Assisted Lawnmower Steering Using IMU Feedback on Slopes
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Solution Overview
Problem
Lawnmowers often deviate from the desired path due to gravitational and terrain forces, leading to undesirable steering effects such as turning downhill or veering off course on uneven surfaces.
Innovation Solution
An assisted steering system for lawnmowers that uses an inertial measurement unit (IMU) and a controller to adjust motor speeds based on user input and gain profiles, applying varying degrees of corrective steering to maintain direction, especially on slopes and bumpy terrain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional steering control is used without assistance, then the system is simple and responsive to user input, but the lawnmower deviates from the desired path due to gravitational and terrain forces
Solution Approach 1:
The steering control system receives feedback from the IMU about the lawnmower's actual orientation and compares it to the desired orientation. The controller automatically generates corrective steering commands based on this feedback to counteract deviations caused by gravitational and terrain forces, thereby improving path following accuracy without requiring complex mechanical modifications
Solution Approach 2:
The patent replaces mechanical steering assistance mechanisms with an electronic control system that uses an IMU and motor control. The controller electronically processes orientation data and generates motor control signals to adjust wheel speeds, substituting complex mechanical steering linkages with a more compact and controllable electronic system
2Reliability
If the steering system applies strong corrective forces to maintain direction, then path following accuracy improves, but the steering becomes jerky and less smooth
Solution Approach 1:
The steering control system dynamically adjusts the magnitude of corrective commands based on the detected deviation and current operating conditions. The controller modulates the corrective force applied to each wheel, increasing correction strength when deviations are large and reducing it when the lawnmower is near the desired path, thereby maintaining both accuracy and smooth operation
Solution Approach 2:
The control system continuously monitors the lawnmower's orientation and applies periodic corrective adjustments rather than single large corrections. By making frequent, small adjustments based on continuous IMU feedback, the system maintains smooth steering while effectively counteracting gravitational and terrain-induced deviations
3Speed
If the steering system responds quickly to user input, then maneuverability improves, but the system becomes more sensitive to terrain disturbances and bumps
Solution Approach 1:
The control system applies preliminary corrective action by anticipating deviations before they become significant. The IMU continuously monitors orientation, and the controller proactively generates corrective commands to prevent large deviations from occurring in the first place, allowing quick response to user input while maintaining stability
Solution Approach 2:
The steering control system dynamically adjusts its responsiveness based on detected terrain conditions and current motion state. When terrain disturbances are detected, the controller modulates the gain of steering corrections, reducing sensitivity to bumps while maintaining quick response to deliberate user steering inputs, thereby balancing maneuverability and stability
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 provides smooth and precise steering control, minimizing jerking and wavering while allowing quick turns, ensuring the lawnmower stays on course despite external forces.
Implementation Method 1
An assisted steering system for lawnmowers that uses an inertial measurement unit (IMU) and a controller to adjust motor speeds
Implementation Method 2
when traversing a slope, the lawnmower will often tend to turn downhill as a result of gravitational force acting on the lawnmower
Implementation Method 3
a motor operably coupled to drive the wheel
Data Source
AI summary
A lawnmower including: a wheel; a motor operably coupled to drive the wheel; a user input configured to receive a steering control input from a user; and a controller configured to operate in a steering assist mode where the controller: receives information from the user input, the information including a position of the user input; compares the position of the user input to a gain profile saved in a memory of the controller; determines a scale factor from the gain profile based on the comparison; generates a command instruction to control a speed of the motor based on the position of the user input and the determined scale factor; and transmits the command instruction to the motor to affect a speed of the motor.