Linear Actuator with Load Cell for Force Feedback
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Solution Overview
Problem
Miniature linear actuators lack a feedback mechanism for force calibration, leading to instability in force generation due to temperature effects, which can result in over-compression and chipping of fragile components during picking and placing processes, affecting positional accuracy and product yield.
Innovation Solution
A linear actuator design incorporating a load cell with strain gauges to measure and calibrate forces, connected to both a linear motor and a rotary motor, which converts force into an electrical signal for feedback control, minimizing size and offsetting components for stable operation, and featuring a limitation part to prevent excessive deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional linear actuators operate without a feedback mechanism, then the device complexity is reduced, but the force generation stability deteriorates due to temperature effects causing thermal expansion and magnetic field instability
Solution Approach 1:
The patent implements a feedback mechanism using a load cell that measures the actual force generated by the linear actuator and feeds this information back to the driver. The driver then adjusts the drive signal to compensate for temperature-induced variations, maintaining stable force generation despite thermal effects during operation
Solution Approach 2:
The system dynamically adjusts operational parameters based on temperature changes and measured force deviations. The driver modifies drive signals in real-time to compensate for thermal expansion and magnetic field instability, maintaining consistent force output across varying temperature conditions
2Reliability
If a load cell is added to provide force feedback, then the force generation stability is improved, but the device complexity increases
Solution Approach 1:
The load cell is integrated into the existing structure of the linear actuator, with the movable magnetic backplane and rotary motor connected to opposite sides of the load cell. This merging approach allows force measurement functionality to be incorporated without requiring a completely separate measurement system
Solution Approach 2:
The load cell serves multiple functions: it measures force for feedback control, calibrates the force generation, and provides data for both positional accuracy maintenance and force reproducibility. This multi-functionality reduces the need for separate dedicated components
3Volume of moving object
If the linear actuator is designed with a slim arrangement, then the size is reduced, but the stability deteriorates due to offset between supporting and center of gravity
Solution Approach 1:
The patent deliberately creates an asymmetric arrangement where the supporting point and center of gravity are offset in the direction of picking and placing components. This asymmetric design, combined with the slim profile, is optimized to minimize shaking during reciprocating motion while maintaining a compact form factor
4Productivity
If the linear actuator operates at high speed and high precision, then the productivity is improved, but the manufacturing precision deteriorates due to over-compression and chipping of fragile components
Solution Approach 1:
The load cell provides real-time force measurement feedback during the picking and placing process. The driver uses this feedback to dynamically adjust the applied force, ensuring that fragile components are handled with appropriate force levels even during high-speed operation, preventing over-compression and chipping
Solution Approach 2:
The system dynamically adjusts force application based on real-time feedback from the load cell. During reciprocating motion, the drive signal is continuously modified to maintain force within safe limits for fragile components, enabling high-speed operation without compromising component integrity
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 ensures precise positional accuracy and prevents over-compression, maintaining reproducibility of force and stability across temperature variations, while preventing irreversible deformation of the load cell, thus enhancing the reliability of the picking and placing process.
Implementation Method 1
the load cell includes a spring element, a plurality of strain gauges and a limitation part... When the force is exerted on the load cell, the spring element is deformed... As the spring element deforms, the strain gauges disposed on the spring element are also deformed, and the deformation of strain gauges is converted into an electrical signal
Implementation Method 2
The linear motor is disposed on the base and includes a fixed coil module and a movable magnetic backplane... The movable magnetic backplane is configured to slide relative to the fixed coil module along the first direction
Implementation Method 3
The rotary motor is rotated around a central axis in parallel with the first direction... subjected to a force applied thereto by the rotary motor and parallel to the first direction
Data Source
AI summary
The disclosure relates to a linear actuator including a base, a linear motor, a load cell and a rotary motor. The linear motor is disposed on the base and includes a fixed coil module and a movable magnetic backplane. The fixed coil module is fixed on the base, and the movable magnetic backplane is configured to slide relative to the fixed coil module along a first direction. The rotary motor is rotated around a central axis in parallel with the first direction. The load cell has two opposite sides parallel to the first direction, respectively. The movable magnetic backplane of the linear motor and the rotary motor are connected to the two opposite sides of the load cell, respectively. The load cell is subjected to a force applied thereto by the rotary motor and parallel to the first direction, and configured to convert the force into an electrical signal.