Tracking Loop Angle Converter With 180° Error Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing tracking loop type digital angle converters experience a drop in response control when the angle error approaches 180°, leading to a hang-up state where the monitored object is left with significant angular deviation, as the control deviation becomes small and unstable.
Innovation Solution
Incorporating a detected signal sign judging section and an output angle correcting section that phase-shifts the output angle by 180° when an excessive angle error is detected, ensuring the converter remains in a high convergence state by comparing the quadrant of the input angle with the output angle and inverting the most significant bit of the counter to correct the output angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the control deviation is represented by sin(θ - φ) in a tracking loop, then the converter operates with simple control logic, but the control response drops when the angle error approaches 180° causing a hang-up state
Solution Approach 1:
The patent applies preliminary action by detecting the quadrant of the input angle θ in advance and comparing it with the quadrant of the output angle φ before the angle error reaches 180°. When a quadrant difference is detected, the output angle φ is proactively corrected by 180° to prevent the control response drop and hang-up state from occurring. This anticipatory correction maintains reliable control response while keeping the control logic relatively simple.
2Measurement precision
If the angle error (θ - φ) becomes close to 180°, then the control deviation sin(θ - φ) becomes small, but the angle error is large causing poor control accuracy
Solution Approach 1:
The patent implements feedback by continuously monitoring the quadrant relationship between the input angle θ and output angle φ. When the quadrants differ, indicating an angle error close to 180°, the system feeds back a correction signal to adjust the output angle φ by 180°. This feedback mechanism ensures that the angular position accuracy is maintained despite the control deviation sin(θ - φ) becoming small at large angle errors.
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A tracking loop type digital angle converter (20') that operates so that a deviation between input and output angles always becomes zero by feeding back the output angle to the input angle using a tracking loop (22A,22B,23-27). In order to eliminate a case where an angle error between the input and output angles is in the vicinity of 180°, i.e., where the tracking loop response becomes low, there are provided a detected signal sign judging section (41) that judges the signs of the rotation detection signals (S1,S2) to determine the quadrant wherein the input angle (θ) lies, and an output angle correcting section (42) for comparing an angle region of the output angle (Φ) and said quadrant of the input angle (θ) to detect whether said angle error is excessive, whether the control response is low and to carry out a process for compensating the output angle (Φ), when this is the case. The tracking loop digital angle converter may be used in an angle-to-digital converting apparatus.