889 research outputs found
On the optimal design of parallel robots taking into account their deformations and natural frequencies
This paper discusses the utility of using simple stiffness and vibrations
models, based on the Jacobian matrix of a manipulator and only the rigidity of
the actuators, whenever its geometry is optimised. In many works, these
simplified models are used to propose optimal design of robots. However, the
elasticity of the drive system is often negligible in comparison with the
elasticity of the elements, especially in applications where high dynamic
performances are needed. Therefore, the use of such a simplified model may lead
to the creation of robots with long legs, which will be submitted to large
bending and twisting deformations. This paper presents an example of
manipulator for which it is preferable to use a complete stiffness or vibration
model to obtain the most suitable design and shows that the use of simplified
models can lead to mechanisms with poorer rigidity
Appropriate Design of Parallel Manipulators
International audienceAlthough parallel structures have found a niche market in many applications such as machine tools, telescope positioning or food packaging, they are not as successful as expected. The main reason of this relative lack of success is that the study and hardware of parallel structures have clearly not reached the same level of completeness than the one of serial structures. Among the main issues that have to be addressed, the design problem is crucial. Indeed, the performances that can be expected from a parallel robot are heavily dependent upon the choice of the mechanical structure and even more from its dimensioning. In this chapter, we show that classical design methodologies are not appropriate for such closed-loop mechanism and examine what alternatives are possible
Design and analysis of a parallel mechanism for kinematically redundant hybrid planar laser cutting machine
Conventional planar laser cutting machines cannot achieve high accelerations, because the required precision values cannot be achieved due to the high inertial loads. Machines configured as kinematically redundant mechanisms are able to reach 5-6 g acceleration levels since they include a parallel mechanism with a smaller workspace which is exposed to smaller inertial loads. The study presented in this paper focuses on the design of a parallel planar mechanism to be integrated to the main axes of conventional planar laser cutting machines to achieve higher accelerations of the laser head up to 6 g. Parallel mechanism’s conceptual design and dynamic balancing studies are provided along with the joint clearance effect on precision due to having more joint structures.Republic of Turkey Ministry of Science, Industry and Technology & Coşkunöz Metal Form (Project code: 01668.STZ.2012-2
Optimal dimensional synthesis of force feedback lower arm exoskeletons
This paper presents multi-criteria design optimization of parallel mechanism based force feedback exoskeletons for human forearm and wrist. The optimized devices are aimed to be employed as a high fidelity haptic interfaces. Multiple design objectives are discussed and classified for the devices and the optimization problem to study the trade-offs between these criteria is formulated. Dimensional syntheses are performed for optimal global kinematic and dynamic performance, utilizing a Pareto front based framework, for two spherical parallel mechanisms that satisfy the ergonomic necessities of a human forearm and wrist. Two optimized mechanisms are compared and discussed in the light of multiple design criteria. Finally, kinematic structure and dimensions of an optimal exoskeleton are decided
A New 3-DoF Planar Parallel Manipulator with Unlimited Rotation Capability
International audienceMost of three-degree-of-freedom (3-DoF) planar parallel manipulators encountered today have a common disadvantage that is their low rotational capability. However, for many industrial applications, by example in automated assembly systems, cutting machines, simulators, or micro-motion manipulators, a high rotation capability is needed. To overcome such a difficulty, this paper focuses its attention on the proposal of a new 3-DoF planar parallel manipulator capable of high rotational capability. Firstly, structure and mobility of the suggested manipulator are discussed. Then the forward and inverse kinematic problems are analyzed, as well as it is disclosed its singular configurations. The shaking force and shaking moment balancing are also considered. The proposed design concept is illustrated by a driven demonstrator which is a first model of the suggested manipulator
- …