Let's Make Robots! | RobotShop

Mobile robot -- Dzik Rover


Intro

  Hello to everyone :) I'm Łukasz and I want to share with you the process of design and building my robot Dzik Rover. It's my very first project, therefore some things in it I had to do a couple of times :P  just a trial and error method until I get fine solution of the problem.

Project was divide on stages:

  • searching for the right parts and design mechanical part by Autodesk Inventor 2016
  • workshop work on mechanincal construction part of the project
  • design PCB board by Autdesk Eagle
  • workshop work on electronic and electric part of the project
  • write basic software which allowing to control robot from PC level
  • tests

Additional link:

Specs:

  • dimensions(w,l,h):
    - 300x400x160 mm, box
    - 550x530x300 mm, box with wheels
  • weight: 11 kg
  • control method: manual via WiFi
  • actuators: 4 DC motors with metal gear
  • CPU: Raspberry Pi 3b, Atmega328P
  • power source: 18650 packets: 2x 4S2P for motors, 1x 2S4P for logic
  • programming language: C/C++

Mechanical part

  • 4 whell drive
  • independent suspensio
  • bearing axles

scheme of the suspension system

scheme of the suspension system

 

four bearing units are the main components of the rover's suspension

 

mounting screw of the swingarm with the port for wiring, made by lathe and table drier

 

routing the wires to the motor

 

suspension system

 

scheme of the drive system

 

drive axle mounted on the drive shaft

 

the way of mounting wheel on drive axle

 

Power-supply system

  • independent supply for logic and motors
  • XL4015 as step down voltage conventer
  • three fuses for each battery pack

power-supply system

 

Electronics

  • self-made PCB board, which is an extension board for Raspberry Pi
  • Raspberry Pi 3b:
    - main unit
    - direction control of motors
    - communication with workstation via UDP
    - communication with Atmega328P via SPI
    - communication with PCF8591 via I2C
  • Atmega328P:
    - PWM generator
    - speed control
    - collect information about the speed from encoders
  • VNH2SP30
    - motor driver
  • PCF8591
    - sending information to the Raspberry Pi about current consumption of motors
    - sending information to the Raspberry Pi about batteries voltage level
  • LM339N
    - using as a low level support for encoders

 

hardware architecture

 

PCB board model

 

Software

  • Atmega328P -- Eclipse IDE for C/C++
  • Raspberry Pi 3b (Rasbian) -- Adafruit webIDE, library: Wiring Pi and Qt 5.7.0
  • Desktop application (Windows 10) -- Qt Creator 4.1.0, library: Qt 5.7.0

block diagram of the desktop application 

Summary and my questions

Work on rover allowed me to expand my knowledge and skills, project is still open. I dropped on github: Inventor and Eagle files and also source code. I will be happy to answer any questions you may have :) if I could ofcourse ;). But first, I have some questions: 

  • I get strange outcome from encoders output, I know that I have a mistake in Schmitt Trigger module ( forget about feedback), but some encoders seems to work fine and some not, let me show that on the pictures. Maybe someone had the same issue?

  • When I was doing the tests, I damaged two motors (gear ratios), therefore I want to replace the motors. I think about wiper motors, so what do you think? Is it good idea?

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Nice project and great work in CAD and PCB.

Regarding your questions. That's certainly an interesting encoder issue. You might want to investigate the following: status of your encoder disks (physically); create a small bit of code to only read the encoders (no other functions) to see if there is something causing delays.

As to the wiper motors, they are commonly used in robotics, but I cannot get a general sense of size of the robot to know if thye would be appropriate. If the gears stripped, the motor(s) you had were underpowered. Note too that your wheels are far apart which makes turning on the spot quite hard.

Thanks a lot :)

I updated some info about the rover. Now the highest priority is motor replacement. Problem with encoders I put aside now. Today I got one wiper motor, when I tested it, I will share some info.