Chap 11 – Case Studies

11.6 Space Station Remote Manipulator System (SSRMS)

7 axis manipulator, 7 d.o.f. (redundant) 1st & 2nd axes intersect 6th & 7th axes intersect 3rd, 4th, & 5th axes are parallel

The manipulator is classified as being redundant since only six joint axes are necessary to position and orient the end effector arbitrarily in space. The reverse kinematic position analysis will proceed, however, by having the user specify one of the joint angle parameters in addition to specifying the desired position and orientation of the end effector.

In the present analysis, the user must specify 2 in addition to the desired end effector position and orientation. This strategy offers a distinct advantage in that the parameter 2 has a physical meaning for the operator. This angle governs the orientation of the longest links of the manipulate or (a34 and a45) with respect to the XY plane through the base of the robot. The prior specification of 2 will enable the user to take better advantage of the redundancy of the system by being able to position the longest links of the manipulator to move over or around obstacles in the workspace.

Make a free choice for the offset S7 and establish a direction for the vector a78 in the last link. (Establish the 7th coordinate system.)

Obtain the coordinates of the origin of the 7th coordinate system with respect to ground. Close the loop. Obtain a81, S8, S1, 8, 81, 1.

11.6.1 Development of an Equivalent 6 Degree of Freedom Manipulator obtain 12’ , a12’, S1’, and S2’

special configuration if 2 equals 0 or 180, 4 axes parallel

project vector loop onto S2 (z comp. of set 14) project vector loop onto x & y axes of set 14, square and add x & y axes of set 14

11.7 Modified Flight Telerobotic Servicer (FTS) Manipulator System original FTS design modified FTS design

redundant robot assume 7 is given

redundant robot assume 7 is given

redundant robot assume 7 is given

redundant robot assume 7 is given calculate where

redundant robot assume 7 is given

redundant robot assume 7 is given 1st & 2nd axes intersect 3rd & 4th axes parallel 5th & 6th axes intersect