2019FallTeam1

Team Members

• Harou Xue - Electrical Engineering
• Yuhan Zhang - Electrical Engineering
• Cheyenne Herrera - Math/Engineering

Project Objectives

The goal of our project is to create a miniature version of a Tesla. We wanted to increase the safety of the self-driving car by implementing rear-end collision prevention as well as apply the lane change safety. The Donkey RoboCar will stop itself when approaching an object in the front using a TOF sensor mounted to it. Additionally, the car will speed up if a vehicle/object is approaching it from behind. Furthermore, the RoboCar will implement lane change on command.

Mechanical Design

Electronic Design

Components

• Jetson Nano with fan and wirless card installed
• PCA9685 PWM (control servo and ESC)
• Steering Servo (control steering)
• Electronic speed controller (ESC) (control throttle)
• Relay (provide emergency stop)
• LED (show emergency stop status)
• power
• USB camera
• Arduino (for connecting ToF sensor)
• Time-of-flight sensor (ToF)
• Lidar and USB controller

Schematic

Software

We use the Donkey Car framework for car control. With the framework, we can easily train deep learning autonomous driving models by recording manual driving.

The frameworks use modularized "parts" to manage all the components in a car. When the car runs, it loops through all parts that have been added to it.

Our project involves new sensors, ToF and Lidar, that have not been included in Donkey. They should be added to Lidar in the form of parts.

We are using YD Lidar X4

There is a python library PyLidar3 that supports this model.

The Donkey part for Lidar

<source lang="python3"> class YDLidar: # in python2 it has argument (object)

   # the lidar should be started as threaded
   def __init__(self, port='/dev/ttyUSB0'):
       from PyLidar3 import YdLidarX4
       self.port = port
       self.lidar = YdLidarX4(self.port)
       self.distances = [5000] * 360
       self.angles = list(range(360))
       self.scan = {}
       for i in range(360):
           self.scan[i] = 5000
       self.lidar.Connect()
       self.on = True
       self.scans = self.lidar.StartScanning()
       self.time = self.get_time()

   def update(self):
       while self.on:
           try:
               for scan in self.scans:
                   for i in range(360):
                       self.scan[i] = scan[i]
                   self.time = self.get_time()
           except serial.serialutil.SerialException:
               print('serial.serialutil.SerialException from Lidar. common when shutting down.')

   def run_threaded(self):
       return self.scan, self.time

   def shutdown(self):
       self.on = False
       time.sleep(2)  # give the update thread some time to shutdown
       self.lidar.StopScanning()
       self.lidar.Disconnect()

   def get_time(self):
       
       get time in milliseconds
       the granularity is ten milliseconds
       
       return time.time() * 1000

</source>

Useful Knowledge

Donkey Parts

https://www.youtube.com/watch?v=YZ4ESrtfShs

How Donkey works

https://www.youtube.com/watch?v=G1JjAw_NdnE