Redundant-Actuated Parallel Mechanism for Singularity-Free Rotation
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Solution Overview
Problem
Existing parallel mechanisms have limited rotational range of motion, especially in flight simulation applications, due to kinematic singularities and the inability to scale rotational range with translational range.
Innovation Solution
A spatial parallel mechanism with kinematically redundant actuation, featuring passive distal and proximal joints, and actuated joints and links, allowing for increased rotational workspace by avoiding singularities through proper design and trajectory planning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the mechanism is scaled up to increase translational range of motion, then the translational workspace is improved, but the rotational range of motion remains limited by kinematic singularities
Solution Approach 1:
The patent changes the kinematic parameters of the mechanism by introducing kinematically redundant actuation. Instead of simply scaling up the mechanism dimensions, it modifies the actuation system to include redundant degrees of freedom, allowing the mechanism to avoid singular configurations and achieve larger rotational workspaces without proportionally increasing the size of all components.
Solution Approach 2:
The patent introduces dynamic control strategies that actively manage the mechanism's configuration to avoid singularities. By using redundant actuators, the system can dynamically adjust its kinematic state to maintain optimal performance across a wider range of motions, particularly improving rotational capabilities without being constrained by fixed geometric limitations.
2Device complexity
If passive distal and proximal joints are used to simplify the mechanism, then the device complexity is reduced, but the ability to achieve large rotational workspace is limited
Solution Approach 1:
The patent makes the actuated joints serve multiple functions: they not only control the primary motion of the mechanism but also actively participate in avoiding singularities and expanding the rotational workspace. The redundant actuators provide both motion control and singularity avoidance capabilities, making the actuation system universally functional rather than requiring separate systems for each purpose.
Solution Approach 2:
The patent employs preliminary action by using the redundant actuators to proactively position the mechanism in configurations that avoid singularities before they are encountered during operation. The extra degrees of freedom allow the system to pre-adjust its configuration to maintain optimal performance throughout the motion range.
3Ease of operation
If kinematically redundant actuation is introduced to increase rotational workspace, then the rotational range of motion is improved, but the device complexity increases
Solution Approach 1:
The patent merges the functions of singularity avoidance and workspace expansion into the existing actuation system. Rather than adding completely separate systems for these purposes, the redundant actuators are integrated into the leg structures, combining multiple functions into a unified system that manages complexity more effectively.
Data Source
AI summary
A spatial parallel mechanism comprises a platform. Three or more legs configured for extending from a base or ground to the platform, each leg has a distal link, one or more distal joint providing one rotational degree of freedom (DOF) about a distal rotational axis, the distal joint connecting a distal end of the distal link to the platform. A proximal joint provides at least two rotational DOFs at the proximal end of the distal link. Assemblies of joints and links provide DOFs to each said leg between the proximal joint and the base or ground. The distal rotational axes of the three legs are parallel to one another.