Design and implementation of an RF vehicle speed governor system in Zimbabwe.

This thesis has been submitted in partial fulfillment of the Master of Science degree in Communication Engineering at the University of Zimbabwe. Marisa of the University of Zimbabwe for his in-depth support and contributions at every stage of this research. The proposed dissertation is an attempt to address the problems of high road fatalities due to excessive speed.

Today, speeding has become one of the leading causes of most accidents in Zimbabwe. In general, speeding is the result of restlessness, bad behavior and negligence on the part of the driver. With the number of accidents increasing, it has become necessary to develop and implement a system that can automatically detect and monitor speeding violations in vehicles.

As an addition to other systems already in place, this research makes use of the RF technology to detect and control speed when the vehicle in question exceeds the proposed speed limit on any or in the most dangerous part of the roads.

BACKGROUND
PROBLEM STATEMENT
AIM
OBJECTIVES
SCOPE OF THE STUDY
Hardware Requirements
Software Specifications
Thesis Outline

According to the WHO, the biggest risk factors for road accidents are speeding and failure to comply with traffic regulations. One of the common and at the top of the list of all mistakes is over speeding. There are no speed cameras and appropriate monitoring system for identifying speeding vehicles in Zimbabwe.

Speed limits through signs have been in place since time immemorial, but have been found to be less effective as most of the motorists do not obey them, resulting in serious accidents. The Vehicle Speed Governor Project is a great solution to this problem as it provides speed limits through a programmed control mechanism. To design a vehicle speed controller over an RF communication system to reduce road accidents due to excessive speed.

This research is limited to the design of an electronic vehicle speed control system that limits the vehicle speed to a specified speed.

Fig 1.10: Graph showing averages of accidents recordings between 2014 and 2018 in Zimbabwe.[11]

Background

Thus, the ECU is a crucial factor in controlling fuel consumption, which in turn has a direct impact on engine power and speed. Fuel delivery and control are key, as they determine the power and speed of the engine [23]. However, it is the responsibility of the ECU to restrict the airflow and fuel supply to the engine to ensure that the vehicle does not exceed a predefined top speed on that section of road.

If it chooses to do so, the fuel to the engine is reduced, reducing the speed of the vehicle. The goal of a communication system is to deliver a specific message to the destination over a noisy physical channel. The digital modulator then receives the output from the channel encoder, which will then be mapped onto signal waveforms. The output of the demodulator is a sequence of numbers which is then moved to the channel decoder.

The main purpose of digital signal processing is to process these sampled signals. Rounding the values approximately equal to the analog values is the result of the digitization process [6]. We [6] denote the quantization operation on the samples 𝑥(𝑛) as 𝑄[𝑥(𝑛)] and let 𝑥𝑞(𝑛) denote the series of quantized samples at the output of the quantizer.

Fig. 2.1: Block diagram of an engine fuel injector system [34]

Introduction

It will then convert the signals into digital signals using the microcontroller's built-in ADC (analog-to-digital converter). The digital data generated by the variations of the potentiometer (on the transmitter) is transmitted via the transmitter's RF antenna, which is connected to the receiver on digital pin D2 of the microcontroller. The third goes from analog input 2 (𝐴2) to the middle pin of the potentiometer and provides a variable resistor.

This shaft, connected to the center pin of the potentiometer, can turn on either side of the wiper. In this design, however, the data module was connected to digital pin 2 of the Arduino Uno and the Vcc across was 5V. The average voltage is proportional to the width of the pulses, known as the duty cycle.

The higher the duty cycle, the greater the average voltage applied to the DC motor (high speed), and the lower the duty cycle, the smaller the average voltage applied to the DC motor (low speed). The supply signal consists of a train of voltage pulses such that the width of individual pulses controls the effective voltage level to the DC motor at the receiver in this design. The speed variations of the motor are perceived depending on the width of the pulses in the PWM output. The function used to output a PWM signal is analogWrite(pin, value) where pin is the pin number used for PWM output and value is a number proportional to the duty cycle of the signal.

The average voltage is proportional to the width of the pulses known as Duty Cycle as explained above. One of its pins is connected to the ground and the other to the 5 volt pin of the microcontroller. The middle pin, which controls the voltage variations, is connected directly to the LCD's Vee pin.

The second potentiometer, connected to analog pin A2 on the microcontroller, is used to vary the speed of the motor locally and it is this speed that this design tries to control. The dc moto driver enable pin connected to 5V digital pin 8 of the microcontroller is also defined. In the setup() function, the statement lcd.begin(20,4) defines the size of the LCD used for the display.

AnalogWrite(pmw1, dcSpeed), then writes the analog value (PWM wave or duty cycle) to a pin 9 of the microcontroller as defined by the integer variable pwm1 which is then used to drive the motor clockwise.

Overview
Results for Transmitter Design
Results for Receiver Design
Circuit Simulation

Fig. 4.2 shows a linear relationship between input voltage and output signal level variations on the transmitter side. Each of the control digital output values corresponds to a required speed value in km/h which is then sent to the receiver as defined in the code in section 3.3 of chapter 3. From this code and also from table 4.1 above shows that the digital output range between 0 and 100, corresponds to and sends the speed signal of 40 km/h, between 101 and 300 sends the speed signal of 80 km/h, between 301 and 600 corresponds to and sends the speed signal of 100 km/h and that finally between 601 and 1023 corresponds to and sends the speed signal value of 120 km/h to the receiver.

In the design, the receiver generates several uncontrolled velocity values, which must then be weighted and controlled by the velocity signal received from the transmitter. So, for taking the readings of the uncontrolled receiver, the transmitter is first turned off. By switching on the transmitter and receiver, and varying the signal speed at both ends, the speed of the receiver was controlled accordingly.

The left side of Table 4.2 above shows the speed readings as read at the receiver before the speed signals are transmitted from the transmitter. The right side of table 4.2 above shows the regulated speed of the dc motor after transmitting the speed signals from the transmitter. For a voltage of 1.25 V at the transmitter, the dc speed at the receiver decreased from 100 km/h to 80 km/h.

At a voltage of 2.50 V at the transmitter, the one-way speed at the receiver decreased from 120 km/h to 100 km/h. At 3.75 V at the transmitter, the one-way speed at the receiver decreased from 140 km/h to 120 km/h. At 5 V at the transmitter, the one-way speed at the receiver decreased from 160 km/h to 120 km/h.

Where 𝑉𝑒𝑓𝑓 is the applied input voltage from the transmitter and varies between 0 and 5 volts and 𝑉𝑠 is 5 V. Using the prototype transmitter developed in this design, pulse width modulated signals generated at the receiver at various vehicle speeds were captured by digital oscilloscope and the results are as shown in fig.

Table 4.1: Transmitter Readings Input Voltage (volts) Digital Signal

CONCLUSION

RECOMMENDATION

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