Traveling Vehicle Motor Control Switching for Wheel Lock Prevention
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Solution Overview
Problem
Conventional vehicles using PI or PID control for independent left and right motor control can result in discomfort or 'wrongness' during small-turn maneuvers, particularly at low speeds, due to potential wheel locking or low-speed operation.
Innovation Solution
A traveling vehicle with independently controlled left and right driving wheels employs a control method that switches between PI and P control based on operational parameters, adjusting control periods within a control cycle to smooth transitions and prevent wheel locking, using a setting section to manage control gains and switchover algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PI control is used for controlling motor currents, then vehicle stability is improved, but wheel locking may occur at low speeds causing user discomfort
Solution Approach 1:
The patent applies dynamics by making the control method switchable between PI control and P control based on operational conditions. The control system dynamically adapts by selecting different control strategies: PI control for general stability and P control for low-speed scenarios where wheel locking occurs, thereby resolving the contradiction between stability and user comfort
Solution Approach 2:
The patent changes control parameters by switching between different control methods (PI vs P control) and adjusting the integral term correction gain based on vehicle speed and operational conditions. This parameter adaptation allows the system to maintain stability while preventing wheel locking at low speeds, thus improving both reliability and ease of operation
2Ease of operation
If integral term correction gain is reduced to prevent wheel locking, then user comfort is improved, but vehicle stability control capability deteriorates
Solution Approach 1:
The system dynamically adjusts the integral term correction gain based on real-time operational conditions such as vehicle speed and acceleration. By making the gain adjustable rather than fixed, the system can provide gentle control at low speeds (improving comfort) while maintaining strong stability control at higher speeds (preserving reliability)
Solution Approach 2:
The patent implements parameter changes by modifying the integral term correction gain according to vehicle speed and operational state. The gain is reduced at low speeds to prevent wheel locking and increased at higher speeds to maintain stability control effectiveness, thus resolving the contradiction between comfort and stability
3Ease of operation
If control method switchover is implemented, then user comfort is improved, but control parameter discontinuity may cause instability
Solution Approach 1:
The patent uses the integral term correction gain as an intermediary parameter to smoothly transition between PI control and P control methods. By gradually adjusting the gain rather than making abrupt switches, the system maintains control parameter continuity while still providing the benefits of method switchover for user comfort
4Adaptability or versatility
If small-turn maneuver is performed at low speed, then vehicle maneuverability is improved, but wheel locking occurs causing road surface damage
Solution Approach 1:
The patent changes control parameters by reducing the integral term correction gain and switching to P control at low speeds during small-turn maneuvers. This parameter adjustment prevents excessive motor current and wheel locking, thereby maintaining maneuverability while preventing road surface damage
Data Source
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Figure 3(A)~3(E)
AI summary
A traveling vehicle (1) includes a pair of left and right driving wheels (3), a pair of left and right motors (20) capable of driving the pair of left and right driving wheels (3) independently of each other, an operational amount reception section (51) capable of receiving operational amounts respectively for the pair of left and right motors (20), a setting section (52) capable of setting a period of a first control method having a predetermined first control parameter and a period of a second control method having a predetermined second control parameter, within a predetermined control cycle for controlling driving of the motors (20), in accordance with the operational amounts and a motor driving section (53) capable of driving the respective motors (20) based on result of setting made by the setting section (52).