Fazlur Rahman

Autonomous Mobile Robot on edX: a Review

I completed my first online course several days ago. I was skeptical about this novel media of learning since it does not allow a direct touch with the professor. However, I finished my first online course and in this post I’m going to share my experience with you.

The online course that I took is Autonomous Mobile Robot on edX. This course is provided by professors from ETH Zurich, one of the best university in the world, especially for autonomous systems. To have a certificate, you have to pay an upgrade fee and complete this course within a certain time range.

The course consists of weekly overview, lecture segments, problem set, and quizzes. For every new topic, they will provide you a weekly overview on what to expect from that particular topic. Next, they have some 8-15 minutes videos to learn. It shows a slide and a handwritten notes on it. Lastly, to validate the student capability, one has to answers question from problem set and quizzes.

Discussed Topics

I learnt some new concepts from this course. Firstly, I was introduced to “Locomotion Concepts” and “Mobile Robot Kinematics”. In these topics, I learnt how to model a dynamic system such as legged and wheeled robots. I had to solve problem related to the dynamic modelling as well as its control using inverse kinematics and forward kinematics.

The following topic is “Perception”, in which they introduce me to sensors and computer visions. Essentially, this is how your robot “see” the environment. This topic is very interesting because it allows me to know how sensors, especially camera, work and how to extract meaningful information from this devices. However, the problem set does not deeply elaborate the technical aspects. They mostly asked a conceptual question on the methods for computer vision. Therefore, to understand deeply, you need to practice a lot by yourself.

After perception, next is “Localization”. This topic allows me to understand how to find a position of a robot in a known environment. They teaches some methods such as Markov and Extended Kalman Filter (EKF) Localization. From this topic, I understand localization method for both discretized and continuous environment, as well as its advantages and disadvantages.

In contrast to localization, the next topic, “Simultaneous Localization and Mapping (SLAM)” is a method to localize a robot in an unknown environment. This is one of the most critical part in today robotics. Most of the robots are deployed in an unexplored place and one has to keep track of it. For this course, they teach the basic of SLAM, which is graphical representation of robot states and environment’s features. Then they explain further on the optimization of SLAM and elaborate it for EKF SLAM.

Surprisingly, after this completing this topic, I had an interview with a Japanese drone company. They asked me a lot of things related to drone and its automation , including SLAM. After explaining the EKF SLAM that I studied, they said they’re not using it in their company and they explain briefly on what they’re working on. This opened my mind that there are a lot of SLAM method out there and this course only covers a small part of it.

The last topic of this course is “Planning”, in which they teach you how a robot can navigate from a start to a specified goal. For this topic, they provided me a lecture on potential field planning as well as A*. On the problem set, one to solve a planning exercise using both methods. However, the planning problem is not integrated with the “actuation” part. In my opinion, elaborating it allows the student to understand deeply how it works in real life.

Review

In my opinion, this is a good starting point to learn about robotics. One can build a basic knowledge and sense after finishing this course. The problem set is really helpful to understand the concept and validate your knowledge. They also provide you with two quizzes, which are harder than the problem set.

However, some questions in the problem set are not well defined, making it harder to solve it as you are not certain on what is expected and the format of your answer. Wrong formatting will lead to a wrong answer.

The courses is also not well maintained, one probably has answer to his/her question after a few weeks. This makes students find difficulties to continue their progress. I assume this thing happened because the course is launched long time ago and not a lot of people doing it right now.

Overall, as long as one has the required basic to do this course, such as mathematics and basic programming, it is a good introduction to robotics. Oh, and here’s my certificate from the online course! Check out this photo below or this link!

Programming for Robotics – ROS: Exercise 3

This post is a continuation of previous project, on learning ROS. The lecture and exercise is given by Robotic Systems Lab. – ETH Zurich, can be accessed through this website.

This time, the exercise goal is to make the robot hit the pillar in the simulation environment. The pillar position is found by measuring closest distance from LIDAR measurement. The speed is set to be constant and a simple P controller is made to direct Husky towards the pillar. Both speed and P-gain is written in param file, making it easy to tune avoiding re-build the code. A marker in RViz is created to visualize location of the pillar.

Exercise 3

The video above shows my result for the exercise. You can find the exercise paper sheet on this link.

Thanks to Robotic Systems Lab – ETH Zurich for sharing this helpful course!

Kiai Hologram oleh Emha Ainun Nadjib

Kiai Hologram adalah buku Cak Nun kesekian yang saya baca. Saya membaca buku beliau karena tertarik dengan cara beliau memandang suatu peristiwa. Dari buku-bukunya, saya belajar mengambil hikmah.

Seperti buku-buku sebelumnya, beliau menghikmahi kejadian-kejadian di sekitarnya. Kali ini, selain tentang kemasyarakatan, beliau juga sedikit bercerita tentang keluarganya di bagian pertama buku ini. Selain itu, beliau membagikan pemikiran-pemikiran yang dibahas selama acara kenduri cinta, atau maiyah-an.

