Figure 2.
Error amplification for throwing depends on the target location and planning errors. (a) For two different targets, one below and another above the shoulder, a comparison between all possible overarm (solid red) and underarm (dashed green) throws. Accuracy is quantified by the inverse of the non-zero singular value, i.e. p=1/λ of the map Jerr given by equation (3.1) as a function of the release velocity ω. (b) Polar plots of accuracy p(ϕ)=1/λ(ϕ) as a function of arm angle at release ϕ for the same two different targets. We see that even if p(,ωm,ϕm) is a maximum, it can fall off quickly, so that such a strategy is susceptible to small planning errors, i.e. inaccuracies in the internal model of the dynamics.