUZZIFY force          
    TERM zero  :=   (-1,0) (0,1) (1,0);
    TERM left  :=  (-201,0) (-200,1) (-199,0);
    TERM right :=  (199,0) (200,1) (201,0);

    METHOD : COG;        // Use 'Center Of Gravity' defuzzification method
    DEFAULT := 0;          // Default value is 0 (if no rule activates defuzzifier)
END_DEFUZZIFY

RULEBLOCK No1
    AND : MIN;     
    ACT : MIN;     
    ACCU : MAX;    

    RULE 1 : IF phi IS right AND dphidt IS right THEN force IS right ;
    RULE 2 : IF phi IS left  AND dphidt IS left  THEN force IS left  ;
    RULE 3 : IF phi IS ok AND dphidt IS ok THEN force IS zero ;

  //  RULE 3 : IF x   IS ok AND dxdt IS ok AND phi IS ok  AND dphidt IS ok    THEN force IS zero  ;
  //  RULE 4 : IF x   IS  right  AND dxdt IS ok AND phi    IS right THEN force IS right ;
   // RULE 5 : IF x   IS  left   AND dxdt IS ok AND phi    IS left THEN force IS left  ;
  //  RULE 6 : IF x   IS  ok AND dxdt IS right THEN force  IS left ;
   // RULE 7 : IF x   IS  ok AND dxdt IS left THEN force   IS right ;

END_RULEBLOCK

END_FUNCTION_BLOCK