Encoder Communication Pull-Up Switching to Prevent Surge Faults
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Solution Overview
Problem
The connection of a communication line to a power supply via a pull-up resistor in a work machine can cause surge currents and malfunctions in an encoder when attached or detached, leading to potential failures.
Innovation Solution
A control device with a first switch in the electrical path connecting a pull-up resistor and a power supply, controlled by a controller, to interrupt or complete the path, preventing surge currents and sudden interruptions during encoder attachment or removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the communication line is connected to the power supply via a pull-up resistor, then the communication function is enabled, but surge current flows to the encoder when attached or detached causing failure or malfunction
Solution Approach 1:
The controller interrupts the electrical path between the power supply and pull-up resistor before the encoder is attached to the control device. This preliminary action prevents surge current from flowing to the encoder during attachment, eliminating the harmful effect while maintaining communication functionality
Solution Approach 2:
The controller applies a counter-action by interrupting the power path to the pull-up resistor before encoder attachment occurs. This preliminary anti-action neutralizes the potential surge current threat, allowing safe encoder connection without damage
2Ease of operation
If voltage is applied to the communication line while the encoder is removed, then the communication line is ready for operation, but the encoder may suffer failure or malfunction
Solution Approach 1:
The controller ensures the encoder is properly attached before applying voltage to the communication line. This preliminary sequencing prevents voltage from being applied to a removed encoder, eliminating the risk of damage while maintaining operational readiness
3Ease of operation
If the encoder can be freely attached and detached from the control device, then ease of installation and removal is achieved, but surge current and sudden interruptions cause encoder failure
Solution Approach 1:
The system dynamically adjusts the power supply state based on encoder attachment status. The controller monitors encoder presence and automatically interrupts or enables the power path to the pull-up resistor, allowing free encoder attachment/detachment while maintaining reliability through adaptive control
Solution Approach 2:
The controller detects whether the encoder is attached or removed and provides feedback control by adjusting the switch state accordingly. This feedback mechanism ensures the power path is interrupted when encoder is removed and enabled when attached, preventing surge current while maintaining ease of operation
Data Source
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AI summary
To suppress occurrence of a failure or a malfunction in an encoder via a communication line when the encoder is removed from and attached to a control device. Control device (2) is a control device that controls motor (4) based on a detection signal of encoder (3) that detects an operation position of motor (4). Control device (2) includes communicator (22), pull-up resistor (R1), first power supply (26), first switch (SW1), and controller (27). Communicator (22) transmits and receives a detection signal to and from encoder (3) via communication line (L2). Pull-up resistor (R1) is connected to communication line (L2). First switch (SW1) is provided in first electrical path (L7) connecting first power supply (26) and pull-up resistor (R1), and completes and interrupts first electrical path (L7). Controller (27) controls first switch (SW1).