Steering Motor Uncommanded Motion Detection via Dynamic Integration
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Solution Overview
Problem
Conventional differential steering systems for track-type tractors fail to effectively detect and respond to uncommanded motion, particularly at varying speeds and under different operating conditions, leading to potential accidents and inefficiencies due to fixed speed thresholds and duration limits that do not account for internal and external factors affecting vehicle responsiveness.
Innovation Solution
A differential steering control system that uses a control unit to monitor and compare actual steering motor speed to commanded speed, calculates a weighted steering motor speed based on actual speed, and integrates this over time to determine a cumulative value for uncommanded motion, triggering a response strategy when the cumulative value exceeds a dynamically adjusted limit considering factors like oil temperature and vehicle responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed speed thresholds and duration limits are used for detecting uncommanded motion, then the detection system is simple to implement, but the system produces false trips at low speeds and excessive uncommanded motion at high speeds
Solution Approach 1:
The patent applies dynamics by making the detection thresholds and response parameters variable rather than fixed. The system dynamically adjusts speed thresholds, integration limits, and response timing based on the actual operating speed of the vehicle. At higher speeds, the system uses lower thresholds and shorter integration periods to detect uncommanded motion more aggressively, while at lower speeds, it uses higher thresholds and longer integration periods to avoid false trips. This dynamic adaptation resolves the contradiction between simple fixed-threshold implementation and reliable speed-dependent detection accuracy.
2Loss of time
If the speed threshold is lowered and duration limit is shortened to react quickly to uncommanded motion at high speeds, then the response time to uncommanded motion is improved, but the number of false trips increases
Solution Approach 1:
The patent applies parameter changes by systematically varying multiple detection parameters based on operating speed. The control unit adjusts the speed threshold, integration time limit, and cumulative integration value limits as functions of the current vehicle speed. This coordinated parameter adjustment allows the system to maintain optimal detection sensitivity across the entire speed range, achieving fast response at high speeds without generating false trips at low speeds.
3Reliability
If the speed threshold is raised and duration is lengthened to reduce false trips at low speeds, then the false trip rate is reduced, but the delay in stopping the tractor for uncommanded motion at high speeds increases
Solution Approach 1:
The patent resolves this contradiction by implementing speed-dependent parameter changes where the detection sensitivity parameters are inversely related to operating speed. The control unit calculates appropriate threshold values and integration limits based on the current speed, ensuring that the system is more sensitive and responds faster at high speeds while being less sensitive at low speeds. This dynamic parameter adjustment simultaneously achieves low false trip rates and minimal stopping delays across all operating conditions.
4Device complexity
If a fixed integration limit is used for uncommanded motion detection, then the control logic is simple, but the system cannot adapt to varying operating conditions such as oil temperature and vehicle responsiveness
Solution Approach 1:
The patent applies dynamics by transforming the fixed integration limit into a dynamic, speed-dependent parameter. The control unit calculates the integration limit as a function of current vehicle speed and operating conditions. This allows the system to adapt its detection sensitivity to match the vehicle's responsiveness at different speeds and environmental conditions, resolving the contradiction between simple fixed-limit logic and adaptive detection capability.
Data Source
AI summary
In a machine having a differential steering control system, uncommanded motion may be determined by comparing an actual speed of a steering motor to a commanded turn direction signal from an operator. Where uncommanded motion is occurring, the steering motor speed and time-rate-of-change of the steering motor speed may be used to determine a weighted steering motor speed that is accumulated over a series of sample cycles and compared to an integration limit to determine whether the operator should be warned of the occurrence of uncommanded motion. The integration limit may be based on a factor indicative of the responsiveness of the machine, such as the oil temperature.