by lty4ever

Day1

note one - ways to use md

normaly we put a "#" before words for a title , "##" before a mainpoint and "*" before a list component in a list , to put in plain words , we just create a new line and type words into it.

for a link we use the following format
百度
a pair of [] which contains the word want to show with a pair of () which contains the website want to link to
[-=-]=-=(-=-)

note two - ways to use terminal in linux

press ctrl + alt + t to open terminal at Home of your user.
cd
ls: show components in this dir

type nothing after cd goes back to ~(Home)(the same use as typing ~) not only / means the root which can be used as a standard when getting into dirs , the ~ which means Home can also be used this way

mkdir

dirname to make this dir here
(-p) + dirname/dirname/dirname to make dirname/dirname/dirname here
dirname dirname dirname to make dirname dirname and dirname here

touch

used almost the same way as mkdir

gedit

filename to open filename using gedit

codename to show the usages of the code

press tab to fill in automatically according to what is already typed in

mind that there's two situation when tab is pressed 1. no conflicts occurs , fill in complished 2. conflicts occurs , nothing happens . If tab pressed a second time , all possible dirs appears with thier names.

note three - begining ros

turtle bot
open a terminal
roscore
open another terminal
rosrun turtlesim turtlesim_node
open another terminal again
rosrun turtlesim turtle_teleop_key
the third terminal must get focus

note four - basic rules of ros

the system is separated into nodes topics and the ROS Master
firstly , master should be ran
secondly , nodes are ran and regist themselves to the Master e.g. what topic they will publish or subscribe
when Master find two nodes have a bond , it gives the control to the two nodes and the nodes will get each other known
the subscriber checkout the topic continuously

note five - basic codes for ros

roscore -run master
rosrun pakagename nodename -run node and regist to the master
rostopic echo topicname -subscribe topic within this terminal
rostopic info topicname -show lists of publishers and subscribers
rostopic list -listout all the topics available
rqt_graph -show a publisher_topic_subscriber graph in the whole program

Day2

note one - ways to make a work space and a pakage

firstly , a empty dir with proper name should created (normally named as ..._ws)(should contain a sub dir named src)
secondly , get into the _ws dir
catkin_make to compile the work space
once we compiled a dir , sub dir build and devel created , src get new file CMakeLists.txt
catkin_create_pkg pakagename languagename(rospy or roscpp) to make a pakage
get into devel
source setup.bash to use socks to add bash file into environment arguements
roscd pakagename to get to a pakage dir quickly
create a dir named launch under pakagename dir
get into it and make a launch file named properly
gedit it
the format of the file should be like the one down here
<=====launch=====>
<=====node name="whatever" pkg="pakagename" type="nodename" /=====>
<=====node name="tyzl" pkg="turtlesim" type="turtlesim_node" /=====>(example , the real format should get rid of the (=====)s)
<=====/launch=====>

note two - additional code used to merge two topics

<=====node name="tyzl" pkg="turtlesim" type="turtlesim_node" (used to have a "/" here , deleted)=====> <=====remap from="original topic" to="destination topic" /=====> <=====/node=====>
rosrun topic_tools relay originalTopic destinationTopic

note three - including a launch file in another

<=====include file ="$(find pkgname)(/launch)/filename.launch"/=====> (/launch) means it is needed most of time
when a launch file includes itself , it will be forbidden even if it ran
forbidden also works when two launch file includes each other

Day3

note one - avoid controling the robot on such a small screen

review XD
plug sensors into computer through a lengthen wire (at least usb3.0) so that every thing could be seen more clearly
when errors like "no cameras detected" appears , keep the wire linked while get the computer reboot

note two - SLAM

mapping while locating
a robot starts at some where unknown , the robot moves , detects the environment , enhance a map while locate itself in the map

note three - route planning

global planning - starting point , destination , route
local planning - when crash into trouble , whether change the route/way or not
there mainly 2 algroithms used to plan a route - A* and Dijkstra's
A* is the most quickly one in the direct searching while D's is the most usual one
the main principle of the dynamic window algorithm - 1.given the state of the bot 2.according to the speed and other elements dicide the best route 3.repeat

note four - mapping

roslaunch mx_bringup rbc_camera_start.launch(or mx_btingup rbc_lidar_start.launch)
roslaunch mx_nav gmapping_demo.launch
roslaunch mx_rviz gmapping_view.launch
!!!!if robot is not moving : 1.try more controlling nodes 2.if still not work , reboot the system 3.ensure the circuit is complete (the switch is off) 4.if the same thing happens over and over , check if the motor driver is broken(happens when motor is overloaded for a time period which is too long)
avoid bumping into walls coz the map will be broken
when robot only drifts a little , it doesn't matter , some strong code will repair the damage to the maps

note five - radars

normal lidar - spins and culculates using triangular similation
solid lidar - doesn't spin and culculates diatance using [data deleted]

Day4

note one - basical python

cv2.waitKey(number) makes the program stay on this line of code till the wanted key is pressed
cv2.waitKey(0) means wait for anykey
cv2.imshow('label',a variable contains a img) pops up a form with a img titled label

note two - use python to code a ros node

the first line of program should be "#!/usr/bin/env python" or the program will not know use which program to run itself
rate = rospy.rate(Hz) using together with rate.sleep() will make the while loop run at (Hz)Hz
'I coded the program and saved it , I also sourced the bash file , why can't I find it when I press Tab in Terminal?'
the program should be set to be a executable one so that it could be found
to set program into a executable one , mouse 2 on the file in the resource manager , mouse 1 on properties , selece Permissions and put a tick in the checkbox labeled execute

note three - neural network

CNN - Convolutional Neural Network - used for image recognizing
DNN - Deep Neural Network - used for voice recognition
RNN - Recurrent Neural Network - used for writing or voice recognition
trained using different frames - tensorflow / caffe /...
the process of using neural network to classify pics/tracks/marks is separated into three steps 1.pick a frame , train a network 2.pack the net work into a graph file and post it into the movidious which we will work with so that less tine will be cost 3.post the object into the movidious and wait for a result
python two separately upgraded versions , movidious works with only python3 and at least usb 3.0
if no movidious/compute stick is inserted , the neural network could also be ran , see in the refrence section

Day5

note one - voice classifying and text_to_speech

VC , for example , contana
TTS , for example , screen reader
the wake up words are set at '~/ros_voice_system/src/baidu_speech/launch/baidu_tts.launch'
the apikey is set at '~/ros_voice_system/src/tuling_nlu/launch/tuling_nlu.launch'

note two - tuling123

sign up
create a bot
free-edition limits everyday analyzing into 1000
a private library can set the answer according to the question

note three - it chat bot (wechat auto-reply bot)

goto the website (see in the reference section)
copy the code
change the apikey into yours
python it
log-in
!!when two user both logged in , if any of them sent a message to the other , the bot will chat with each other , it's quite interesting but remember one's daily limit of analysing-responding is 1000messages!!

ref erences :

ROSNotes/RN_201808_ChenSiyuan