Parallel Positioner With 5-DOF Joints for Low-Complexity Precision
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Solution Overview
Problem
Hexapods, despite being a superior multi-axis positioning stage design, are cost-prohibitive due to their complex motion and speed profile requirements, which necessitate high computational power and expensive actuators, and they suffer from tolerance stack up issues.
Innovation Solution
A parallel position manipulator with a top plate, a base plate, and three to six prismatic joint actuators, each with five Degrees of Freedom, allowing independent motion of actuators to prevent binding and reduce computational complexity, while using magnetic forces and pliable polymers to maintain contact between pivot points and plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hexapod design is used for multi-axis positioning, then positioning precision is improved, but device complexity and cost increase exponentially
Solution Approach 1:
The system divides the positioning task into independent linear actuator movements along three orthogonal axes, rather than using coupled spherical joints. Each actuator controls one degree of freedom independently, segmenting the complex hexapod motion into simpler, decoupled linear motions that achieve the same positioning capability without the complexity of mutual actuator interaction
Solution Approach 2:
The invention replaces the mechanical spherical joint system of hexapods with a different mechanical approach using prismatic actuators and five-degree-of-freedom joints. This substitution eliminates the need for complex speed profile calculations and mutual actuator coordination while maintaining positioning precision, thereby reducing device complexity and computational requirements
2Measurement precision
If hexapod design is used for multi-axis positioning, then positioning precision is improved, but cost increases significantly
Solution Approach 1:
The system uses standard prismatic actuators and simple five-degree-of-freedom joints instead of expensive high-precision spherical bearings. These components are cheaper and easier to manufacture while achieving the required positioning precision through their coordinated action, significantly reducing the overall system cost compared to hexapod designs
Solution Approach 2:
The invention changes the fundamental motion parameters from spherical joint rotations to linear actuator extensions. This parameter change allows the use of simpler, less expensive actuators and joints while maintaining positioning accuracy through the mathematical relationship between linear actuator displacements and the resulting platform position
3Measurement precision
If spherical joints with tight tolerances are used to reduce slop, then positioning resolution is improved, but actuator capability requirements and computational power increase exponentially
Solution Approach 1:
The system segments the motion control into three independent linear axes, allowing each actuator to operate within a simple, well-defined range of motion. This segmentation eliminates the need for high capability actuators that would be required to control complex spherical joint rotations, while maintaining positioning resolution through precise control of linear actuator positions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The parallel position manipulator achieves precise positioning without the mechanical stack up issues of kinematic chains and the high costs of hexapods, allowing for scalable, cost-effective, and efficient multi-axis positioning with submicron precision.
Implementation Method 1
magnetic force, gravity, and/or a pliable polymer, such as silicone, may be employed to keep the up to five DOF pivot points in contact with their respective (that is, top or bottom) plate
Implementation Method 2
magnetic force, gravity, and/or a pliable polymer, such as silicone, may be employed to keep the up to five DOF pivot points in contact with their respective (that is, top or bottom) plate
Data Source
AI summary
A parallel position manipulator includes a top plate, a baseplate and a plurality of prismatic joint actuators. Each actuator includes an actuator joint having five Degrees of Freedom (DOF) at either the base plate or the top plate. When one or more of the actuators extends or contracts, the pivot points, or five DOF actuator joint, of the remaining actuators are allowed to shift in any axis other than that actuator's primary axis of motion.