NewPing Library: HC-SR04, SRF05, SRF06, DYP-ME007, Parallax PING))) - v1.7

Using Arduino Sensors
373

for zero this will work, in that program

if ((da =0) && (db =0))
{
digitalWrite(lp,  HIGH);
digitalWrite(ln, LOW);
digitalWrite(rn, LOW);
digitalWrite(rp, HIGH);
Serial.println("go stright");
Serial.println(da);
Serial.println(db);
  
}