Intrinsically Safe Joystick With Cam-Modulated Resetting Torque
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Solution Overview
Problem
Operator control elements like joysticks in utility vehicles and construction machines lack intrinsic safety, as they can deflect without user input due to force feedback system malfunctions, potentially causing unintended machine movement, and existing solutions do not ensure independent joystick movement is ruled out or prevent automatic return to neutral position in case of failures.
Innovation Solution
Incorporating an actuator unit connected to a resetting unit that modulates resetting torque, ensuring a positive torque for returning to neutral state and limiting user-dependent deflection torque, allowing the joystick to remain usable even with system failures, and using compliance elements and cam-probe combinations for haptic feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If force feedback is implemented using electric motors and gear mechanisms, then haptic feedback is provided to the user, but the joystick can deflect automatically without user input due to control malfunctions
Solution Approach 1:
A cam mechanism serves as an intermediary between the electric motor and the activation lever. The cam translates the motor's linear or rotational motion into a controlled torque applied to the lever, providing haptic feedback while maintaining mechanical predictability and safety through geometric constraints rather than direct electronic control
Solution Approach 2:
The system pre-configures the cam geometry and spring characteristics to ensure that the resetting torque always exceeds any potential deflection torque from motor failures. This preliminary mechanical design prevents automatic deflection before it can occur, rather than relying on detection and response to failures
2Reliability
If redundant electronic monitoring is used to prevent automatic movement, then safety is improved, but system complexity and cost increase
Solution Approach 1:
The patent replaces complex electronic monitoring systems with a purely mechanical solution using cams, springs, and geometric constraints. The cam profile and spring constants are designed to inherently prevent automatic deflection, eliminating the need for sensors, controllers, and monitoring electronics while maintaining intrinsic safety
3Reliability
If the resetting torque is increased to ensure automatic return to neutral, then the joystick returns reliably to neutral position, but the joystick becomes harder for users to deflect intentionally
Solution Approach 1:
The cam mechanism is designed to provide dynamic, position-dependent torque characteristics. The cam profile varies the resetting torque throughout the lever's range of motion, providing higher torque near the neutral position for reliable return while allowing easier deflection at extreme positions, creating a natural mechanical characteristic that balances safety and usability
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 solution ensures the joystick returns to its neutral position automatically and remains usable during system failures, preventing unintended movement and maintaining user control, while allowing for customizable haptic feedback and reduced need for redundant electronic monitoring.
Implementation Method 1
the resetting unit has a compliance element (4), wherein the actuator unit (3) is designed to modulate a resetting characteristic of the compliance element (4)
Implementation Method 2
the actuator unit is designed to perform limited modulation of the resetting torque, wherein in the case of a lower modulation limit the resetting torque is greater than zero in the deflected state
Data Source
AI summary
The present invention relates to an operator control element, in particular a joystick, comprising a housing, an activation lever which is mounted in the housing so as to be pivotable about a pivot point, and a resetting unit for making available a resetting torque for resetting the activation lever from a deflected state into a neutral state. In order to specify an operator control element which makes available a haptic force feedback which is intrinsically safe, the invention proposes that the operator control element comprises an actuator unit which is operatively connected to the resetting unit, wherein the actuator unit is designed to perform limited modulation of the resetting torque, wherein in the case of a lower modulation limit the resetting torque in the deflected state is greater than zero.