Haptic Actuator Closed-Loop Control Eliminates Mechanical Stop Noise
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Solution Overview
Problem
Haptic devices face challenges in providing precise tactile feedback without mechanical limit stops, which can result in noise due to the field member crashing into stops, and existing solutions fail to effectively calibrate and control the haptic actuator for smooth operation.
Innovation Solution
An electronic device with a haptic actuator that includes a closed-loop controller capable of determining calibration based on drive voltage, current, and position, allowing the actuator to operate in a closed-loop configuration without mechanical limit stops, using a driver and position sensor to track the field member's movement and velocity, and store reference patterns for different operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical limit stops are used to constrain the field member movement, then the actuator structure is simple and reliable, but noise is generated when the field member crashes into the stops
Solution Approach 1:
The patent replaces the mechanical limit stop system with an electronic control system. The closed-loop controller monitors the field member position via position sensor and actively controls the driver to prevent the field member from reaching the mechanical limit stops, thereby eliminating impact noise while maintaining structural simplicity.
Solution Approach 2:
The patent implements a closed-loop control system where the position sensor continuously monitors the field member position and feeds this information back to the closed-loop controller. The controller adjusts the drive signal in real-time to ensure the field member operates within the safe range, preventing contact with mechanical limit stops and eliminating impact noise.
2Length of moving object
If the field member operates close to mechanical limit stops to maximize travel range, then the actuator provides larger displacement, but impact noise is generated
Solution Approach 1:
The closed-loop controller uses real-time position feedback from the position sensor to maintain the field member at optimal positions that maximize travel range while maintaining a safety margin from the mechanical limit stops. This feedback mechanism ensures the field member operates close to but never contacts the stops, maximizing displacement without generating impact noise.
Solution Approach 2:
The system performs preliminary positioning by actively controlling the field member to stop at predetermined positions that maximize travel range before the mechanical limit stops are reached. The closed-loop controller anticipates the approach to limit stops and adjusts the drive signal in advance to prevent contact, thereby maximizing displacement while avoiding impact noise.
3Measurement precision
If open-loop control is used for simplicity, then the control system is less complex, but precise tactile feedback cannot be achieved
Solution Approach 1:
The patent implements closed-loop control where the position sensor provides real-time feedback on the field member position to the closed-loop controller. This feedback enables precise control of the haptic actuator's movement, allowing for accurate tactile feedback generation while maintaining a manageable control system architecture.
Solution Approach 2:
The patent replaces simple open-loop mechanical control with an electronic closed-loop control system. The position sensor and closed-loop controller work together to precisely control the field member position and velocity, enabling accurate tactile feedback generation through electronic control rather than mechanical means.
4Measurement precision
If calibration is performed to improve actuator precision, then tactile feedback accuracy is enhanced, but additional control processing is required
Solution Approach 1:
The patent performs calibration of the haptic actuator parameters (such as mass, damping coefficient, and stiffness) in advance during the initialization phase. The closed-loop controller stores these calibrated parameters and uses them for precise control operations, thereby improving tactile feedback accuracy without requiring complex real-time processing during actual haptic operations.
Solution Approach 2:
The patent determines calibration parameters (mass, damping coefficient, stiffness) that characterize the specific haptic actuator hardware. These parameters are used by the closed-loop controller to optimize control signals and achieve precise tactile feedback. The calibration process transforms generic control into customized control tailored to the specific actuator's physical characteristics.
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
Enables smooth operation of the haptic actuator without mechanical limit stops, reducing noise and improving the precision of tactile feedback by calibrating and controlling the device based on real-time data, allowing for various haptic feedback modes.
Implementation Method 1
The haptic actuator may include at least one coil carried by the housing. The field member may be movable within the housing responsive to the at least one coil
Implementation Method 2
The position sensor may include at least one of a capacitive sensor, an optical sensor, and a magnetic sensor
Implementation Method 3
The closed-loop controller may be capable of driving the haptic actuator in a closed-loop configuration based upon the calibration of the haptic actuator and at least one reference pattern of movement of the field member
Data Source
AI summary
An electronic device may include a haptic actuator that may include a housing and a field member movable within the housing, and a driver capable of driving the haptic actuator and sensing at least one of a drive voltage and drive current for the haptic actuator. The electronic device may also include a closed-loop controller cooperating with the driver. The closed-loop controller may be capable of determining a calibration of the haptic actuator based upon at least one of the drive voltage and drive current, storing a reference pattern of movement for the field member, and driving the haptic actuator in a closed-loop configuration based upon the calibration of the haptic actuator and reference pattern of movement of the field member.