Rotary Parallel-Link Motion Unit for Large Workspace Precision
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Solution Overview
Problem
Existing operation devices face limitations in achieving a large zone of operation, high speed, and precise intricate movements due to restricted link angles, poor rigidity, and increased device size, while also struggling with inefficient handling of workpiece orientation and cabling management.
Innovation Solution
A combination of a rotation unit and a linear motion unit, incorporating a link actuation apparatus with attitude control actuators and a rotation actuator, allows for a larger operational zone by offsetting the central axis of the link hub and rotation actuator, enabling high-speed, precise, and intricate operations, and simplifying cabling through a cable carrier and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the lengths of the links are extended to achieve a larger zone of operation, then the zone of operation is improved, but the overall size of the device increases
Solution Approach 1:
The link actuation apparatus is nested within the rotation unit, which is mounted on the linear motion unit. The parallel link mechanism is integrated into the rotation unit structure, allowing the distal end side-link hub to operate in a large zone while the overall device remains compact through hierarchical nesting of functional components
Solution Approach 2:
The invention adds rotational freedom by mounting the link actuation apparatus on a rotation unit that can rotate about a vertical axis. This transforms the operation from a two-dimensional plane to a three-dimensional spherical workspace, achieving a large zone of operation without extending link lengths in a single direction
2Area of stationary object
If the link mechanism is designed for a large zone of operation, then the zone of operation is improved, but the rigidity of the link mechanism deteriorates
Solution Approach 1:
The invention uses active control through actuators (motor M1 for link angle control and motor M2 for rotation angle control) to maintain system stability. The control unit dynamically adjusts the link angles and rotation angle to achieve precise positioning while maintaining rigidity through controlled counterbalancing forces
Solution Approach 2:
The invention changes the operational parameters by introducing a rotation angle in addition to link angles. This allows the system to achieve a large zone of operation by varying the rotation angle about the vertical axis while maintaining optimal link angles for rigidity, effectively decoupling the requirements for range of motion and structural stiffness
3Area of stationary object
If the link mechanism is designed for a large zone of operation, then the zone of operation is improved, but the weight that can be carried deteriorates
Solution Approach 1:
The active control system with motors M1 and M2 provides dynamic force compensation that allows the mechanism to maintain rigidity and carrying capacity across its entire workspace. The control unit calculates and applies appropriate counterbalancing forces based on the current position and load, enabling the system to carry heavier tools throughout the large zone of operation
4Ease of operation
If a rotation mechanism with substantial movement is used to vary tip end attitude, then the attitude control is improved, but the operation speed deteriorates
Solution Approach 1:
The invention segments the attitude control into two independent rotational movements: rotation about the vertical axis (controlled by motor M2) and rotation about the horizontal axis (controlled by motor M1). This segmentation allows each motor to operate within an optimized range of motion, achieving both precise attitude control and high operation speed without the trade-off present in single-axis mechanisms
Data Source
AI summary
An operation device including a combination of a rotation unit and a linear motion unit. The rotation unit includes a link actuation apparatus and a rotation actuator. The link actuation apparatus includes a proximal end side-link hub, and a distal end side-link hub coupled thereto through three or more link mechanisms so as to enable a varying attitude relative thereto. The link actuation apparatus is mounted to an output shaft of the rotation actuator such that a central axis of the proximal end side-link hub forms an angle relative to an axis of rotation of the rotation actuator. The linear motion unit includes a linear actuator serving as an output portion thereof, and the rotation unit is mounted to this linear actuator.