Feedback Control Buffering for Variable Network Delay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing feedback control systems face instability due to varying dead times in communication networks, particularly in low-speed wired or wireless connections, leading to ineffective control without the use of clock functions.
Innovation Solution
A control system that includes a sensor adding a transmission sequence number to physical quantities, a buffer unit holding an array of elements based on maximum delay periods, and a control unit generating control signals using reception and transmission sequence numbers to stabilize feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If feedback control is performed using physical quantities transmitted through communication networks with varying dead times, then control flexibility and remote operation capability are improved, but control stability deteriorates due to timing variations
Solution Approach 1:
The patent applies preliminary action by storing multiple past physical quantity values in a buffer before control calculation. The control device prepares a history of received physical quantities (y[-1], y[-2], ..., y[-N]) in advance, so that even when dead time varies, the appropriate past value is already available for accurate feedback control without requiring precise timing synchronization.
2Measurement precision
If clock functions are used to synchronize timing between transmission and reception sides, then control precision is improved, but system complexity increases due to requiring clock functions in both sides
Solution Approach 1:
The patent extracts the timing synchronization requirement from the system by eliminating the need for clock functions in both transmission and reception sides. Instead of using active timing synchronization, the invention uses a passive buffer-based approach where the control device stores physical quantities with their timing information and selects the appropriate value based on current timing, thereby removing the complexity of bidirectional clock synchronization while maintaining control precision.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
Even when a delay time varies, stable control can be performed without using a clock function. A control device (10) configured to perform feedback control by transmitting a control signal to a target device (20) based on a physical quantity of the target device (20) measured by a sensor (30) and a command value includes: a receiver (13) configured to receive the physical quantity to which a transmission sequence number incremented for each control cycle is added in a sensor driver (35); a buffer unit (14) configured to hold an array of a number of elements determined based on a maximum value of a number of delay periods; a control unit (11) configured to generate the control signal based on the physical quantity and the command value; and a transmitter (12) configured to transmit the control signal to the target device (20). The control unit (11) increments a reception sequence number for each control cycle, stores the physical quantity at a storage position of an array determined based on the transmission sequence number and the reception sequence number, and generates the control signal based on the physical quantity stored in a storage position for control, and the command value.