Hybrid Piston Actuator for Compact High-Output Force Control
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Solution Overview
Problem
Conventional electromagnetic actuators face challenges in achieving high output while maintaining compactness, and hybrid actuators often suffer from impaired responsiveness, robustness, and limited range of motion due to mechanical linkages and gears.
Innovation Solution
The development of a compact, high-output actuator device that integrates fluid pressure and electromagnetic force for force control, utilizing a fluid-tight housing with a movable piston and a magnetic member for relative movement, and a control unit to coordinate fluid pressure and electromagnetic excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electromagnetic actuators are made larger to achieve high output, then power increases, but device size increases
Solution Approach 1:
The patent combines electromagnetic actuation and pneumatic actuation into a single hybrid actuator device. The electromagnetic motor drives a piston that moves within a cylinder, while pneumatic pressure acts on the same piston to assist the driving force. This merging of two actuation mechanisms allows the device to achieve high output power while maintaining a compact size, as the pneumatic component provides additional force without requiring a larger electromagnetic motor.
2Power
If mechanical linkages and gears are used in hybrid actuators, then force transmission is achieved, but responsiveness and robustness are impaired
Solution Approach 1:
The patent replaces traditional mechanical linkages and gears with a direct-drive pneumatic-mechanical system. The piston rod directly transmits force from the piston to the output, eliminating intermediate mechanical components. This substitution maintains force transmission capability while significantly improving responsiveness by removing mechanical delays and reducing the number of moving parts that could fail.
3Measurement precision
If electromagnetic actuators are used for force control, then positioning accuracy is achieved, but heat generation increases
Solution Approach 1:
The patent introduces pneumatic pressure as an intermediary to assist the electromagnetic motor in generating driving force. The pneumatic system provides additional force that supplements the electromagnetic actuation, allowing the electromagnetic motor to operate at lower power levels while maintaining the same output force. This reduces heat generation from the electromagnetic coil while preserving positioning accuracy through coordinated control of both actuation mechanisms.
4Reliability
If air spring is used in electromagnetic actuator, then shock alleviation is achieved, but range of motion is limited
Solution Approach 1:
The patent merges the air spring shock alleviation function with the pneumatic actuation system into a unified design. The same pneumatic pressure supply that provides driving force also serves as the cushioning medium at the stroke ends. This eliminates the need for a separate air spring component and its associated space, thereby maintaining shock alleviation capabilities while maximizing the usable range of motion within the actuator.
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 actuator device achieves compactness, high output, and responsive force control, enabling efficient power assistance for applications like exoskeleton robots, while reducing heat generation and maintaining back-drivability.
Implementation Method 1
a first magnetic member provided outside of the fluid-tight housing along a moving path of the movable element; wherein the movable element has a second magnetic member and is moved relative to the first magnetic member by excitation of the first or second magnetic member
Implementation Method 2
a movable element contained in the fluid-tight housing and slidable in accordance with the fluid pressure in the fluid-tight housing; fluid pressure supplying means for supplying the fluid pressure to each of the first and second chambers
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
[Object] To provide a compact, high-output actuator device allowing force control. [Solution] An actuator device 1000 includes an electromagnetic coil member 110 provided over a prescribed width on an outer circumference of a cylinder 100, and a movable element 200 slidable as a piston in the cylinder 100. The movable element 200 has a magnetic member 202, and is moved relatively by excitation of the electromagnetic coil member 110. Fluid is supplied to first and second chambers 106a and 106b such that when the movable element 200 is to be moved relatively, the movable element 200 is driven in the same direction.