SLAM-backend-tutorial

You could see the Video lecture on Youtube.

The original code, slides, and notes are available in Google drive.

slam_tutorial/ folder involves my personal solution,
and slam_tutorial_solution/ involves given solution.
The contents are almost similar.

I test this repository on Ubuntu 18.04.

Contents

How to make same enviornment with Docker.
How to execute this code.
Result
Contact

How to make same enviornment with Docker.

First you have to install Docker.

1. Just clone this repository and change the directory path.

git clone https://github.com/Taeyoung96/SLAM-backend-tutorial.git  
cd SLAM-backend-tutorial

2. Build the SLAM docker image.
This docker image includes ubuntu 18.04, ros melodic, ceras-solver, and gtsam.

docker build -t tutorial-week-2020/slam:latest .

When you are finished, check the image.

docker images

You can check that the image is created as below in your terminal, the IMAGE ID and CREATED TIME may be different.

REPOSITORY                TAG        IMAGE ID       CREATED         SIZE
tutorial-week-2020/slam   latest     18d7778e6a07   22 hours ago    1.46GB
ros                       melodic    2529d0ef4064   2 weeks ago     1.28GB

3. Start a Docker container while sharing the container's volume directory with a local directory.

docker run -v ${CODE_DIR}/slam_tutorial:/root/slam_ws/src/slam_tutorial -n slam_tutorial -it tutorial-week-2020/slam:latest

When you following above command, you share the slam_tutorial/ folder.
If you want to change with slam_tutorial_solution/,
just change the directory slam_tutorial/ to slam_tutorial_solution/ when you run the above command.

In my case, ${CODE_DIR} is /home/taeyoung/Desktop/SLAM-backend-tutorial/, it may depend on where you clone the repository.
For example,

docker run -v /home/taeyoung/Desktop/SLAM-backend-tutorial/slam_tutorial:/root/slam_ws/src/slam_tutorial -n slam_tutorial -it tutorial-week-2020/slam:latest

When the container creation is completed, the terminal path is changed and you can see that you are connected to the docker container.

root@bf318ac3a3d7:~#

Check the directory in the container and the local directory are shared.

root@bf318ac3a3d7:~# cd slam_ws/
root@bf318ac3a3d7:~/slam_ws# cd src
root@bf318ac3a3d7:~/slam_ws/src# ls
CMakeLists.txt  slam_tutorial

How to execute this code.

1. Just build the code with catkin_make

root@bf318ac3a3d7:~/slam_ws# catkin_make

After the build is complete, you can see the output as below and a build folder and a devel folder are created.

Scanning dependencies of target ceres_spg
Scanning dependencies of target gtsam_spg
[ 25%] Building CXX object slam_tutorial/CMakeFiles/ceres_spg.dir/src/ceres_spg.cpp.o
[ 50%] Building CXX object slam_tutorial/CMakeFiles/gtsam_spg.dir/src/gtsam_spg.cpp.o
[ 75%] Linking CXX executable /root/slam_ws/devel/lib/slam_tutorial/ceres_spg
[ 75%] Built target ceres_spg
[100%] Linking CXX executable /root/slam_ws/devel/lib/slam_tutorial/gtsam_spg
[100%] Built target gtsam_spg

2. Execute the code with rosrun command.

You could execute two different node. One is for Ceres-solver example, the other is for gtsam example.

If you want to run the ceres-solver example node, you enter the following command.

rosrun slam_tutorial ceres_spg

If you want to run the gtsam example node, you enter the following command.

rosrun slam_tutorial gtsam_spg

Result

Result output when you run ceres-solver example node

You could visualize .csv files, with Matlab.
I got different results because I designed the error function differently.

Initial pose

Optimized_pose with my personal solution

Optimized_pose with given soltion

Solver Summary (v 1.14.0-eigen-(3.3.4)-lapack-suitesparse-(5.1.2)-cxsparse-(3.1.9)-eigensparse-openmp-no_tbb)

                                     Original                  Reduced
Parameter blocks                          552                      550
Parameters                               1932                     1925
Effective parameters                     1656                     1650
Residual blocks                          1073                     1073
Residuals                                6438                     6438

Minimizer                        TRUST_REGION

Sparse linear algebra library    SUITE_SPARSE
Trust region strategy     LEVENBERG_MARQUARDT

                                        Given                     Used
Linear solver          SPARSE_NORMAL_CHOLESKY   SPARSE_NORMAL_CHOLESKY
Threads                                     1                        1
Linear solver ordering              AUTOMATIC                      550

Cost:
Initial                          2.716861e+02
Final                            5.204096e+00
Change                           2.664820e+02

