Compact Linear Drive Using Stick-Slip Friction
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Solution Overview
Problem
Existing linear drives for precision positioning are limited by large size due to the need for extensive clearance between guide elements, which hinders miniaturization and precision, and are prone to tilting and positional errors.
Innovation Solution
A compact linear drive design utilizing two guide elements with static friction to achieve precise displacement through a stick-slip effect, where both guide elements are engaged with the movement element to reduce tilting risks and allow for precise positioning, using actuators to drive the guide elements synchronously or asynchronously along parallel or non-parallel trajectories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional linear guide elements with large clearance are used, then the movement element can be displaced along the guide elements, but the device occupies large space and precision positioning is limited
Solution Approach 1:
The patent changes the friction parameter between guide elements and movement element from low friction (conventional linear bearings) to high static friction (stick-slip effect). By using materials with high friction coefficients and optimizing contact pressure, the clearance can be dramatically reduced while maintaining positioning precision through the stick-slip displacement mechanism
Solution Approach 2:
The patent employs ultrasonic vibration at the interface between guide elements and movement element to enable controlled stick-slip displacement. The vibration frequency and amplitude are optimized to create alternating sticking and slipping phases, allowing precise positioning with minimal clearance and eliminating the need for large clearance conventional bearings
2Device complexity
If only one guide element is used to generate stick-slip effect, then the device structure is simplified, but the movement element is prone to tilting and positional errors
Solution Approach 1:
The patent merges the functions of multiple guide elements into a unified stick-slip drive system where both guide elements actively participate in generating the stick-slip effect simultaneously. This combination provides mutual constraint and support, preventing tilting of the movement element while maintaining relatively simple individual guide element structures
Solution Approach 2:
The patent employs asymmetric arrangement of the two guide elements relative to the movement element, with different orientations and contact points. This asymmetric configuration creates complementary constraint forces that effectively prevent tilting in multiple directions, improving positioning stability without requiring overly complex symmetric structures
3Ease of operation
If extensive clearance is provided between movement element and guide elements, then the movement element can be displaced freely, but the positioning precision and miniaturization are hindered
Solution Approach 1:
The patent fundamentally changes the friction parameter from low to high, enabling the movement element to be firmly held during sticking phases while allowing controlled displacement during slipping phases. This parameter change allows minimal clearance to provide both firm holding and movement freedom, achieving high positioning accuracy without extensive clearance
Solution Approach 2:
The patent employs periodic ultrasonic vibration to create alternating sticking and slipping phases. During sticking phases, the movement element is firmly held with minimal clearance for high positioning accuracy; during slipping phases, controlled displacement occurs. This periodic action provides both movement freedom and positioning precision with minimal clearance
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 solution enables a compact, precise, and stable displacement of the movement element with reduced tilting risks and positional errors, allowing for high-precision positioning and potentially eliminating the need for expensive linear bearings.
Implementation Method 1
The actuator unit can comprise one or more actuators, in particular piezo actuators, which serve as electromechanical converters and transmit an electric alternating voltage into an oscillating movement of the piezo actuator.
Implementation Method 2
the movement element can be displaced along both guide elements as a result of a stick-slip effect by means of a movement generated by the actuator unit
Implementation Method 3
the movement element can be brought into engagement with each of the two guide elements by means of static friction in order to be displaced along the two guide elements as a result of the stick-slip effect
Data Source
AI summary
The present disclosure relates to a linear drive, including: an actuator unit with at least one actuator; two guide elements and a movement element, wherein the movement element is displaceable along both guide elements by a movement generated by the actuator unit as a result of a stick-slip effect. In order to allow a more accurate displacement of the movement element in a compact design of the linear drive, the movement element can be brought into engagement with each of the two guide elements by static friction in order to be displaced along the two guide elements as a result of the stick-slip effect.