# Human body movement equations

1. Apr 28, 2010

### Sara_So

please can any one help me to figure out the equations of human body movement ( walk )

I am in need so badly ..

Best Wishes

2. Apr 28, 2010

### Staff: Mentor

What is the context of your question? What is the application?

3. Apr 28, 2010

### LostConjugate

It is so complicated that we still use motion capture tech in all the blockbuster video games and movies.

4. Apr 28, 2010

### Sara_So

I want them to model the human body in walk mode for a computer graphic project

5. Apr 28, 2010

### LostConjugate

Even the most expensive programs such as Maya and 3D studio max do not come with an engine that can do this yet. In other words there is no equation. The way developers do it is by playing around with it until it looks good, but it never looks as good as motion capture.

You could download a motion capture function, but there will be no equation behind it.

6. Apr 28, 2010

### Sara_So

ok.. it seems so difficult
how can i use the motion capture ? if you can tell me please ..

7. Apr 28, 2010

### LostConjugate

8. Apr 28, 2010

### Sara_So

Thank you very much ..

9. Apr 28, 2010

### eveo

Looks like I've got some work to do :P

10. Apr 28, 2010

### mikeph

Doesn't seem too hard in principle...

Each joint has a maximum of 2 angular values associated with its configuration- I count about 14 important joints used in walking (wrists,elbows,shoulders,neck; torso, upper legs-pelvis, knees, ankles). The walking motion should be roughly captured in a time-evolution of these ~28 parameters. Assuming each one is sinusoidal (and therefore has 3 parameters: amplitude, frequency and relative phase) you will have 28*3 - 1 total parameters if you define eg. the neck to be phase 0.

The hard part I guess would be illustrating that your results are correct since a bunch of numbers is hard to compare to the actual walking motion! I guess you will just study a human walk and a few simple measurements should give you the answers.

11. Apr 29, 2010

### Sara_So

you simplify the idea in nice way :)

but can you help me to find the equations of those joints ??

12. Apr 29, 2010

### mikeph

Try to think about the interdependence of these joints. For example, you can move your neck independently from your wrist, but surely it is easier to bring your knee towards your chest if your knee itself is bent (ie. kneeling and bending forward, compared to having straight forward legs and bending forward!).

Of course this varies between humans, depends on muscle "temperature" (ie. ROM is greater if you have warmed up), and also on time (so you can kick higher than you can keep your leg held up because the muscle has some elasticity). After this you might even factor in geometry arguments and constraints such as balance (keeping the centre of mass in a position that the legs provide sufficient torque to prevent a fall!).

It is tricky but sounds like an interesting project! I think it comes under biomechanics (which I have never studied... so I advice you check out some textbooks before you listen to me)

13. Apr 29, 2010

### Sara_So

I am greatful ..

Thank you every one (F)..