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:
- The RC car is designed with a few simple modules. Here is a detailed list of parts used in the RC car:
| Part Name | Part Number | Datasheet | Manufacturer | Qty | Unit Price | Purchase Link | Purpose in RC Car |
|---|---|---|---|---|---|---|---|
| ESC | SBEC ESC 60a | Datasheet | QuicRun | 1 | $19.99 | Purchase Link | Controls the DC motor using PWM controlled by Raspberry Pi |
| PWM Controller | PCA9685 | Datasheet | Adafruit | 1 | $14.95 | Purchase Link | Raspberry Pi doens't have many PWM GPIOs, therefore we use this module to control multiple PWM devices. Connects to RP via I2C protocol |
| USB Module | HW384 | Datasheet | SheoIseven | 1 | $6.99 | Purchase Link | Connects the LiPo battery to RPi. Includes a 5V regulator |
| Motor | RS540 | Datasheet | Tamiya | 1 | $17.30 | Purchase Link | DC motor for the rear wheels |
| Blue/Red LED | APM External | Datasheet | Kingduino | 1 | $4.04 | Purchase Link | Indicates state of the relay |
| Main Switch | T/XT60/EC3 Plug | Datasheet | Banggood | 1 | $5.60 | Purchase Link | Turns on the ESC and relay |
| Chasis | TT01 TT01E | Datasheet | Radcat | 1 | $128.49 | Purchase Link | Car skeleton |
| RGB LED | N/A | Datasheet | MakerLab | 1 | $34.75 | Purchase Link | Indicates drive mode |
| Relay | KR1201A-4 | Datasheet | QIACHIP | 1 | $7.69 | Purchase Link | Enables ESC. In the system for safty. Controlled by a remote controller |
| Raspberry Pi | Model 3 b+ | Datasheet | Raspberry Pi | 1 | $38.30 | Purchase Link | Computer controlling all components |
| RP Camera | 913-2664 | Datasheet | Raspberry Pi | 1 | $23.90 | Purchase Link | Camera compatible with RPi |
| "11.1 V 3 cell LiPo" | XT-60 | Datasheet | Turnigy | 1 | $16.37 | Purchase Link | Battery powering the system |
| Voltage Reader | EC | NA | BX100 | 1 | $13.39 | Purchase Link | Reads LiPo voltages for each cell. |
| Servo Motor | MG995 | Datasheet | N/A | 1 | $5.21 | Purchase Link | Used to control steering |
- RC Car ELectrical Connections
- RC Car Software
The software used in the project is open source.
ROS Project
- 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 LiDARsudo chmod 666 /dev/ttyUSB0#grants permission to write to USB0
- 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:
- 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
- To test the RPLiDAR within ROS, we can run the rplidar node and view the realtime readings and mappings:
rosrun rplidar_ros rplidarNodeClient#read values from LiDAR
The lidar scan values can be read by subscribing to rplidar_node topic:
Viewing graphs of ongoing scans on the roscore primary node can be viewed using a ros rqt graph generator:
