Position Control Friction Compensation at Very Low Constant Velocity
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Solution Overview
Problem
Conventional position control devices experience tracking delay and reduced accuracy during very low constant velocity operations due to insufficient torque compensation in boundary lubrication regions, particularly when transitioning from hydrodynamic to boundary lubrication states.
Innovation Solution
A position control device that calculates a friction compensation amount based on velocity and acceleration to compensate for friction in very low constant velocity operations, adding it to the torque, velocity, or position command values to enhance tracking precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional position control devices operate in very low velocity regions without specialized friction compensation, then the control system remains simple, but tracking delay and position tracking accuracy deteriorate due to boundary lubrication friction
Solution Approach 1:
The friction compensation calculation unit calculates and applies friction compensation values before the control target actually moves or changes velocity, based on predicted velocity and acceleration. This preliminary friction compensation prevents tracking delay from occurring in the first place, rather than correcting it after the fact.
Solution Approach 2:
The friction compensation value is dynamically adjusted based on real-time velocity and acceleration of the control target. The compensation amount varies continuously with operating conditions, being particularly significant in very low velocity regions where boundary lubrication friction occurs, and decreasing as velocity increases into hydrodynamic lubrication regions.
2Measurement precision
If friction compensation is applied during very low constant velocity operation, then tracking accuracy improves, but the device requires additional calculation complexity to determine very low velocity operation states
Solution Approach 1:
The system uses parameter changes in velocity and acceleration to detect transitions between lubrication regions. By monitoring these physical parameters and comparing them against predefined thresholds, the control device can identify when the control target enters very low constant velocity operation and apply appropriate friction compensation.
Solution Approach 2:
The friction compensation system continuously monitors velocity and acceleration feedback from the control target, uses this information to calculate appropriate compensation values, and adjusts the torque or velocity commands in real-time. This closed-loop feedback ensures accurate tracking even as operating conditions change.
3Speed
If the control target transitions from hydrodynamic to boundary lubrication states, then velocity operation continues, but tracking delay occurs due to insufficient torque compensation
Solution Approach 1:
The system detects the transition from hydrodynamic to boundary lubrication states by monitoring velocity and acceleration parameters, and applies friction compensation in advance before tracking delay can occur. This preliminary compensation ensures continuous reliable tracking even during lubrication state transitions.
Solution Approach 2:
The friction compensation value changes parameters based on the detected lubrication state, increasing significantly when transitioning to boundary lubrication and decreasing when in hydrodynamic lubrication. This dynamic parameter adjustment maintains reliable tracking across different velocity regimes.
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
Effectively reduces tracking delay and improves position tracking accuracy by providing timely friction compensation in very low velocity regions, addressing the insufficiency of conventional torque in boundary lubrication conditions.
Implementation Method 1
add, in response to determining that the control target is in very low constant velocity operation, a friction compensation amount for compensating for friction generated in the very low constant velocity operation
Data Source
AI summary
A position control device for controlling a position of a control target is configured to calculate a velocity command value and a torque command value based on a position command value and a position detection value; determine, based on the velocity command value calculated from the position command value, whether or not the control target is operating at a constant velocity in a very low velocity region in which the velocity of the control target is in a velocity range that is less than or equal to a predefined threshold value; and then add, in response to determining, based on an acceleration command value, that the control target is being in very low constant velocity operation, a friction compensation amount for compensating for friction generated in the very low constant velocity operation to at least one of the torque command value, the velocity command value, and the position command value.