Convert a video from MOV to mp4:
ffmpeg -i input.mov -qscale 0 output.mp4

Trim a video in seconds:
ffmpeg -ss 00:01:00 -to 00:02:00 -i input.mp4 -c copy output.mp4

Options:

• -i: This specifies the input file. In that case, it is (input.mp4).
• -ss: Used with -i, this seeks in the input file (input.mp4) to position.
• 00:01:00: This is the time your trimmed video will start with. The timing format is: hh:mm:ss
• -to: This specifies duration from start (00:01:40) to end (00:02:12).
• 00:02:00: This is the time your trimmed video will end with.
• -c copy: This is an option to trim via stream copy. (NB: Very fast)

Maintaining balance is one of the crucial things for roboticists working with mobile robots, especially with humanoid robots. An example of a walking HRP-2 robot is shown in the teaser figure.

When a foot sole of HRP-2 is in contact with a surface, for example, the ground plane, the contact must remain fixed because otherwise the robot is at risk of falling. Therefore, it is of key interest to derive what we call the contact stability condition for such type of fixed contact.

In this article, we consider the contact point $p_k$ located at the right foot sole of HRP-2 in the teaser example. We discuss the contact stability condition of this point contact model followed by its linear approximation.

I spent four wonderful holidays in Santorini, Greece from June 17 to 21, 2023, to enjoy the sunlight and the beach! The sunset of Oia on the island is considered to be one of the most spectacular ones in the world.

It was a lot of fun sailing in the beautiful Aegean Sea. It was such an unforgettable experience!

The beautiful castle is 15 kilometers from Tour to the south. It is known for its fairy-tale entrance through flowers and trees. My wife and I planned to organize our wedding ceremony in this castle situated in the heart of Loire Valley in Central France. We were very excited to be able to reserve this venue for October 1st, 2020.

In the previous post, we have shown how angular velocities and rotation matrices are linked through the exponential map, or to be specific, the Rodrigues’ rotation formula. In this post I would like to give as an useful application of Rodrigues’ formula, to compute the rotation matrix between two vectors.

Let $a,b\in\mathbb{R}^3$ ($a\neq b$) be two unit vectors expressed in an arbitary coordinate frame. Our goal is to compute the rotation matrix from $a$ to $b$.