Precision Pendulum Assembly: Calibration - Revision history

Ist428984: /* Local gravity access */

2021-08-26T14:05:12Z

Local gravity access

Ist428984: /* Local gravity access */

2021-08-26T14:01:11Z

Local gravity access

Ist428984: /* Local gravity access */

2021-08-24T15:10:09Z

Local gravity access

Ist428984: /* Local gravity access */

2021-08-24T12:55:13Z

Local gravity access

Ist428984 at 12:53, 24 August 2021

2021-08-24T12:53:17Z

Ist428984 at 11:49, 24 August 2021

2021-08-24T11:49:48Z

Ist428984 at 16:54, 23 August 2021

2021-08-23T16:54:28Z

Ist428984 at 16:53, 23 August 2021

2021-08-23T16:53:27Z

Ist428984 at 16:52, 23 August 2021

2021-08-23T16:52:56Z

Ist12916: /* String measurement */

2021-04-15T07:46:42Z

String measurement

← Older revision		Revision as of 14:05, 26 August 2021
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	Local gravity in big cities normally is well known and documented by national geological entities which encompasses usually the most accurate value. Nevertheless a good comparison can be obtained with spatial harmonics even calculated on-line by a few calculators such as this [https://www.sensorsone.com/local-gravity-calculator/ Local Gravity Calculator].		Local gravity in big cities normally is well known and documented by national geological entities which encompasses usually the most accurate value. Nevertheless a good comparison can be obtained with spatial harmonics even calculated on-line by a few calculators such as this [https://www.sensorsone.com/local-gravity-calculator/ Local Gravity Calculator].
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 ===Local gravity access===
-Local gravity in big cities normally is well known and documented by national geological entities which encompasses usually the most accurate value. Nevertheless a good comparison can be obtained with spatial harmonics even calculated on-line by a few calculators such as this  [https://www.sensorsone.com/local-gravity-calculator/ Local Gravity Calculator]
+Local gravity in big cities normally is well known and documented by national geological entities which encompasses usually the most accurate value. Nevertheless a good comparison can be obtained with spatial harmonics even calculated on-line by a few calculators such as this  [https://www.sensorsone.com/local-gravity-calculator/ Local Gravity Calculator].
 {|

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 {|
-[[Precision Pendulum Assembly: Software management| Previous Page (Software manegement)]]
+[[Precision Pendulum Assembly: Software management| Previous Page (Software management)]]
 |}
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 Local gravity in big cities normally is well known and documented by national geological entities which encompasses usually the most accurate value. Nevertheless a good comparison can be obtained with spatial harmonics even calculated on-line by a few calculators such as this  [https://www.sensorsone.com/local-gravity-calculator/ Local Gravity Calculator]
 [[Precision Pendulum Assembly: Software management| Previous Page (Software manegement)]]
 [[Precision Pendulum Assembly: Partners| Next Page (Partners)]]
 ==Links==

