ICubFowardKinematics left

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This page describes how to construct the matrix T_RoLa whose definition is given in ICubForwardKinematics. The matrix is constructed in two steps i.e. T_RoLa = T_Ro0 * T_0n. The first matrix T_Ro0 describes the rigid roto-translation from the root reference frame to points in the 0th reference frame as defined by the Denavit-Hartenberg convention. In this case T_Ro0 is just a rigid rotation which aligns the z-axis with the first joint of the waist. The second matrix T_0n corresponds to the Denavit-Hartenberg description of the forward kinematic, i.e. the roto-translation from the 0th reference frame to the nth reference frame being n the number of degrees of freedom. The forward kinematic in this case includes the waist and the left arm forward kinematics.

The matrix T_0n is itself the composition of n matrices as defined by the DH convention: T_0n = T_01 T_12 ... T_(n-1)n. Here is the updated matlab code for computing the forward kinematics with the Denavit Hartenberg notation Media: ICubFwdKinNew.zip.

The hand reference frame is located in the palm as shown in the CAD figure. The x axis is in red. The y axis is in green. The z axis is in blue.


DHnotation Left.jpg LeftHandCADRefFrame.jpg

Here is the matrix T_Ro0:

0 -1 0 0
0 0 -1 0
1 0 0 0
0 0 0 1


Here is the table of the actual DH parameters for left arm v1.

Link i / H – D Ai (mm) d_i (mm) alpha_i (rad) theta_i (deg)
i = 0 32 0 pi/2 -22 -> 84
i = 1 0 -5.5 pi/2 -90 + (-39 -> 39)
i = 2 23.3647 -143.3 -pi/2 105 + (-59 -> 59)
i = 3 0 107.74 -pi/2 90 + (5 -> -95)
i = 4 0 0 pi/2 -90 + (0 -> 160.8)
i = 5 15 152.28 -pi/2 75 + (-37 -> 100)
i = 6 -15 0 pi/2 5.5 -> 106
i = 7 0 137.3 pi/2 -90 + (-50 -> 50)
i = 8 0 0 pi/2 90 + (10 -> -65)
i = 9 62.5 -16 0 (-25 -> 25)


Here is the table of the actual DH parameters for left arm v1.7.

Link i / H – D Ai (mm) d_i (mm) alpha_i (rad) theta_i (deg)
i = 0 32 0 pi/2 -22 -> 84
i = 1 0 -5.5 pi/2 -90 + (-39 -> 39)
i = 2 23.3647 -143.3 -pi/2 105 + (-59 -> 59)
i = 3 0 107.74 -pi/2 90 + (5 -> -95)
i = 4 0 0 pi/2 -90 + (0 -> 160.8)
i = 5 15 152.28 -pi/2 75 + (-37 -> 100)
i = 6 -15 0 pi/2 5.5 -> 106
i = 7 0 141.3 pi/2 -90 + (-50 -> 50)
i = 8 0 0 pi/2 90 + (10 -> -65)
i = 9 62.5 -16 0 (-25 -> 25)


Here is the table of the actual DH parameters for left arm v2.

Link i / H – D Ai (mm) d_i (mm) alpha_i (rad) theta_i (deg)
i = 0 32 0 pi/2 -22 -> 84
i = 1 0 -5.5 pi/2 -90 + (-39 -> 39)
i = 2 23.3647 -143.3 -pi/2 105 + (-59 -> 59)
i = 3 0 107.74 -pi/2 90 + (5 -> -95)
i = 4 0 0 pi/2 -90 + (0 -> 160.8)
i = 5 15 152.28 -pi/2 75 + (-37 -> 100)
i = 6 -15 0 pi/2 5.5 -> 106
i = 7 0 141.3 pi/2 -90 + (-50 -> 50)
i = 8 0 0 pi/2 90 + (10 -> -65)
i = 9 62.5 -25.98 0 (-25 -> 25)