Sensor-less Motor Reversal Apparatus for UAVs
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Solution Overview
Problem
Unmanned aerial vehicles (UAVs) face design complexities in balancing stability, maneuverability, and energy efficiency, with current systems struggling to maintain control and safety in degraded operational states and lacking agility and maneuverability enhancements.
Innovation Solution
The development of a sensor-less motor reversal (SLMR) apparatus for UAVs, which includes an RPM-dependent clutch, engageable shaft, energy storage mechanism, and latch release mechanism to aid in reversing motor direction, particularly useful for hex-rotor UAVs, enabling thrust reversal and enhancing stability and maneuverability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motor direction reversal is implemented using traditional sensor-based methods, then control precision is improved, but device complexity increases due to additional sensors and control systems
Solution Approach 1:
The patent extracts and removes the sensor component from the motor reversal control system. By using the existing back-EMF signals from the brushless DC motor without adding external sensors, the system achieves accurate rotor position detection and motor reversal control while eliminating the complexity associated with additional sensors and their mounting, wiring, and calibration.
Solution Approach 2:
The patent uses the existing back-EMF signals (which naturally occur during motor operation) as a substitute for dedicated sensor signals. By processing and interpreting these existing electrical signals to determine rotor position and control reversal, the system replicates the functionality of sensor-based control without requiring physical sensor copies or additional measurement hardware.
2Adaptability or versatility
If motor reversal control is added to enhance maneuverability, then agility is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent makes the existing motor control system multi-functional by enabling it to perform both normal forward rotation control and reversal control using the same back-EMF detection and commutation logic. The control system universally handles both operational modes without requiring separate control circuits or mechanisms, thereby enhancing agility while avoiding additional complexity.
Solution Approach 2:
The motor system performs its own position detection and reversal control using its inherent back-EMF signals. The system is self-sufficient in determining rotor position and executing reversal commands without external sensor input or additional control hardware, allowing enhanced maneuverability through internal resource utilization rather than external additions.
3Reliability
If traditional motor reversal methods are used, then reliability may be compromised in degraded operational states, but adding protective measures increases device complexity
Solution Approach 1:
The patent implements continuous feedback monitoring of the back-EMF signals to detect rotor position, speed changes, and operational anomalies. By constantly analyzing the electrical feedback from the motor windings, the system can identify degraded states such as one-propeller failures and automatically adjust control parameters to maintain stable operation and prevent further failures, enhancing reliability through intelligent monitoring rather than mechanical redundancy.
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 SLMR apparatus allows for reliable motor direction reversal without additional sensors, improving UAV stability, agility, and maneuverability, especially in degraded operational states, by facilitating smooth transitions through low RPM ranges and maintaining control during motor reversals.
Implementation Method 1
an energy storage mechanism that is rotated by the engageable shaft from a first position to a second position when the engageable shaft is rotated in the positive direction as a result of a first engagement by the RPM dependent clutch as the RPM of the drive shaft increases from a zero RPM toward the positive RPM, wherein the energy storage mechanism stores a first energy when in the second position
Implementation Method 2
an RPM dependent clutch that is coupled to and rotates with the drive shaft of the brushless DC motor and is operable to engage and rotate the engageable shaft during a low RPM range between a negative RPM of the drive shaft and a positive RPM of the drive shaft and disengage the engageable shaft during a high RPM of the drive shaft that is not between the negative RPM and the positive RPM
Data Source
AI summary
Described is a sensor-less motor reversal (“SLMR”) apparatus that aids the reversal of motor rotation of a bidirectional motor, such as a brushless DC motor of an aerial vehicle. The SLMR includes an RPM dependent clutch that is rotated by a drive shaft of the motor and that engages an engageable shaft of the SLMR apparatus during a low RPM range of the motor during which indirect measurement of the RPM of the motor through a back-EMF of the motor is unreliable. As the engageable shaft increases in RPM, energy is stored by an energy storage mechanism of the SLMR. As the RPM of the motor decreases as part of a motor reversal, the energy stored by the energy storage mechanism is discharged and aids in the transition of the reversal of the motor from positive to negative, or negative to positive. As described, the SLMR apparatus is stateless.