Pneumatic Actuator Force Control with State-Observer Pressure Estimation
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Solution Overview
Problem
Existing pneumatic actuating devices, such as gripping devices, face challenges in effectively controlling the force applied, as it is dependent on air pressure in working chambers, making closed-loop control systems difficult to implement accurately.
Innovation Solution
A control method using a dynamic model of the actuating system and an optimization algorithm to calculate optimized control signals for pressure regulators, with a state observer estimating pressures and derivatives in real-time, ensuring stable and precise force control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a pneumatic actuating device is used to generate high forces, then the force output is improved, but the control precision of the force is deteriorated
Solution Approach 1:
The patent implements a closed-loop feedback control system that continuously monitors the actual force applied by the pneumatic actuating device and compares it with the desired force. Based on the error signal, the controller adjusts the control parameters of the pressure regulators to minimize the difference between actual and desired force, thereby achieving precise force control despite the inherent variability of pneumatic systems
Solution Approach 2:
The patent dynamically changes the control parameters (such as pressure setpoints and regulator gains) based on the operating conditions and error signals. By continuously adjusting these parameters through the feedback loop, the system adapts to maintain high control precision across varying force levels and operating conditions
2Measurement precision
If a closed-loop control system is implemented for force control, then the control precision is improved, but the device complexity is deteriorated
Solution Approach 1:
The controller is designed to perform multiple functions: it monitors force sensor data, calculates error signals, adjusts pressure regulator setpoints, and manages the overall control logic. By consolidating these functions into a single multi-functional control unit, the patent reduces the need for separate dedicated components for each control task, thereby limiting the increase in device complexity
Solution Approach 2:
The patent introduces a force sensor as an intermediary element that provides feedback information about the actual force applied. This intermediary component enables the closed-loop control mechanism by bridging the gap between the actuating device and the controller, allowing precise force regulation without requiring direct mechanical feedback mechanisms that would increase complexity
3Measurement precision
If pressure regulators are used to control working chamber pressures, then the force control is improved, but the energy consumption is deteriorated
Solution Approach 1:
The control system implements periodic adjustments to the pressure regulator setpoints based on the error signal and operating conditions. Rather than maintaining continuous high-pressure states, the system periodically modulates the pressure levels to achieve the desired force, allowing energy recovery and reduction during cyclic operations
Solution Approach 2:
The patent employs dynamic pressure control where the pressure regulator setpoints are continuously adjusted based on real-time feedback from the force sensor. This dynamic approach allows the system to maintain precise force control while minimizing energy consumption by applying pressure only when and where needed, rather than maintaining constant high pressure states
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
This method achieves precise control of forces with low error, minimizes energy consumption, and effectively manages complex dynamics and pressure limitations, allowing for independent control of working chamber pressures to open or close the device.
Implementation Method 1
The actuating device (10) comprises a first working chamber (14) and a second working chamber (16) which can be supplied with pressurized air in order to control the movement of the actuating member (12) with a given actuation force that is dependent on the pressures in the working chambers
Data Source
AI summary
A method is for controlling an actuation force exerted by an actuating device having a first working chamber and a second working chamber supplied with pressurized air from a source of pressurized air by a first pressure regulator and a second pressure regulator. The method includes calculating, by an optimization algorithm based on a dynamic model of the actuating device and of the first and second pressure regulators, desired values for control signals for the first and second pressure regulators to generate an actuation force equal to a desired value for the actuation force. An estimated value for the actuation force, estimated values for pressures inside the first and second working chambers and for first derivatives of the pressures, are determined by a state observer based on a measured value for the actuation force and on measured values for the pressures in the first and second working chambers.