Walking robot leg mechanism

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#include <Servo.h> Servo m1; Servo m2; Servo m3; Servo m4; int pos; int pos2; int pos3; int pos4; int a; int b; void setup() { m1.attach(9); m2.attach(10); m3.attach(11); m4.attach(12); delay(2000); m1.write(150); m2.write(90); m3.write(150); m4.write(90); } void loop() { pos=150; pos2=90; pos3=150; pos4=90; for (a = 0; a <= 60; a += 1) // goes to 0 degrees to 180 degrees { pos -=1; pos3 -=1; pos4 +=1; m1.write(pos); m3.write(pos3); m4.write(pos4); delay(10); // you can change the speed of motor by changing the value of delay } for (a = 0; a <= 60; a += 1) // goes to 0 degrees to 180 degrees { pos -=1; pos3 -=1; pos4 -=1; m1.write(pos); m3.write(pos3); m4.write(pos4); delay(10); // you can change the speed of motor by changing the value of delay } for (a = 0; a <= 60; a += 1) // goes to 0 degrees to 180 degrees { pos +=1; pos2 -=1; pos3 +=1; m1.write(pos); m2.write(pos2); m3.write(pos3); delay(10); // you can change the speed of motor by changing the value of delay } for (a = 0; a <= 60; a += 1) // goes to 0 degrees to 180 degrees { pos +=1; pos2 +=1; pos3 +=1; m1.write(pos); m2.write(pos2); m3.write(pos3); delay(10); // you can change the speed of motor by changing the value of delay } }