Parallel Rolling Screw Actuator Control for Precise Load Distribution
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Solution Overview
Problem
Existing electromechanical force actuators face imprecision in parallel drive coordination due to mechanical construction, which affects load distribution and control precision, especially in applications requiring large actuation forces like subsea drilling and well completion.
Innovation Solution
An electrically driven actuator device with at least two parallel rolling screws, each coupled to an electric motor via a gear system, featuring a control system with encoders and contactless linear position sensors for precise coordination and position control, ensuring robust and precise actuation with anchored actuator spindles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical construction with spherical bearings and rounded end surfaces is used to couple actuation elements to rolling nuts, then the device can accommodate imprecision in parallel drive, but the control precision and load distribution deteriorate
Solution Approach 1:
The patent replaces the mechanical coupling system (spherical bearings and rounded end surfaces) with an electrical control system. Each rolling screw is equipped with a linear encoder that provides precise position feedback to a control system, which then coordinates the motors to achieve precise parallel drive. This substitution of mechanical tolerance accommodation with electronic control resolution the contradiction between mechanical adaptability and control precision.
2Adaptability or versatility
If mechanical construction with spherical bearings is used to couple actuation elements to rolling nuts, then the device can accommodate imprecision, but the load distribution between parallel screws deteriorates
Solution Approach 1:
The patent implements a feedback control system where linear encoders on each rolling screw provide real-time position feedback to a control system. The control system uses this feedback to continuously monitor and adjust the position of each rolling screw, ensuring equal load distribution between parallel screws. This active feedback mechanism replaces the passive mechanical accommodation of imprecision, achieving both adaptability and proper load distribution.
3Measurement precision
If contactless linear position sensors and encoders are added to each rolling screw, then control precision and position monitoring improve, but device complexity increases
Solution Approach 1:
The patent integrates multiple functions into the control system: the linear encoders serve both as position sensors for the rolling nuts and as synchronization references for coordinating multiple motors. The control system simultaneously performs position control, speed synchronization, and load distribution optimization. This multi-functionality reduces the need for separate systems, thereby mitigating the increase in complexity while achieving high precision.
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 provides precise control and monitoring of force and position, enabling robust and efficient operation in both directions with reduced load on well barrier components and improved damping, enhancing the reliability and performance of subsea actuation systems.
Implementation Method 1
contactless, linear position sensors... One contactless, linear position sensor is fastened in the actuator housing adjacent to each of the sensor heads and is configured to communicate information about a position of each of the sensor heads to the control system
Implementation Method 2
Each electric motor comprises a motor driver and at least one encoder which is coupled to the control system, the at least one encoder being configured to provide a primary motor control
Data Source
AI summary
An actuator device includes a housing, parallel rolling screws supported in the housing, an actuator element, an actuator spindle anchored in the actuator element, a control system, sensor heads, and position sensors. Each rolling screw is coupled to an electric motor and engages a roller nut. Rotating the rolling screws axially displaces the rolling nuts. The actuator element engages with each rolling nut. One sensor head is arranged on the actuator element near each roller nut. One position sensor is fastened in the actuator adjacent each sensor head and communicates position information of each sensor head to the control system. Each electric motor has an encoder coupled to the control system. The encoder provides a primary motor control. The control system compares information from each position sensor with information from the encoder. The information from each position sensor acts as a secondary position control of the actuator element.