PT
P.T. Tempel
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Cable Driven Parallel Robots, or CDPRs, might provide art historians and curators with an improved automated way of scanning 3D art objects. This application requires CDPRs to rotate around a 3D object with large panning and tilting, while avoiding collisions. While no designs exist for this purpose, this article investigates and proposes new cable robot geometries. First, we built a workspace model to quantify the performance of a design. A brainstorm and the ACCREx method then provided us with over 100 promising robot architectures. Their subsequent testing with the workspace model revealed the nine most promising architectures. Lastly, a geometry optimization resulted in the most favourable CDPR geometries. It appeared that mainly cable force limits, cable-statue and platform-statue collision are limiting the workspace of the CDPRs. In the end, the best enclosing and non-enclosing design are capable of reaching 29% and 16% respectively of the required 180 degrees workspace around the statue. Without extra panning and tilting these percentages are 79% and 66% respectively. Both designs show to which extend a statue can be scanned by a CDPR from one configuration.
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Cable Driven Parallel Robots, or CDPRs, might provide art historians and curators with an improved automated way of scanning 3D art objects. This application requires CDPRs to rotate around a 3D object with large panning and tilting, while avoiding collisions. While no designs exist for this purpose, this article investigates and proposes new cable robot geometries. First, we built a workspace model to quantify the performance of a design. A brainstorm and the ACCREx method then provided us with over 100 promising robot architectures. Their subsequent testing with the workspace model revealed the nine most promising architectures. Lastly, a geometry optimization resulted in the most favourable CDPR geometries. It appeared that mainly cable force limits, cable-statue and platform-statue collision are limiting the workspace of the CDPRs. In the end, the best enclosing and non-enclosing design are capable of reaching 29% and 16% respectively of the required 180 degrees workspace around the statue. Without extra panning and tilting these percentages are 79% and 66% respectively. Both designs show to which extend a statue can be scanned by a CDPR from one configuration.
Master thesis
(2021)
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P.I. van der Stigchel, V. van der Wijk, P.T. Tempel, J.L. Herder, M.W.E.M. Alfeld
In cable driven parallel robots (CDPRs), the end effector or moving platform is actuated by multiple cables in parallel that are wound on winches, which are located on a frame. Compared to classical parallel robots, such as the Delta robot, CDPRs have a lower inertia due to low cable masses. Therefore, they can perform high speed motions with a low power consumption. Additionally, the workspace of a CDPR is easily scalable as the cable lengths are hardly limited. Consequently, the CDPRs can potentially improve efficiency and reduce the cost of high speed pick and place operations, which are now often carried out by Delta robots. However, CDPRs have not yet been applied in the high speed pick and place industry. One of the reasons that CDPRs are not yet attractive for this industry is their limited orientation range. In pick and place applications it is often required to not only translate a product, but also reorient it about one axis for proper packaging. This motion is also known as a Schönflies motion. For full product reorientation, a rotation of 180 degrees is required, which can only be achieved with an additional axis on the moving platform. Several solutions for large rotations of CDPRs exist in literature, but none of them are designed, compared, modelled or tested for dynamic purposes. Therefore, this thesis proposes three concept designs of CDPRs that can perform a Schönflies motion, including a rotation of 180 degrees. These concept designs are compared with each other and on a state of the art Delta robot, based on their dynamic workspace. The dynamic workspace volume of each concept is optimized for their geometric parameters by the particle swarm algorithm, which showed that the concept that uses a cable loop to perform the rotation has the largest workspace for the smallest cable forces. Additionally, a prototype of this concept has been evaluated on a typical pick and place motion, which shows the feasibility of this concept. Nonetheless, stiffness should improve to reach the state of the art repeatability in future designs.
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In cable driven parallel robots (CDPRs), the end effector or moving platform is actuated by multiple cables in parallel that are wound on winches, which are located on a frame. Compared to classical parallel robots, such as the Delta robot, CDPRs have a lower inertia due to low cable masses. Therefore, they can perform high speed motions with a low power consumption. Additionally, the workspace of a CDPR is easily scalable as the cable lengths are hardly limited. Consequently, the CDPRs can potentially improve efficiency and reduce the cost of high speed pick and place operations, which are now often carried out by Delta robots. However, CDPRs have not yet been applied in the high speed pick and place industry. One of the reasons that CDPRs are not yet attractive for this industry is their limited orientation range. In pick and place applications it is often required to not only translate a product, but also reorient it about one axis for proper packaging. This motion is also known as a Schönflies motion. For full product reorientation, a rotation of 180 degrees is required, which can only be achieved with an additional axis on the moving platform. Several solutions for large rotations of CDPRs exist in literature, but none of them are designed, compared, modelled or tested for dynamic purposes. Therefore, this thesis proposes three concept designs of CDPRs that can perform a Schönflies motion, including a rotation of 180 degrees. These concept designs are compared with each other and on a state of the art Delta robot, based on their dynamic workspace. The dynamic workspace volume of each concept is optimized for their geometric parameters by the particle swarm algorithm, which showed that the concept that uses a cable loop to perform the rotation has the largest workspace for the smallest cable forces. Additionally, a prototype of this concept has been evaluated on a typical pick and place motion, which shows the feasibility of this concept. Nonetheless, stiffness should improve to reach the state of the art repeatability in future designs.