Zero Turn Mower Stability Control Using Gyroscope Feedback
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Solution Overview
Problem
Existing stability control systems for utility vehicles with electrically-powered drives, such as zero turn mowers, face challenges in maintaining straight line tracking, wheel slip and traction control, and rollover protection, especially on uneven terrain and slopes, often requiring complex front wheel steering mechanisms or operator differential steering, and rely on costly wheel speed sensors.
Innovation Solution
A stability control system utilizing a 3-axis gyroscope, 3-axis accelerometer, and input from the vehicle's accelerator and steering system, without the need for wheel speed sensors, to provide enhanced straight line tracking, wheel slip and traction control, and rollover protection by adjusting motor control signals based on environmental conditions and operator inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wheel speed sensors are used for stability control, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the wheel speed measurement function from dedicated wheel speed sensors and relocates it to the existing gyroscope and accelerometer system. The gyroscope measures yaw rate and the accelerometer measures lateral acceleration, both of which contain information about wheel speed through vehicle dynamics relationships, eliminating the need for separate wheel speed sensors.
Solution Approach 2:
The gyroscope and accelerometer are made multi-functional by using them not only for their primary stabilization functions but also for deriving wheel speed information. This universal use of existing sensors eliminates the need for additional dedicated wheel speed sensors, reducing system complexity and cost.
2Stability of the object's composition
If front wheel steering mechanisms are added for straight line tracking, then stability control is improved, but device complexity increases
Solution Approach 1:
The vehicle achieves straight line tracking through self-service by using the gyroscope to detect yaw rate deviations from the desired path and automatically adjusting the ground drive speeds. The system serves its own stabilization needs without requiring external or additional steering mechanisms, using only the existing differential ground drive capability.
Solution Approach 2:
The gyroscope provides continuous feedback on the vehicle's actual heading and yaw rate, which the controller uses to automatically adjust the differential speeds of the ground drives to maintain straight line tracking. This closed-loop feedback system achieves stable tracking without additional steering hardware.
3Stability of the object's composition
If operator differential steering is required for hillside operation, then hillside stability is improved, but ease of operation deteriorates
Solution Approach 1:
The vehicle performs self-service on hillside terrain by using the accelerometer to detect the slope angle and the gyroscope to monitor heading deviations. The system automatically adjusts the ground drive speeds to compensate for gravitational effects and maintain stable operation, eliminating the need for the operator to manually differential steer.
Solution Approach 2:
The accelerometer and gyroscope provide continuous feedback on the vehicle's orientation and position on the hillside, enabling the controller to automatically make real-time adjustments to the ground drive speeds. This feedback loop maintains hillside stability without requiring constant manual intervention from the operator.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively reduces complexity and cost by enabling stable operation on uneven terrain and slopes without additional steering mechanisms, improving operator safety and reducing fatigue through automatic correction and power adjustments, while maintaining vehicle stability and traction.
Implementation Method 1
The system utilizes a 3-axis gyroscope, 3-axis accelerometer, input from the vehicle accelerator and input from the vehicle steering system
Implementation Method 2
The system utilizes a 3-axis gyroscope, 3-axis accelerometer, input from the vehicle accelerator and input from the vehicle steering system
Data Source
AI summary
A drive and control system is disclosed for use on a zero turn vehicle having a pair of drive motors, an operator drive input capable of providing a drive signal corresponding to a desired drive status by an operator and an operator steering input capable of providing a steering signal corresponding to a desired steering of the vehicle. Sensors on the vehicle generate signals corresponding to roll, pitch and yaw. A stability control module includes a processor receiving the steering and drive inputs and provides output signals to the drive motors. Upon initialization of the vehicle, the processor determines initial orientation parameters from the sensors and determines if the input and steering are in neutral. When the drive input is not in neutral, and the steering is in neutral, the processor determines desired pitch, yaw and roll parameters. The processor receives additional sensor signals during operation to monitor pitch and roll of the vehicle and if a measured parameter exceeds the desired parameter, the processor will vary the output signals to the drive motors to provide a heading correction to the vehicle.