Ada beberapa kutipan menarik yang saya ambil dari buku ini, termasuk paragraf berikut.

Pribumi itu bukan siapa kita, apa warna kulit kita, apa agama kita. Pribumi itu bukan personalitas, bukan pula identitas. Pribumi itu komitmen kepada rakyat karena kita sendiri adalah rakyat, bukan yang berkuasa atas rakyat.
Hal. 219

Paragraf tersebut saya artikan sebagai sindiran bagi pemimpin yang datang dari kalangan “rakyat”, namun kemudian menjadi “elitis”. Kebijakan-kebijakan yang dibuat tidak lagi memihak kepada “rakyat”, sehingga boleh kita mengeluarkan personil tersebut dari himpunan “rakyat”.

Di halaman lain, saya menemukan satu hal berkaitan dengan ketuhanan-keagamaan yang menambah wawasan saya.

Kalau manusia mencari Tuhan, itu namanya rasa keagamaan atau religiositas (berkaitan dengan ibadah muamalah). Kalau Tuhan menginformasikan, menghidayahi, menyuruh, melarang, itu namanya agama atau religion (berkaitan dengan ibadah madhloh). Tanda agama adalah kalau ada ibadah madhloh. Karena kalau ibadah muamalah, meskipun juga baik, ia bukan agama melainkan rasa keagamaan.
Hal. 275

Buku-buku Cak Nun memang mengandung banyak hikmah yang bisa kita pelajari. Namun, sebagai pembaca non-jawa, saya merasa ada beberapa kata dalam bahasa Jawa yang seharusnya dibuatkan pengartiannya dalam bahasa Indonesia. Saya mahfum bahwa tidak semua kata dalam sebuah bahasa dapat dengan mudah diartikan ke bahasa lain, tapi membiarkan pembaca tersesat sedikit mengurangi kedekatan pembaca dengan buku.

Programming for Robotics – ROS: Exercise 2

This post is a continuation of previous project, on learning ROS. The lecture and exercise is given by Robotic Systems Lab. – ETH Zurich, can be accessed through this website.

This second lecture is focused on ROS package structure, ROS C++ client library, ROS subscribers and publishers, ROS parameter server, as well as RViz visualization. I haven’t included integration and programming with Eclipse in my work.

Exercise 2

The video above shows my result for the exercise. You can find the exercise paper sheet on this link.

Thanks to Robotic Systems Lab – ETH Zurich for sharing this helpful course!

Programming for Robotics – ROS: Exercise 1

Recently, I found an interesting website to learn about ROS and Gazebo. This website is provided by Robotic System Lab – ETH Zurich. Even though I’ve made several ROS project, including the one for my internship at ProtoSpace Toulouse – Airbus, the online course has a lot to offer about ROS.

The first lecture is an introduction to ROS, such as masters, nodes, topics, and launch files. The lecture file can be found in this link. At the end of the lecture, an exercise is given which require students to control a simulation in gazebo using keyboard input as well as to make a launch file.

Exercise 1

The video above is a simulation of the exercise, controlled by keyboard using teleop_twist_keyboard.

Obstacle Avoidance for Quadcopter with Ultrasonic Sensor

In 2017, I made an obstacle avoidance for quadcopter using an ultrasonic sensor as my undergraduate thesis project. The goal is to do proof of concept of an ellipsoid based guidance proposed in the following paper. The paper take a fixed-wing aircraft as the model. However, since implementing it on a fixed-wing model is an extremely laborious work, the implementation is done on a quadcopter.

To mimic the radar sensing, in this project, I used an rotating ultrasonic. The ultrasonic is rotated by using a servo that is commanded through a microcontroller, Arduino. The sensing result is estimated as an ellipsoid geometry, considering the size and orientation of the obstacle as well as aircraft velocity vector. A contact point is set as a guidance.

List of Prime Numbers

Recently I had an interview for an internship position with Volocopter. It is an Urban Air Mobility (UAM) company based in Germany. As far as I know, this company is one of the most advance in UAM competition.

One part of the interview was an online coding. The interviewer asked me to “provide a list of all prime number up to 1000”. I found this question interesting as a there’s only one characteristic of a prime number.

About Me

Hi! My name is Fazlur. I’m majoring Aircraft System and Control at ISAE Supaero, Toulouse, France. I studied Aerospace Engineering in Institut Teknologi Bandung (ITB), Bandung, Indonesia.

I’m interested in Unmanned Aerial Vehicle, Automatic Control, and Robotics. Still progressing to make a masterpiece on these topics!

I have no specific hobbies. I play futsal weekly. I love cooking, my friends told me I’m good at it. Sometimes I make a miscellaneous DIY project to spend time.

I speak Indonesian (my native language), English, and French. I’m learning German at this moment.

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