bugfix in calibration procedure

raspberry-pi/sensors/acusticSensor.py

@@ -111,27 +111,28 @@ class AcusticSensor:
         self.log_handler.log_and_print("calibration measurements:", self.cal_values)
         
         # calculate distances from config
-        #          /|                               _.-|
-        #      d1 / |                       d2  _.-`   |
-        #        /  | y_off + calYoff       _.-`       | y_off + calibration_y_offset
-        #       /___|                     -____________|
-        #       x_off                     x_off + width
+        #                                     /|\                              
+        #    d1    d2                     d3 / | \ d4                     
+        #   _..'|'.._y_off + calYoff_2      /  |  \y_off + calYoff_2     
+        #  /____|____\                     /___|___\                 
+        # x_off                            x_off                     
         distance_1 = math.sqrt((self.calibration_x_offset + self.left_sensor_x_offset)**2 + (self.sensor_y_offset + self.calibration_y_offset_1)**2 )
         distance_2 = math.sqrt((self.calibration_x_offset + self.left_sensor_x_offset)**2 + (self.sensor_y_offset + self.calibration_y_offset_2)**2 )
         distancedif = distance_2 - distance_1
-        timedif = self.cal_values["front"][0] - self.cal_values["back"][0]
+        timedif = self.cal_values["back"][0] - self.cal_values["front"][0]
         # speed of sound in mm/us
         sonicspeed_1 = distancedif / timedif
-        # processing time overhead in us
-        overhead_1 = statistics.mean((self.cal_values["front"][0] - distance_1/sonicspeed_1, self.cal_values["back"][0] - distance_2/sonicspeed_1))
 
         # same for the second set of values
-        distance_1 = math.sqrt((self.right_sensor_x_offset + (self.field_width - self.calibration_x_offset))**2 + (self.sensor_y_offset + self.calibration_y_offset_1)**2 )
-        distance_2 = math.sqrt((self.right_sensor_x_offset + (self.field_width - self.calibration_x_offset))**2 + (self.sensor_y_offset + self.calibration_y_offset_2)**2 )
-        distancedif = distance_2 - distance_1
-        timedif = self.cal_values["back"][1] - self.cal_values["front"][0]
+        distance_3 = math.sqrt((self.right_sensor_x_offset + (self.field_width - self.calibration_x_offset))**2 + (self.sensor_y_offset + self.calibration_y_offset_1)**2 )
+        distance_4 = math.sqrt((self.right_sensor_x_offset + (self.field_width - self.calibration_x_offset))**2 + (self.sensor_y_offset + self.calibration_y_offset_2)**2 )
+        distancedif = distance_4 - distance_3
+        timedif = self.cal_values["back"][1] - self.cal_values["front"][1]
         sonicspeed_2 = distancedif / timedif
-        overhead_2 = statistics.mean((self.cal_values["front"][1] - distance_1/sonicspeed_2, self.cal_values["back"][1] - distance_2/sonicspeed_2))
+
+        # processing time overhead in us
+        overhead_1 = statistics.mean((self.cal_values["front"][0] - distance_1/sonicspeed_1, self.cal_values["back"][0] - distance_2/sonicspeed_1))
+        overhead_2 = statistics.mean((self.cal_values["front"][1] - distance_3/sonicspeed_2, self.cal_values["back"][1] - distance_4/sonicspeed_2))
 
         # calculate calibration results
         self.sonic_speed = statistics.mean((sonicspeed_1,sonicspeed_2))