AlphaBot: Lane tracking with camera

Abb. 1: AlphaBot: Lane tracking with camera

Autor:	Syed Muhammad Abis Rizvi
Art:	Praxissemester
Studiengang:	ELE
Starttermin:	02.03.2026
Abgabetermin:	21.06.2026
Betreuer:	Prof. Dr.-Ing. Schneider
Sprache:	DE EN

Introduction

This is an Alphabot by waveshare which supports advanced navigation and sensing features. In this project our task is to drive the Alpha bot with in the right lane along the course by using a pixy2 camera and modify its speed limit. We also added a GY-85 gyroscope IMU sensor to record the Yaw rate so that we can later calculate the yaw angle from the yaw rate data, later we plan to add a Bluetooth module to get the data wirelessly.These components works together so that Alpha bot can drive independently in real time.

Requirements

Table 1: Requirements for the Unit

Req.	Description	Priority
1	An AMR must drive autonomously in the right-hand lane.	1
2	The Topcon Robotic Total Station is used as the reference measurement system.	1
3	The AMR must evaluate the road data via camera (Pixy 2.1) to follow the lane.	2
4	The reference values ​​must be recorded with MATLAB (x, y, ${\mathrm{\Psi }}_T$).	1
5	Measurement errors must be appropriately filtered.	1
6	The two-dimensional digital map showing the robot's pose during movement must be provided as a MATLAB® file (.mat).	1
7	The solution path and solution must be documented in this wiki article.	1
8	An AlphaBot must be used as the AMR.	1
9	MATLAB®/Simulink must be used as the control software.	1
10	From the measured yaw rate ${\dot{\mathrm{\Psi }}}_G$ the yaw angle ${\mathrm{\Psi }}_G$ must be determined and compared to the reference ${\mathrm{\Psi }}_T$ from Req. 4.	1
11	The AlphaBot's speed must be optimized to it's maximum.	1

Working principle

The AlphaBot uses the Pixy" camera to detect the lane which helps Alphabot to poistion itself on the track and based on this infromation the motor runs and the Alphabot runs independently on the track and stop immediately when it does not detect any line.

GY-85 IMU sensor measures the yaw rate, which is used to detemine the AlphaBot's (yaw angle) according to its movements.

All componennts work together in real time to make sure the AlphaBot runs independently in real time.

Technical Overview

The system is built on the waveshare AphaBot which is integrated with motors. A pixy2 camera is used for keeping the AlphaBot on track.

Gy-85 IMU used to record yaw rate and yaw angle.

Bluetooth module is used for collecting the output wirelessly in real time.

Pin Assignment

Component	Module Pin	Connected Controller Pin
Pixy2 Camera (I2C)	SDA	A4
	SCL	A5
	VCC	5V
	GND	GND
GY-85 IMU Sensor (I2C)	SDA	A4 (shared I2C)
	SCL	A5 (shared I2C)
	VCC	3.3V / 5V
	GND	GND
Bluetooth / Serial	TX	RX (D0)
	RX	TX (D1)
	VCC	5V / 3.3V
	GND	GND
Left Motor	PWMA	D6 (PWM)
	AIN1	A1
	AIN2	A0
Right Motor	PWMB	D5 (PWM)
	BIN1	A2
	BIN2	A3
Power Supply	Battery / VCC	AlphaBot power input; sensors powered via onboard voltage regulator

Measurement method

Measurement is done by using onboard sensors on AlphaBot. Pixy2 camera detects the lane position from which lateral error is calculated. The GY-85 IMU sensor measures the yaw rate which helps determine the yaw angle.

Formula for yaw angle.

\[ \theta(t) = \theta_0 + \int_{0}^{t} \omega(t)\, dt \]

\[ \theta_k = \theta_{k-1} + \omega_k \cdot \Delta t \]

Measuring Circuit

The measuring circuit consists of the AlphaBot and the GY-85 IMU Sensor for recording yaw rate and yaw angle.

Software

PixyMonV2 is used to teach Pixy2 camera to specifiy lane tracking and enhance its vision settings using color-based filtering.

AlphaBot is coded in Ardunio C/C++.

Arduino IDE

The AlphaBot's software is created with the Arduino IDE, which offers a unified environment for writing, compiling, and uploading code to the microcontroller.

The program utilizes Arduino C/C++ and incorporates standard libraries like Wire.h for I2C communication and Pixy2I2C.h for the Pixy2 camera. The loop function operates continuously to read the sensors, compute the yaw rate and yaw angle, and manage the motors.

The Serial Monitor allows for the viewing o data in real-time (line error, yaw rate, heading, motor speeds). This data can also be monitored via Bluetooth for wirelessly.

Simulink

The AlphaBot’s behavior can be modeled, simulated, and analyzed using Simulink, a visual programming environment based on MATLAB.

Measurement

The measurement system records the robot’s navigation performance using onboard sensor.

The Pixy2 Camera for lane detection measurement.

The GY-85 IMU Sensor for measuring yaw rate and yaw angle.

Datasheet

Component	Model / Type	Key Specifications	Function in Project
AlphaBot	Waveshare AlphaBot	2 DC motors, motor driver, chassis, 6–12V power input	Mobile platform for autonomous navigation
Pixy2 Camera	Pixy2 CMUcam5	60 fps I2C/SPI/UART interface Line-tracking mode	Lane detection and position measurement
GY-85 IMU	GY-85 (HMC5883L + MPU6050)	3-axis gyroscope, accelerometer, magnetometer I2C interface	Measures yaw rate, heading, and motion data
Bluetooth Module	HC-05 / HC-06	UART interface, 3.3–5V operation, 10 m range	Wireless telemetry of sensor and motor data

SVN-Repository

https://svn.hshl.de/svn/HSHL_Projekte/trunk/AlphaBot

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