Servo Control Apparatus for Master-Slave Axis Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing servo control systems for tandem control of servomotors face issues with integral value divergence between master and slave servomotors, leading to unstable control and potential overheating, especially when the mechanical coupling rigidity between driven objects and axes is low, causing issues like 'flexure' or 'torsion' during quick acceleration or deceleration.
Innovation Solution
A servo control apparatus that calculates and adjusts the integral value of the speed integrator for the slave axis using a difference calculation unit, low-pass filter, and addition unit, while maintaining controllability by adjusting the cutoff frequency of the low-pass filter based on estimated mechanical coupling rigidity, ensuring the integral values of the master and slave axes remain synchronized only when necessary to prevent torsion and maintain control stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the integral value of the speed integrator of the slave side is constantly identical to that of the master side, then the divergence of integral values between servomotors is solved, but position deviation increases when mainly the slave-side servomotor is driven, causing unstable control
Solution Approach 1:
The patent dynamically switches the copy source of the integral value between master and slave sides based on the direction of acceleration. When acceleration is positive, the slave side copies from master; when acceleration is negative, the master side copies from slave. This dynamic adaptation resolves the contradiction by adjusting the control strategy according to operational conditions.
Solution Approach 2:
The patent changes the parameter of which servomotor's integral value serves as the reference (copy source) based on acceleration direction. This parameter change allows the system to maintain integral value synchronization while preventing position deviation under different operating conditions.
2Reliability
If the integral values of the speed integrators are constantly identical to each other, then integral value divergence is prevented, but when mechanical coupling rigidity is low, the driven object may be elastically deformed causing flexure or torsion
Solution Approach 1:
The patent dynamically adjusts the synchronization strategy based on acceleration direction and mechanical coupling rigidity. By switching which servomotor's integral value serves as the reference, the system prevents excessive torque commands that would cause torsion in low-rigidity mechanical couplings while maintaining control stability.
Solution Approach 2:
The patent applies preliminary anti-action by anticipating the harmful effect of torsion before it occurs. By switching the copy source based on acceleration direction, the system prevents the generation of excessive torque commands that would cause elastic deformation in low-rigidity mechanical couplings.
3Ease of operation
If each servomotor receives speed feedback at different timing, then independent control is maintained, but integral values of integral elements of speed control units diverge, deteriorating controllability
Solution Approach 1:
The patent merges the integral values of the master and slave servomotors by making one copy the other based on acceleration direction. This merging prevents divergence while maintaining independent speed feedback reception, thus preserving individual controllability while ensuring coordinated operation.
Solution Approach 2:
The patent uses feedback from acceleration direction to determine which servomotor's integral value should be the reference. This feedback mechanism ensures that integral values remain synchronized despite different speed feedback timing, maintaining system controllability.
Data Source
AI summary
A servo control apparatus which includes: a difference calculation unit that calculates difference between an integral value of speed deviation of a master axis and an integral value of speed deviation of a slave axis; a filter unit that performs filtering of the difference by way of a low-pass filter; and an addition unit that adds a result of the filtering to the integral value of the speed deviation of the slave axis, in which a current command for driving the master-axis motor is calculated for the master axis by using the integral value of the speed deviation of the master axis; and a current command for driving the slave-axis motor is calculated for the slave axis by using an integral value after addition by way of the addition unit.