AP_RangeFinder: TeraRangerI2C redefining the output distance logic with OutOfRange cases

libraries/AP_RangeFinder/AP_RangeFinder_TeraRangerI2C.cpp

@@ -28,6 +28,8 @@ extern const AP_HAL::HAL& hal;
 #define TR_WHOAMI  0x01
 #define TR_WHOAMI_VALUE 0xA1
 
+#define TR_OUT_OF_RANGE_ADD_CM 100 //cm
+
 AP_RangeFinder_TeraRangerI2C::AP_RangeFinder_TeraRangerI2C(RangeFinder::RangeFinder_State &_state,
                                                            AP_RangeFinder_Params &_params,
                                                            AP_HAL::OwnPtr<AP_HAL::I2CDevice> i2c_dev)
@@ -138,14 +140,15 @@ bool AP_RangeFinder_TeraRangerI2C::process_raw_measure(uint16_t raw_distance, ui
         return false;
     } else if (raw_distance == 0x0000) {
         // Too close
-      return false;
+        output_distance_cm = 0;
     } else if (raw_distance == 0x0001) {
         // Unable to measure
-      return false;
+        // This can also include the sensor pointing to the horizon when used as a proximity sensor
+        output_distance_cm = max_distance_cm() + TR_OUT_OF_RANGE_ADD_CM;
     } else {
         output_distance_cm = raw_distance/10; // Conversion to centimeters
-    return true;
     }
+    return true;
 }
 
 /*