Development of an Android-Based, Voice-Controlled Autonomous Robotic Vehicle ^†

Abstract

This research presents the development of an android-based, voice-controlled autonomous robotic vehicle. This article was developed in a way that the robotic vehicle was controlled using voice commands. An android application combined with an android microcontroller was used to achieve this task. The connection between the android app and the autonomous vehicle was facilitated using Bluetooth technology. The vehicle was controlled with either the aid of the buttons on the app, or by spoken commands from the user. The movement of the vehicle was achieved by using four DC motors connected with the microcontroller at the receiver side. The commands from the app were converted into digital signals using the Bluetooth RF transmitter within a specific range (of around 100 m) of the autonomous vehicle. At the receiver end, the data gets decoded by the receiver and is fed to the microcontroller which moves the DC motors of the vehicle for navigation. The voice-controlled autonomous robotic vehicle performed navigational tasks by listening to the commands of the user. This was achieved by converting voice commands into text strings which are readable by the Arduino microcontroller on the android app in order to control the navigation of the robot. The vehicle was tested under different conditions and was observed to perform better using this technique and also the results were satisfactory when compared with other previous research that has been conducted in this area.

1. Introduction

Robotics is growing fast and becoming one of the most researchable areas in engineering, even though robotics emanated from advancement of technology. This is contrary to human perception, as they are usually amazed by the concept of artificial intelligence [1,2]. The reason for using robots is that they provide cheap labor, and because of their high accuracy of output. They have different applications which all possess the problem of finding a technique to accurately and efficiently control robots [3] that can be applied in medicinal, industrial, transportation, military and surveillance contexts [4,5]. The framework of the autonomous voice-controlled vehicle consists of the chassis, the Bluetooth module, DC motors, Arduino Uno microcontroller and other important components. The control of a vehicle is realized using a Bluetooth communication module [3]. This is connected to the DC motors and the microcontroller. The vehicle is operated by giving wireless commands from the app using the functions that were initially programmed for it. The vehicle moves in four directions: right, left, forwards or backwards. In the case of the right direction, the four motors move in the clockwise direction, while for the left direction, the motors move in the anticlockwise direction. For forward movement, the motors move in the forward direction, while for backwards movement, they move in reverse directions. Also, in order to stop the movement of autonomous vehicles, the motion of the motors is stopped, and the vehicle stops moving [6]. However, the autonomous vehicle receives command through the android app using Bluetooth medium to control the movement of the motors.

There are some research works in the field of voice-controlled autonomous robotic vehicles. Ref. [7] developed and designed a voice-controlled talking robot using a mobile phone based on an Arduino Uno microcontroller. The robot’s movement was based on the voice commands that were given to it, and, in turn, responded to the command that was given. A memory card was provided in the design for the robot to save prerecorded audio files that were used for developing the talking system of the robot. Also, ref. [8] developed a robotic vehicle which was controlled by voice commands through a smart phone using an Arduino Uno microcontroller and a Bluetooth sensor. The VoiceBot application and Google Voice were used as voice commands. A low-cost autonomous robotic vehicle was presented by [9] which was controlled by voice command. The user of the robotic vehicle may be located at a particular location and as long as the user is connected to the internet, the vehicle follows the voice instructions. The concept was successful using Arduino IDE, Adafruit, NodeMCU ESP866 and Google Assistant and If-This-Then-That (IFTTT). A voice-controlled robotic car was also produced by [10], the robotic car working principle was based on the Arduino Uno microcontroller, Bluetooth and motor drivers. The hardware component of the car was developed, while the software component was simulated, and later the two were interfaced in order to achieve effective coordination and control of the vehicle. In [11], a voice-controlled robot (VCR) which was mainly designed using Arduino IDE. The user provides voice commands to the vehicle using Google thing speech through an ESP32 microcontroller which forwards the commands to the Arduino on the robotic vehicle. The VCR was able to move in either the forward, backward, left and right directions. The robotic vehicle was designed using some predefined voice commands by [12]. The commands could be either forward, backward, left or right. A camera with an LCD screen was mounted on the vehicle to view distances of obstacles between the vehicles. Also, a GPS was attached to the vehicle to locate the position of the vehicle at any time. Finally, ref. [13] designed a robotic vehicle which uses voice commands using an android application for the navigation of the vehicle. The commands spoken were translated to text using speech-to-text in the android app before they were sent to the vehicle. The android app controls the vehicle using Bluetooth medium, which was embedded in the Arduino Uni microcontroller on the vehicle.

The rest of the paper is structured as follows: Section 1 discusses the introduction; Section 2 presents the materials used for the successful achievement of this article; Section 3 provides the results and discussion; and finally the conclusion is given in Section 4.

