Table 2. D-H parameters of manipulators.

Joint i	θi	αi	di	ai
0(R)	0	0	0	0
1(R)	θ1	90	422.2247	-51.8427
2(R)	θ2	0	0	803.6246
3(P*)	θ3	90	0	59.5
4(P)	0	0	412	0

where,
θ_i: the angle between x_{i − 1} and x_i measured about z_i, variable.
α_i: the angle between z_i and z_{i + 1} measured about x_i, constant.
d_i: the distance from x_{i − 1} to x_i measured along z_i, constant.
a_i : the distance from z_i and z_{i + 1} measured along x_i, constant.
*: fixed prismatic joint due to linkage.