Technical Physics on Gateway240

Low-pass filtering in OpenSim

Tue, 31 Mar 2026 00:00:00 +0000

In the previous post, we discussed preprocessing data with OpenSim. An important part of preprocessing is low-pass filtering of various pieces of data. In this post, we will explore many of the unanswered questions and ambiguities of low-pass filtering in OpenSim. Following stories and personal experience of strange and erroneous results coming from OpenSim filtering, I began to doubt the implementation in OpenSim. To verify the results, I set out to validate the filtering against 2 existing implementations in Python and Matlab.

Preprocessing Laboratory Data for OpenSim and AddBiomechanics

Tue, 24 Feb 2026 00:00:00 +0000

In the previous post, we discussed setting up AddBiomeachanics for local data analysis. In this post, we’re going to from freshly collected laboratory data to motion reconstructions in OpenSim or AddBiomechanics. The Kuopio Gait dataset and Kuopio Full-Body (KFB) dataset were both collected in the HUMEA laboratory at the University of Eastern Finland. Using this data in downstream processing application, like OpenSim, requires preprocessing from the laboratory coordinate system and units to OpenSim’s coordinate system and units.

Reconstructing Human Motion Locally: AddBiomechanics Bilevel Optimization

Thu, 19 Feb 2026 00:00:00 +0000

What is AddBiomechanics?

In order to analyze motion capture data to create reconstructions of human motion, it is necessary to create scaled models, and calculate inverse kinematics (IK) and then inverse dynamics (ID). This process is tedious and often quite time-consuming. During the process, it is important to consider the marker residual error as well as the force residual error from force plates. This often necessitates manual tweaking to markers and model parameters to achieve a required error tolerance.

Building OpenSim and Python Wheels from Source

Wed, 18 Feb 2026 00:00:00 +0000

What is OpenSim

Perhaps you have used OpenSim for muskuloskeletal modeling. Now you have found yourself here wondering how to build the project from source and what a python wheel is. To begin, building the project from source is no small feat and usually takes many hours of configuration and troubleshooting. If you succeed in this quest, you will emerge victoriously with a working python environment with the exact dependencies that you need. A Python wheel is simply a binary package which includes all the dynamic libraries a package needs to function on your platform so you don’t have to build everything from source. For more information on Python wheels check out this article. The point of this article though is to learn how to build the wheel, so we will of course be building everything from source.

Technical Physics Dictionary in Finnish and Russian

Sun, 23 Mar 2025 00:00:00 +0000

New Specialty Words

While learning a new language is riddled with challenges, one of the most difficult riddles is properly determining all of the specialty, subject-specific words that are required in certain disciplines. This can sometimes be achieved by reading literature but is often only properly achieved by asking a native speaker.

This is a dictionary I have created to accompany an upcoming presentation regarding my research—in Finnish. Although the presentation is in Finnish, I would like to understand how to discuss this topic in all the languages I am trying to learn. Hopefully someday this list will also include French, but that’s a quest for another day. The list is presented in alphabetical order using the English words (disregarding case).