PERFORMANCE ANALYSIS OF PLANAR CABLE-BASED PARALLEL MANIPULATORS

In the last two decades, many research works have been published on cable-based systems, reflecting the considerable interest of the scientific community in this area. Cables are used both in serial structures, to remotely actuate rigid links, and in parallel structures, to directly control the motion of a mobile platform or end-effector The latter subclass is particularly appealing, thanks to ease of design, high payload-to-weight ratio, potentially high dynamic performances and wide workspace. Such devices have also been effectively employed in haptics, since the use of light-weight elements allows to develop structures with low mechanical impedance. Unilateral actuation represents a major issue in the study of cable-based devices, often forcing to adopt specially formulated design tools. This paper presents a set of performance indices, some of which are introduced here for the first time, that can be used for the optimization of the design and for the analysis of cable-based devices. To prove the effectiveness of these tools, a comparison of the kinematic and dynamic performances of three different designs of planar cable-based parallel manipulators is presented.