This article is based on the observation that spatial parallel platform mechanisms of a certain architecture that use five-bar-linkages as legs can be statically balanced. Static balancing is a very important property for many applications, since it means that the mechanism is statically stable for any configuration, i.e. zero actuator forces are required whenever the manipulator is at rest. Static balancing is achieved by attaching springs to the two bottom links of each five-bar-linkage.
In another article also presented at this conference (MECH-5964) it is shown that a certain class of mechanisms can be statically balanced. This article follows up with a kinematic study of that mechanism class. The following results are obtained in this article: (1) the inverse kinematics are derived in closed form for the mechanism class, (2) the Jacobian matrix is derived in a general form for the mechanism class, (3) a sample mechanism is selected for which the forward kinematics problem is equivalent to the forward kinematics of the MSSM mechanism, (4) a method for the determination of singularity-free half-cylinders is presented for the sample mechanism, and (5) its workspace is briefly discussed.