2. Materials

This subsection outlines the materials used for the design of the android-based voice-controlled robotic vehicle.

2.1. Arduino Uno Microcontroller

This is a programmable circuit board that is used in building electronic projects. It is an open-source platform which consist of software or an integrated development environment (IDE) that runs on a computer system. The codes are written in the IDE language and uploaded to the physical circuit board. The board contains a microcontroller which is programmed for controlling and sensing of objects in the physical world. Figure 1 shows the Arduino Uno microcontroller.

2.2. Direct Current (DC) Motor

This is a rotary electrical machine which converts direct current electrical energy into mechanical energy. Most DC motors rely on the forces produced by magnetic fields. They possess some internal mechanisms which is either electronics or mechanical to periodically change the direction of the current flow of the motor. DC motors can be controlled over a wide range either by using a variable voltage supply or by changing the field winding current strength. The DC motor is shown in Figure 2.

2.3. Four-Wheel Robot Chassis

This is a vehicle framework used for the control of the autonomous robot. The DIY four-wheel-drive robot chassis is the mechanical platform that is used for this robot. The kits include all the hardware and mechanical components which are required to mount the motors, wheels, bolts and nuts. Figure 3 shows the four-wheel robot chassis.

2.4. Battery

This is a collection of one or more cells whose chemical reactions create a flow of electrons in a circuit. Batteries are made up of three basic components: the anode, the cathode and an electrolyte [16]. Figure 4 shows a typical battery.

3. Results and Discussion

This subsection discusses the results that was obtained when the voice-controlled autonomous vehicle was coupled and tested. Firstly, the hardware interface, which is shown in Figure 5, was designed as the complete setup.

The software component was simulated and embedded into the setup using the sequence shown in Figure 6.

In Figure 6, how the movement of the autonomous robot was achieved using voice control is shown whereby the command was given to the robot using a Bluetooth medium with the aid of an android application developed for the robot movement. Figure 7 shows the android app for the robot.

In Figure 7, it is shown that the movement of the robot could be forward, backward, right and left. The robot had the capability of either going in the forward direction, backward direction, left direction and right direction. These all depended on the user’s discretion.

Also, the vehicle was subjected to a voice command test, Bluetooth range test, maximum weight lift test and maximum lift angle test. It was observed that for the voice command test, the vehicle responded to all the commands accordingly. Also, for the Bluetooth test, it was observed that the maximum range obtained was 8.5–12 m depending on the location. For the maximum weight lift test, different weights were attached to the motor arm and lifted automatically and the maximum mass of the lifted objects was 50 g. For the maximum lift angle test, it was observed that the maximum lift angle the robotic vehicle could raise was 1.9 cm, this is due to the jack rod length constraint. The summary of the test carried out on the vehicle is shown in

Table 1. Summary of the command actions obtained from the vehicle.

	Vehicle		Appendage
Command	Right Motor	Left Motor	Arm Motor	Gripper Motor
	Action	Action	Action	Action
“Backward”	Rotate Anticlockwise	Rotate Anticlockwise	Off	Off
“Forward”	Rotate Clockwise	Rotate Clockwise	Off	Off
“Right”	Off	Rotate Clockwise	Off	Off
“Left”	Rotate Anticlockwise	Off	Off	Off
“Down”	Off	Off	Rotate Anticlockwise	Off
“Up”	Off	Off	Rotate Clockwise	Off
“Close”	Off	Off	Off	Rotate Anticlockwise
“Open”	Off	Off	Off	Rotate Clockwise
“Stop”	Off	Off	Off	Off

.

In Table 1, it is shown that the autonomous robotic vehicle performed satisfactorily when controlled with the android app, and also when executing the commands that was set for it to execute experimentally.

4. Conclusions

An autonomous android-based, voice-controlled robotic vehicle was developed in this article. Autonomous robots have become an integral aspect of human life, as, since the advent of these devices, they have made things easier. The robotic vehicle was controlled using an android app through the medium of Bluetooth. An Arduino Uno microcontroller was used to achieve this mission. The interface on the android app used button or spoken word commands. Theses buttons were forward, backward, left and right buttons. The movements of the vehicle were achieved using four DC motors based on the command given by the user. These commands on the android were converted into digital signals using a Bluetooth RF transmitter, where, at the receiver end, the data was decoded and fed to the Arduino microcontroller to move the DC motors for navigation of the vehicle. Testing was conducted on the vehicle using a Bluetooth range test, maximum weight lift and maximum weight angle test. They showed that the robotic vehicle performed satisfactorily. This could be made and applied to real-world applications. Further research should consider how to incorporate artificial intelligence into the robotic vehicle.