Prof. J. Walter - Informationstechnik, Mikrocomputertechnik, Digitale Medien Concept Development
Hochschule Karlsruhe Logo Bachelor Thesis
Public IoT: Smart Street Light for Moving Object
Winter Semester 2018/2019
Nabilah Binti Salehuddin (65634)

3.9 Concept Development

From the existing project research, most of the project only use model for simulation without applying in real life. Therefore, for this project my goal is to make a real life application based on these existing system and project. As for the product available in the market which is used in real world, they use high technology with very secure protection in terms of database resulting a very high cost. Hence for this project, I want to create a simpler smart street light system based on moving object with lower cost. The system can be used around campus of Hochschule Karlsruhe in order to manage the lamp around the campus area.

Basic concept

The basic concept of this project is when there is very little light intensity or no light at all, LDR will allow current pass through it and PIR sensor can sense any motion in its detection range. If there is a motion detected, ESP32 as microcontroller that receive the input signal from sensor will stimulate the relay to switch on the lamp. The lamp will switch on until the object/subject move away from the lamp. The system and status of the lamp can be monitored and accessed everywhere from the browser that will be connected via WiFi. Apart from automated system, there will be an option to operated this system manually via server.

Concept development:

1) Separated and multiple power supply

As LED lamp used is AC appliance, it is necessary to supply it with AC power supply direct from the home socket. For small component like ESP32 and sensor, since they operated in DC I want to provide it with rechargable DC power supply which is for example using power bank. For the model of the system, I used the basic electrical connection as shown below. Additional component can be added later into the circuit such as relay or MOSFET driver.

2) Web browser for controlling and monitoring via WiFi using WebSocket

The connection between client and server can be visually displayed on the web browser. The program should run according to the flowchart shown below.

Figure 3.9.3: Flowchart of system
In the browser user can check the status of each lamp available whether it is on or off. First, user will have to enter the IP address of their device (in this case the IP address of ESP32) in order to establish communication between client and server. From the server, user can obtain data such as light intensity, presence of motion and also the lamp status. In case there is any failure detected, the lamp can also be operated manually by man via manual mode option as emergency measurement.

Figure 3.9.4: Sketch design of user interface

Web Page
3) Mechanical model for simulation

As a development from existing project, I want to turn this street lamp system into real life application.
In order to build a real life mechanical model, I need to have:
- a road/passage where the lamp poles will be installed,
- LED lamp
- stand alone lamp poles that is reduced in size compared to standard lamp stand with adjustable height: to adjust the height of the lamp   pole according to size of moving objects,
- LDR and PIR sensor attach on each lamp stand,
- suitable objects as references for moving objects (Fischertechnik cars and actual persons).

Figure 3.9.5: Plan of mechanical design

Breadboard Model
In addition, I also will be using a breadboard model in order to simulate the whole system. By using this model, I can test the system before realizing into real life application. This is important to detect any possible problem that could occur, as safety measure, and also to make sure the program run accordingly.

Figure 3.9.6: Model using breadboard

Using the above concept, there are multiple alternatives that can be considered as a solution.
Description for Alternative Solutions
1) Alternative 1
In this concept, each lamp will has sensors attached on it but only will be controlled by a single microcontroller and a MOSFET driver. This means, all the output actuators will be supplied with voltage and current from the ESP32 itself while the lamps will be powered on by the MOSFET driver which get the voltage from DC supply.

Figure 3.9.7: Block diagram for electrical connection (Alternative 1)
2) Alternative 2
Act as a stand alone system where each pole has their own microcontroller that will be connected to the router. The microcontroller will act as a station to get internet from the router.  Each lamp is controlled by a single MOSFET driver and also has their own DC power supply.

Figure 3.9.8: Block diagram for electrical connection (Alternative 2)
3) Alternative 3
Similar to Alternative 2 but the difference is only a single MOSFET driver will be used to controll all lamp in which the lamp get their power supply from same DC supply.

Figure 3.9.9: Block diagram for electrical connection (Alternative 3)

Based on all these alternatives, there are several conditions being considered upon selecting suitable solution:
1) Enough voltage supply and current
2) Easy to be monitored
3) Flexible system design
4) Costly effective
5) Able to be realized into real application
6) Safe and reliable (long-lasting)

Circuit Testing

1) Basic circuit setup consist of ESP32, an LED and also LDR.

Figure 3.9.10: Basic circuit setup for testing

Basic circuit testing using 1 LED

2) Circuit buildup with addition of  MOSFET driver to contol 1 LED and 4 LEDs at the same time.

Figure 3.9.11: Circuit setup with addition of MOSFET driver

Switching on 1 LED using MOSFET driver

  With Support of Prof. J. Walter Winter Semester 2018/2019