Motor Drive Control for Automatic Injection Device Reset
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Solution Overview
Problem
Existing medication delivery devices face challenges in automatically resetting after detecting a motor stall event, which can lead to user difficulties and inefficiencies, particularly for individuals with impaired vision or reduced dexterity.
Innovation Solution
The device incorporates a control system with a drive signal generator and encoder to detect motor slip, allowing for automatic adjustment of operational control to reset the device to a target state, such as a dose reset or cartridge replacement position, without user interaction, using stepper pulses and reference points to determine the quantum of slip and adjust the motor drive accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the device requires manual resetting after motor stall detection, then the control system is simpler, but user convenience deteriorates and operation time increases
Solution Approach 1:
The control system automatically detects motor stall conditions through encoder feedback and initiates reset procedures without user intervention. The system monitors the relationship between input drive signals and encoder output signals, and when a stall is detected, the control means autonomously determines the quantum of slip and executes the appropriate reset action, making the device serve itself.
Solution Approach 2:
The encoder provides continuous feedback on the output drive of the motor, allowing the control means to compare the actual motor position with the commanded position. This feedback mechanism enables automatic detection of motor slip or stall conditions, triggering the reset sequence when discrepancies exceed predetermined thresholds.
2Ease of operation
If the device performs automatic reset after motor stall, then user convenience improves, but device complexity increases
Solution Approach 1:
The control system automatically detects motor stall conditions through encoder feedback and initiates reset procedures without user intervention. The system monitors the relationship between input drive signals and encoder output signals, and when a stall is detected, the control means autonomously determines the quantum of slip and executes the appropriate reset action, making the device serve itself.
Solution Approach 2:
The patent replaces manual mechanical resetting operations with an automated electromechanical control system. The control means uses electronic signal processing and motor control to achieve reset functions that would otherwise require manual user actions, substituting electronic automation for mechanical user intervention.
3Measurement precision
If the motor is deliberately stalled against a reference point for reset, then positioning precision improves, but energy consumption increases
Solution Approach 1:
The control system deliberately stalls the motor against a predetermined reference point (such as a backstop) to establish a known starting position for the reset sequence. This preliminary positioning action ensures accurate reference for subsequent dose delivery operations, even though it consumes additional energy momentarily.
Solution Approach 2:
The motor is deliberately stalled beyond normal operation requirements to achieve precise positioning at a reference point. This excessive action (deliberate stalling) is performed only when needed for reset operations, not during normal dose delivery, thereby limiting energy consumption to only when necessary for accurate positioning.
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
This solution enables automatic device reset and reduces motor stall noise, improving battery life and user convenience by eliminating the need for manual intervention after a motor stall event.
Implementation Method 1
a drive mechanism including a motor for providing an output drive to the piston rod
Implementation Method 2
an encoder for generating an encoder output signal indicative of the output drive of the motor
Data Source
AI summary
This invention relates to an injection device for delivering a medicament to the human or animal body, in particular, but not exclusively, to a device having a replaceable medicament cartridge, including an auto-injector, wherein the injector device comprises: a housing; a piston rod for driving a bung of a medicament container; a drive mechanism including a motor for providing an output drive to the piston rod for delivering the medicament; and control means for controlling operation of the device.