Fluidic Actuator Control Switching for Low-Energy Position Holding
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Solution Overview
Problem
Cascaded closed-loop control in fluidic actuators requires high energy due to the need for fast subordinate control loops, exceeding the energy budget of 2-wire positioners, especially when combined with position control.
Innovation Solution
Activating a pressure controller mode when the actuator member is within a predetermined position target range, allowing for closed-loop pressure control with a lower temporal resolution and reducing energy consumption, while maintaining robustness by compensating minor disturbances without moving the actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cascaded closed-loop control is implemented with fast subordinate control loop, then control robustness is improved, but energy consumption increases significantly
Solution Approach 1:
The control device dynamically switches between position controller mode and pressure controller mode based on whether the actuator member is within the position target range. When within range, pressure controller mode is activated with reduced temporal resolution, reducing energy consumption while maintaining robustness against minor disturbances. This dynamic adaptation resolves the contradiction by adjusting control intensity to actual system needs.
Solution Approach 2:
The invention changes the temporal resolution parameter of the control loop based on operating conditions. When the actuator is within the target range, the subordinate control loop operates at lower temporal resolution, reducing energy consumption. When outside the range, full temporal resolution is restored to ensure fast response. This parameter adaptation allows maintaining robustness while reducing energy usage during stable operation.
2Manufacturing precision
If pressure sensors are read out with short cycle time for cascaded control, then control quality is improved, but energy budget is exceeded
Solution Approach 1:
The pressure sensor reading cycle time is periodically adjusted based on the actuator's position relative to the target range. When within range, readings occur at longer intervals with lower temporal resolution. When outside range, reading frequency increases to ensure precise control. This periodic adaptation maintains control quality when needed while reducing energy consumption during stable operation.
Solution Approach 2:
The control system dynamically adjusts the reading cycle time of pressure sensors based on operational requirements. The system transitions between two operational states: high-frequency reading when correction is needed, and low-frequency reading when the system is stable. This dynamic adjustment resolves the contradiction between control quality and energy budget.
3Measurement precision
If position controller mode is continuously active, then position accuracy is maintained, but energy consumption increases
Solution Approach 1:
The invention extracts the pressure control function from the continuous position control loop and makes it independent when the actuator is within the target range. Instead of continuously executing the full cascaded position control, the system activates only the pressure controller mode with reduced temporal resolution, taking out the essential pressure maintenance function while eliminating unnecessary energy-consuming position control operations.
Solution Approach 2:
When the actuator is within the position target range, the system applies partial action by activating only the pressure control component with reduced temporal resolution, rather than full position control. This partial action is sufficient to maintain position accuracy through pressure stabilization, reducing energy consumption while preserving necessary control functionality.
Data Source
AI summary
A control device for providing a position controller mode for closed-loop position control of an actuator member of a fluidic actuator which can be driven by a pressurized fluid, wherein the control device is configured to activate a pressure controller mode in response to the actuator member being located in a position target range given by a target position value of the closed-loop position control, and, in the pressure controller mode, to carry out a closed-loop pressure control of the pressurized fluid on the basis of a target pressure value.