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      • Data bits: 8
      • Stop bits: 1
-Please be aware if you have another application using the corresponding device. Actually you can have the JAVA deamon running, preventing access to the serial port. In such case it should be stopped (by running the command with the flag STOP) prior to run the minicom application as in the following example (please adapt to your local path):
+Please be aware if you have another application using the corresponding device. Actually you can have the JAVA daemon running, preventing access to the serial port. In such case it should be stopped (by running the command with the flag STOP) prior to run the minicom application as in the following example (please adapt to your local path):
   elab@WP-RAI:~ $ /home/wpa/rec-deployment/wpunicvrai/wpunicvraiDaemon.sh Stop
-After any maintenance where it was deemed necessary to stop this daemon is as to be restarted by issueing the reciprocal command:
+After any maintenance where it was deemed necessary to stop this daemon is has to be restarted by issueing the reciprocal command:
   elab@WP-RAI:~ $ /home/wpa/rec-deployment/wpunicvrai/wpunicvraiDaemon.sh Stop
@@ Line 80: / Line 80: @@
 * '''stp''': Stops an experiment and send the micro-controller to the STOPED state.
 * '''rst''': Resets the micro-controller and send it to the RESET state.
-* '''ids''': Ask the micro-controller to send an its identifications. E.g.: IDS     WP_LIS  STOPED
+* '''ids''': Ask the micro-controller to send its identifications. E.g.: IDS     WP_LIS  STOPED
 * '''cfg''': Send the configuration for a new experiment. This command accepts two integer parameters: 1st - initial displacement in cm, 2nd - number of oscillations
 :[[File:cfg_dsPic_return.png|x60px|cfg dsPic return]]
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 * '''stop ball''': This command is used to stop the ball from oscillating. After stopping the ball, the shovel resting position is at the photo-diode/photo-gate.
 * '''prepare launch''': This command accepts one integer which corresponds to the initial displacement (maximum amplitude) before releasing the ball. The command displaces the shovel to the required position and rests at that position.
-* '''launch ball''': This command released the ball by sending the shovel to the origin at its maximum speed.
+* '''launch ball''': This command releases the ball by sending the shovel to the origin at its maximum speed.
 * '''test laser''': This function is used to simultaneously test the laser and the photo-gate/photo-diode. A more detailed description of this command is found in [[#Laser and photo-gate test|Laser and photo-gate test]] as well as procedures to check in case of a failed test.
 * '''go to origin''': This command accepts two inputs: 1st - speed in cm/s (double) and 2nd - acceleration in cm/s² (double). It sends the shovel to the origin (until it reaches the micro-switch).
@@ Line 99: / Line 99: @@
 * '''reboot''': Performs a software reset to the micro-controller. Before resetting, the micro-controller stores the current number of oscillations into the flash memory.
-Commands to set the specific parameters for the experiment (see section [[#Setting specific parameters for the experiment|Setting specific parameters for the experiment]] for more details) and stores them in the flash memory so that they are not lost in case of a power down situation:
+Commands to set the specific parameters for the experiment (see section [[#Setting specific parameters for the experiment|Setting specific parameters for the experiment]] for more details). This parameters are stored in the flash memory so that they are not lost in case of a power down situation:
 * '''set maximum position''': Stores the shovel maximum absolute allowed position in cm (where it is mechanically impossible to go further in the forward direction).
 * '''set sphere diameter''': Stores the sphere diameter in cm and measured at the equatorial plane.
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 Current values/parameters for information:
 * '''expected period''': Shows the expected oscillation period in seconds. This value is calculated with the pendulum length and it essential for the proper operation of the experimental apparatus.
-* '''uptime''': Shows the time in secdons since the micro-controller was powered up.
+* '''uptime''': Shows the time in seconds since the micro-controller was powered up.
 * '''shovel is at origin''': Indicates if the shovel is located at the origin (yes/no).
 * '''shovel is at photodiode''': Indicates if the shovel is located at the photo-diode/photo-gate (yes/no).
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 The micro-controller has a dedicated function (accessible from the console menu) to test the laser and photo-gate simultaneously. This function consist of blinking the laser 5 times with a full period of 100 ms (500 ms total). If the photo-gate correctly detects the laser state the test will be successful. To manually run the laser and photo-gate test, just type the “test laser” command in the console.
 During booting, the micro-controller runs the laser and photo-gate test function to ensure that both components are working properly. If the test fails, the micro-controller returns the “ERR1” error code. This error can be associated with one or more of the following possible problems:
-* Wrong electrical connections: Check section [[#Connections|Connections]] to ensure that both laser and photo-gate are properly connected to the micro-controller.
+* Wrong electrical connections: Check section [http://www.elab.ist.utl.pt/wiki/index.php?title=Precision_Pendulum_Assembly:_Electrical_interfaces#Connections | Connections] to ensure that both laser and photo-gate are properly connected to the micro-controller.
 * Laser and photo-gate misalignment: Check if the laser light is properly pointed to the photo-gate structure hole and adjust as described in section [[#Photo-gate and laser alignment|Photo-gate and laser alignment]] if needed.
 * The photo-gate is always closed (conducting): If the ambient light is too intense or if some source of light other than the laser is going through the photo-gate structure hole with enough intensity, it can happen that the photo-gate is always conducting making it impossible to the micro-controller to distinguish between laser ON and OFF states. In this case, the solution is to reduce the ambient light or change the experiment orientation so that the photo-gate receives less light.
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-* '''photodiode position''': The potodiode position corresponds to the location of the shovel when this one is stopped at the photo-diode/photo-gate, see the figure below for illustration. The procedure to obtain this position is the following:
+* '''photodiode position''': The photodiode position corresponds to the location of the shovel when this one is stopped at the photo-diode/photo-gate, see the figure below for illustration. The procedure to obtain this position is the following:
 :* locate the shovel beyond (in the forward direction) the photo-gate and laser location. This can be achieved by using the command "move forward", as before.
 :* send the shovel to the photodiode using the command "move to photodiode", e.g., "move to photodiode 2 2" (to use a small speed of 2 cm/s)
@@ Line 197: / Line 197: @@
 ===Local gravity access===
-Local gravity in big cities normally is well known and documented by national geological entities which encompasses usually the most accurate value. Nevertheless a good comparison can be obtained with spatial harmonics even calculated  on-line by a few calculators such as this [https://www.sensorsone.com/local-gravity-calculator/ Local Gravity Calculator]
+Local gravity in big cities normally is well known and documented by national geological entities which encompasses usually the most accurate value. Nevertheless a good comparison can be obtained with spatial harmonics even calculated on-line by a few calculators such as this  [https://www.sensorsone.com/local-gravity-calculator/ Local Gravity Calculator]
 [[Precision Pendulum Assembly: Partners| Next Page (Partners)]]

