2019WinterTeam2

Team 2 attempted to achieve object avoidance by incoorporating a 360° RPLIdar along with the camera, and controlling their operation using ROS (Robot Operating System).

Introduction

Welcome to team2 ECE148 Wiki page. In this class, we build and utilized a remote-controlled car. In this page, we will cover the details behind the design of the RC car and demonstrate results. The goal in this class was to perform the following tasks:

• Autonomously drive on an indoor track
• Autonomously drive on an outdoor track
• Obstacle avoidance using RPLidar and ROS

Team Members

• Chen Du (ECE grad)
• Jingying Chen (MAE undergrad)
• Marshall Garcia (MAE undergrad)
• Tina Kafel (ECE undergrad)

RC Car details

• RC Car hardware:

Here is a detailed list of the hardware used in the project:

RC Car BOM(Bill of Material)

Part Name	Part Number	Datasheet	Manufacturer	Qty	Unit Price	Purchase Link	Purpose in RC Car
ESC	SBEC ESC 60a	Datasheet	QuicRun
PWM Controller	PCA9685	Datasheet	Adafruit
USB Module	HW384	Datasheet	SheoIseven
Motor	RS540	Datasheet	Tamiya
Blue/Red LED	APM External	Datasheet	Kingduino
Main Switch	T/XT60/EC3 Plug	Datasheet	Banggood
Chasis	TT01 TT01E	Datasheet	Radcat
RGB LED	N/A	Datasheet	MakerLab
Relay	KR1201A-4	Datasheet	QIACHIP
Raspberry Pi	Model 3 b+	Datasheet
RP Camera	913-2664	Datasheet	Raspberry Pi
"11.1 V 3 cell LiPo"	XT-60	Datasheet	Turnigy
Voltage Reader	EC	NA	BX100
Servo Motor	MG995	Datasheet	N/A

• RPLidar

What is an RPLidar? Lidar is a device that measures the distance to a target by sending pulsed laser beams and receiving the reflected beams with a sensor. The accuracy of lidar is higher than other sensors of similar nature, such as an IR sensor or an ultrasonic sensor. An RPLidar is a 360-degree 2D lidar.

What are the different types of RPLiDAR?

• The RPLidar used in our project is the A1M8 12M range model. A1M8 is based on laser triangulation ranging principle and uses high-speed version acquisition and processing hardware. This system measures distance data more than 8000 times per second.
• The other model
• The other other model

• RPLiDAR and Raspberry Pi

• ROS and RPLidar

Upon every connection to a USB port, sudo permission to access the serial port for the lidar must be granted. In the Linux operating system, the command to list the responsible port and granting permission would be the following:

ls -l /dev |grep ttyUSB#lists the port connected to the LiDAR

sudo chmod 666 /dev/ttyUSB0#grants permission to write to USB0

To test the RPLiDAR within ROS, we can run the rplidar node and view the realtime readings and mappings:

roslaunch rplidar_ros view_rplidar.launch#running the RPLiDAR live feed

An example of an RPLiDAR scanning the room

rosrun rplidar_ros rplidarNodeClient#read values from LiDAR

The lidar scan values can be read by subscribing to rplidar_node topic:

A live read of the RPLiDAR Scans and relevent topics

Viewing graphs of ongoing scans on the roscore primary node can be viewed using a ros rqt graph generator:

A rqt graph of RPLiDAR subscriber and publisher to the scan topic