Minimizer iterations                      161
Successful steps                          149
Unsuccessful steps                         12

Time (in seconds):
Preprocessor                         0.000880

  Residual only evaluation           0.026268 (161)
  Jacobian & residual evaluation     0.265551 (149)
  Linear solver                      0.838873 (161)
Minimizer                            1.193949

Postprocessor                        0.000041
Total                                1.194870

Termination:                      CONVERGENCE (Function tolerance reached. |cost_change|/cost: 8.268293e-07 <= 1.000000e-06)

Result output when you run gtsam example node

Factor Graph:
size: 6

Factor 0: PriorFactor on x1
  prior mean:  (0, 0, 0)
  noise model: diagonal sigmas[1; 1; 0.1];

Factor 1: BetweenFactor(x1,x2)
  measured:  (5, 0, 0)
  noise model: diagonal sigmas[0.5; 0.5; 0.1];

Factor 2: BetweenFactor(x2,x3)
  measured:  (5, 0, -1.57079633)
  noise model: diagonal sigmas[0.5; 0.5; 0.1];

Factor 3: BetweenFactor(x3,x4)
  measured:  (5, 0, -1.57079633)
  noise model: diagonal sigmas[0.5; 0.5; 0.1];

Factor 4: BetweenFactor(x4,x5)
  measured:  (5, 0, -1.57079633)
  noise model: diagonal sigmas[0.5; 0.5; 0.1];

Factor 5: BetweenFactor(x5,x2)
  measured:  (5, 0, -1.57079633)
  noise model: diagonal sigmas[0.5; 0.5; 0.1];


Initial Values:

Values with 5 values:
Value x1: (gtsam::Pose2)
(0.2, -0.3, 0.2)

Value x2: (gtsam::Pose2)
(5.1, 0.3, -0.1)

Value x3: (gtsam::Pose2)
(9.9, -0.1, -1.77079633)

Value x4: (gtsam::Pose2)
(10.2, -5, -3.04159265)

Value x5: (gtsam::Pose2)
(5.1, -5.1, 1.47079633)

Initial error: 18.510326
newError: 0.122934358
errorThreshold: 0.122934358 > 0
absoluteDecrease: 18.3873916591 >= 1e-05
relativeDecrease: 0.993358606565 >= 1e-05
newError: 8.85829965247e-06
errorThreshold: 8.85829965247e-06 > 0
absoluteDecrease: 0.12292549938 >= 1e-05
relativeDecrease: 0.999927942848 >= 1e-05
newError: 3.68234840295e-15
errorThreshold: 3.68234840295e-15 > 0
absoluteDecrease: 8.85829964879e-06 < 1e-05
relativeDecrease: 0.999999999584 >= 1e-05
converged
errorThreshold: 3.68234840295e-15 <? 0
absoluteDecrease: 8.85829964879e-06 <? 1e-05
relativeDecrease: 0.999999999584 <? 1e-05
iterations: 3 >? 100
Final Result:

Values with 5 values:
Value x1: (gtsam::Pose2)
(-1.27918496267e-18, 1.66618678917e-19, -3.14163502147e-20)

Value x2: (gtsam::Pose2)
(5, 5.11915975726e-20, -7.11636343752e-20)

Value x3: (gtsam::Pose2)
(10.0000000015, -4.40576423166e-09, -1.5707963267)

Value x4: (gtsam::Pose2)
(10.0000000114, -5.00000003139, 3.14159265352)

Value x5: (gtsam::Pose2)
(4.99999999784, -5.00000000264, 1.57079632663)

x1 covariance:
                 1 -1.71241483502e-17 -5.65095102146e-17
-1.71241483502e-17                  1   1.7763568394e-16
-5.65095102146e-17   1.7763568394e-16               0.01
x2 covariance:
              1.25 -3.79952940193e-16 -1.40205920175e-16
-3.79952940193e-16                1.5               0.05
-1.40205920175e-16               0.05               0.02
x3 covariance:
     2.70000000047 -8.21536053911e-10    -0.155000000029
-8.21536047854e-10      1.45000000006  -0.00499999990562
   -0.155000000029  -0.00499999990562    0.0264999999985
x4 covariance:
   2.1125000074  0.800000006448 -0.120000000784
 0.800000006448   2.80000000387 -0.170000000296
-0.120000000784 -0.170000000296 0.0279999999952
x5 covariance:
  1.69999999991 -0.224999999954 0.0449999999659
-0.224999999954   2.06250000049 -0.127500000037
0.0449999999659 -0.127500000037 0.0264999999968

Contact

If you have any question, feel free to send an email.

TaeYoung Kim : tyoung96@yonsei.ac.kr

Taeyoung96/SLAM-backend-tutorial

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