@@ Line 203: / Line 203: @@
 ==Links==
-*[[Montagem do pêndulo de precisão: Calibração | Portuguese Version (Versão em português)]]
+*[[Montagem do Pêndulo de Precisão: Calibração | Portuguese Version (Versão em português)]]
 *[[Conjunto de péndulo de precisión: Calibración  | Spanish Version (Versión en español)]]

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 * '''temperature''': Indicates the temperature in degrees Celsius. The temperature sensor is located in the DB25 box connected to the micro-controller board.
 * '''ERR 1''': Indicates that there is a problem with the laser or photo-diode/photo-gate. See [[#Laser and photo-gate test|Laser and photo-gate test]] for more details and debug procedures.
-* '''ERR 2''': Indicates that there is a problem with the micro-switch. See [[http://www.elab.ist.utl.pt/wiki/index.php?title=Precision_Pendulum_Assembly:_Electrical_interfaces#Connections | Connections]] to double-check that the micro-switch is properly connected.
+* '''ERR 2''': Indicates that there is a problem with the micro-switch. See [http://www.elab.ist.utl.pt/wiki/index.php?title=Precision_Pendulum_Assembly:_Electrical_interfaces#Connections | Connections] to double-check that the micro-switch is properly connected.
 ====Laser and photo-gate test====

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 ===String measurement===
-[[File:CalibracaoFitaMetrica.jpg||thumb|Measuring tape rigorous calibration with a caliper aid.|right|border|240px]]
+[[File:CalibracaoFitaMetrica.jpg||thumb|Measuring tape rigorous calibration with a caliper aid to surpass any offset.|right|border|240px]]
 [[File:CableMeasurement.png||thumb|Detail of the pendulum cable length calibration, where the plateau touch the measuring tape to avoid parallax giving in this particular case 2824 mm.|right|border|240px]]
 The pendulum accuracy depends strongly in its rigorous length measurement (~2,8 m) with less than 0,5 mm. Indeed this is the crucial factor to achieve the desired 0,02% accuracy and for that propose a well-calibrated measuring tape as to be chose. If this method is adopted special care has to be taken to avoid parallax. Alternative methods like ultrasonic measurement with laser targeting are the best, using a metallic or marble stone plane fitted tangential to the weight (allowing it to roll but touching the plane). With this method a few takes shall be done surrounding the ball and their average value will be considered the pendulum reference length.