     //좌회전
     if( ch == 'a' )
     {
-      rc_pwm_L = constrain(rc_pwm_L--, 100, 2000);      
-      rc_pwm_R = constrain(rc_pwm_R++, 100, 2000);
+      rc_pwm_L = constrain(rc_pwm_L--, 0, 2000);      
+      rc_pwm_R = constrain(rc_pwm_R++, 0, 2000);
       RovServo[0].write(rc_pwm_L);    //좌측모터 출력 감소
       RovServo[2].write(rc_pwm_R);    //우측모터 출력 증가
       Serial.println("Left=");

    //상단모터 감속
    if( ch == 'e' )
    {
      rc_pwm_T = constrain(rc_pwm_T--, 100, 2000);
      RovServo[1].write(rc_pwm_T);   
      Serial.println("Top=");
      Serial.println(rc_pwm_T);

    //우회전
    if( ch == 'd' )
    {
      rc_pwm_L = constrain(rc_pwm_L++, 0, 2000);
      rc_pwm_R = constrain(rc_pwm_R--, 0, 2000);
      RovServo[0].write(rc_pwm_L);   // 좌측모터 출력 증가
      RovServo[2].write(rc_pwm_R);    //우측모터 출력 감소
      Serial.println("Left=");
