IK Example with two bones

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Inverse Kinematics Techniques in Computer Graphics: A Survey. A. Aristidou et al. STAR EG. 2017.

Two solutions defined by

- \(\displaystyle \cos(\theta_1)=\frac{l_1^2+x^2+y^2-l_2^2}{2 l_1 \sqrt{x^2+y^2}}\)

- \(\displaystyle \cos(\theta_2)=\frac{l_1^2+l_2^2-(x^2+y^2)}{2 l_1 l_2}\)

In general the general case \(\displaystyle p_k = f(\theta_i)\)

- Look for \(\theta_i = f^{-1}(p_k)\)
- \(f\) is a non linear function
- There may exists multiple solutions (or none)
- Solutions may exhibits discontinuities
- Closed form solution are not available

Some attempts for explicit solutions in specific cases

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