Geschwindigkeitsmessstrecke mit Arduino

Abb. 1: Geschwindigkeitsmessstrecke

Author: Syed Rafsan Ishtiaque
Art: Praxissemester
Dauer: 02.05.2023 - 21.08.2023
Betreuer: Prof. Dr.-Ing Ulrich Schneider

Einleitung

Developing the speed measuring unit for any car project

Anforderungen

Tabelle 1: Funktionale Anforderungen an die Geschwindigkeitsmessstrecke

ID	Inhalt	Ersteller	Datum	Geprüft von	Datum
1	Die Geschwindigkeit eines vorbeifahrenden RC-Fahrzeugs muss in m/s auf 3 Nachkommastellen genau gemessen werden.	Ulrich Schneider	30.06.2023
2	Die Geschwindigkeitsmessstrecke muss im Akkubetrieb laufen.	Ulrich Schneider	30.06.2023
3	Die Geschwindigkeitsmessstrecke muss über einen Schalter ein- und ausgeschaltet werden können.	Ulrich Schneider	30.06.2023
4	Die Geschwindigkeitsmessstrecke muss auf einem Display auf 2 Nachkommastellen in m/s angezeigt werden.	Ulrich Schneider	30.06.2023
5	Der Aufbau muss robust und professionell sein und mind. 10 Jahre betrieben werden können. Alle Verbindungen müssen hierzu zugentlastet sein.	Ulrich Schneider	30.06.2023
6	Die Arduino IDE muss für die Programmierung verwendet werden. Die Programmierrrichtlinien sind einzuhalten und der Quelltext ist nachhaltig zu kommentieren.	Ulrich Schneider	30.06.2023
7	Der Quelltext ist in SVN zu sichern und in diesem Artikel zu verlinken.	Ulrich Schneider	30.06.2023

Komponententest

Beispiel

Tabelle 4: Testbericht für den Komponententest von Kartenfunktion.m

ID	Testfallbeschreibung	Eingänge x,y,PosAlt,Ausrichtung,Karte,Bumper,Ultraschall,Perimeterschleife	Erwartetes Ergebnis	Testergebnis	Testperson	Datum
1	Der Mäher fährt kein Feld weiter.	0.1, 0.0, [0;0], 0, Karte, 0, 0, 1000	Kein neues Feld wird blau markiert.	OK	Prof. Schneider	21.01.2018

Link zum Quelltext in SVN

Table 1: Functional Requirement

ID	Topic	Result	Date	Comment (if any)
1	Sensors measuring data	Both of the sensors functional	30.06.2023	The range of measurement is optimum, 30 cm
2	LCD display showing results	The measured data can be seen	30.06.2023	The display has a good color contrast
3	External power source
4	Base & structure of the Unit	The measuring unit has a solid base and stable structure	30.06.2023	The lose parts of the previous version were fixed

Table 2: Non-Functional Requirement

ID	Topic	Result	Date	Comment (if any)
1	Sensors have protector shade on top	The measured data is consistent	30.06.2023	Direct interference of light can alter sensor data
2	LCD user interface	LCD shows a staring announcement and other necessary ones	30.06.2023	The interface is user friendly
3	Controlling of the power source
4	Cable stress relief for LCD
5	Cable and wire holder for the Unit	A protective tray on the bottom for holding cables	30.06.2023	To avoid wire/ cable entanglement, it was necessary
6	External Arduino shield for future development	A shield is attached on the arduino	30.06.2023	Useful for any development or if needs to repair

Hardware

Sensor

Sharp 2D120X F 09

The Sharp distance measuring sensor is used to determine the speed/ velocity of the car unit. In this case, two identical sensors were used. According to the manufacturer SHARP , the range of the sensor is 4 cm to 30 cm, typical response time apprx. 39 ms, typical start up delay apprx. 44 ms, Average Current Consumption: 33 mA. The operating temperature is -10°C to 60°C, so that is ideal for this project as it is initially an indoor project. according to the stamp on the sensor, the manufacturing date was September 2016. According to the data sheet, the sensor should be mounted on any frame in such way that it gives the optimum result. For that the general instructions are available on the Data Sheet .

Display

LED Based 8 segment display

A simple LED based 8 segment display was the initial plan for the project. For reference, the LED tutorial guide for Micro-controller was used. But it had limitation. So we decided to upgrade the display with C547B transistor . An initial model is developed with C547B transistor.

[Update]
1. The circuit for LED display worked. It was tested for one segment, consisting two LED. The supply voltage was 5V, base resistor 1K ohm, collector resistor 470 Ohm.
2. We finalized the complete circuit setup for the LED display. But we will now implement a LCD display. The reason for doing that, a digital LCD display will enable us to showcase more data related to the speed tracking sensor. Also the data can be transferable and possible to store it for future reference.

LCD Display Blue with I²C

The LCD display we will use is QAPASS LCD I²C. This is a variant of the normal LCD display. It is combined with an I²C module . This will enable us to add further feature to the system. The next development of I²C is I³C. Both I²C and I³C were designed as "Controller" and "Target" bus system (previous master & slave bus concept). The two signal lines for I²C are SCL: Serial Clock and SDA: Serial Data line. But we have to consider the distance of the data transmission while using the I²C. The LCD display is functional. It is receiving messages and displaying them. Next step will be optimizing the sensor data and making a robust system.

Future development

Instead of using a led based display we can implement MQTT protocol to get the end result from the sensor in our smartphone with help of raspberry pi. That will allow to record the result more conveniently. During the implementation of MQTT protocol, the raspberry pi module will work as MQTT broker and both Arduino and Smartphone will be MQTT client. The broker will receive sensory data from the Arduino (1st client) and then it will forward the message to the smartphone (2nd client). As the system will only be used to receive the data collected by the sensor and processed by the arduino and not to control the sensor, it will be uni-directional; that means we will opt out the part to control any sensor from the smartphone application.

LCD Display Holder

To mount the LCD on the main structure, we have designed a holder in Solidworks and printed it in 3D printer. The holder model can be updated based on requirements.

Source Code

The arduino code for the sensor and LCD displays are developed and implemented. We used median filters to cancel out/ limit the noise. We will made two separated arrays for the median filter. For each array there will be separate index pointers. So the two sensors data will be filtered out separately, in that way one's noise will not affect the other.
[Update] We are modifying the code so that the speed tracker can measure the speed from both direction

Test Run

We tested our measurement setup the remote controlled car and it worked good for uni-directional way. For bi-Directional, we still are in development phase.

Literature

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