His 6 axis robot arm is certainly a strong first step on that road. As many people have learned, DIY robot arms are pretty difficult. [Dan]’s arm has the additional complexity of being 3D ...

and are positioned at an angle θ i (with respect to the horizontal axis), for i = 1, …, 4. The response is the distance from the end of the robot arm to the origin, on the (u, v)-plane. θ 1 ∈ [0, 2π] ...