Open Sim

opensim is a biomechanics simulator for the human body. for our first usage of it, we modified different movements of the body in order to simulate a karate pose. We didn't get very complicated with the software, as its capable of everything we did with Kinovea, tracking motion based off a video alone, but is also capable of simulation like fusion360 with Finite Element Analysis. It is also able to go further than these as it can use trackers built for the human body to understand how the forces were pushing based on that data

Steps to make the karate pose:

Increase hip flexion, this moves the entire leg away from the body
decrease knee angle, this causes the knee to move back towards the body, but leaves the thigh in the air
decrease ankle angle, this causes the foot to twist back towards the body, but does nothing to the knee or thigh

Tutorial 1

1a. the right leg has 7 points of rotation, each one having 1 degree of freedom. Focusing on the hip, it can move in 3 degrees of freedom. Those 3 degrees are away(x) sideways(y), and rotate around itself(z)

1b. comparing myself to the simplified version, I have 3 more degrees of freedom, those being slightly translating the entire leg without moving my body.

Moving the hip

Showing a specific muscle

Tutorial 1.2

4a. I think it would, as when you flex a muscle you are contracting it, which would cause the muscle fiber length to be lower

4b. When starting the turn higher, the muscle starts out more contracted from having to lift the leg up. This means that it has less space to contract, and therefore cannot get up as high

Tutorial 1.3

6a. Comparing the motion of the two gaits, the crouching walk is much more unstable looking, having a lot of bent legs. Also, it shakes more than a normal gate.

OpenSim 4.5 2025-03-27 13-59-11.mp4

Comparing the knee angle of the two gaits, the crouch (blue) stays around the same angle the entire time, while the red goes around widely. Looking back at the video, this is clearly prooved

Tutorial 2

Flexors

Displaying a specific muscle group

extensors

Radial Deviators

Ulnar Deviators

Wrist extension is responsible for positive angles, or away from the body. This is visible as the extensors are on the positive side of the muscle, and they pull it up away from the ground
For the same reason as above, the radial deviators are responsible for positive motion. They are on the side away from the body, and when they contract they move the hand away from the body.
The ECU, visible on the close right looks like it is responsible for wrist extension as well as radial deviation as it is right on the top of the wrist
The ERCB, visible on the far right looks like it is only responsible for wrist extension, as it connects straight from the top to the bottom of the wrist

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