Rotational Speed Signal Resolution via Digital Angle MSB Extraction
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Solution Overview
Problem
Existing rotational speed sensors face challenges in accurately measuring low rotational speeds, leading to delayed or unavailable speed information, which can impact safety in applications like vehicle parking, due to long intervals between pulses and limited bandwidth for additional information transmission.
Innovation Solution
The method involves generating digital angle signals based on the angular position of a rotating physical transmitter field, using most significant bits to create additional rotational speed pulses, and adaptively changing the information output to ensure continuous rotational speed information availability, especially at low speeds, by determining the argument of sinusoidal signals and outputting them as digital angle signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of poles of the transmitter field is increased to increase the number of rotational speed pulses, then the measurement precision of rotational speed is improved, but the bandwidth required for transmitting all rotational speed pulses increases significantly
Solution Approach 1:
The patent extracts only the most significant bits (MSBs) from the digital angle signal for transmission. Instead of transmitting all rotational speed pulses generated by multiple poles, the system outputs a reduced set of pulses corresponding only to the MSBs, thereby reducing bandwidth requirements while maintaining essential measurement precision for control applications
Solution Approach 2:
The patent inverts the conventional approach by not increasing the number of physical poles to increase pulse frequency. Instead, it uses a limited number of poles with a digital signal processing approach, generating virtual additional pulses through MSB extraction from the angle signal, thus achieving high resolution without proportionally increasing bandwidth requirements
2Loss of information
If the number of poles of the transmitter field is increased to increase the number of rotational speed pulses, then the rotational speed information availability is improved, but the space available for transmitting other information between pulses is reduced
Solution Approach 1:
The patent extracts only the essential rotational speed information contained in the MSBs of the angle signal. This selective extraction provides sufficient speed information for control systems while leaving the transmission channel available for other diagnostic and control information to be transmitted in the same communication medium
Solution Approach 2:
The transmission system achieves multi-functionality by simultaneously transmitting rotational speed information (through MSB-based pulses) and other vehicle diagnostic/control information through the same communication channel, making the system versatile without requiring separate dedicated channels for each function
3Loss of information
If the interval between rotational speed pulses is reduced to improve low-speed measurement, then the rotational speed information availability is improved, but the time required to transmit other information between pulses is reduced
Solution Approach 1:
The patent extracts rotational speed information at key angular positions (MSBs) rather than continuously transmitting at every pole passage. This provides adequate speed information for low-speed operation while maintaining sufficient time intervals for transmitting other information, balancing both requirements without requiring excessive transmission bandwidth
Data Source
AI summary
A method for producing sensor information depends on a rotational speed, using a rotational speed sensor which is adapted to output rotational speed pulses in predetermined angular positions of a physical sensor field that rotates at the rotational speed. In order to increase resolution, a digital angle signal each is determined between the pulses. A defined number of most significant bits of said angle information is output to determine the rotational speed so that the interval between two pulses is subdivided into a defined number of subintervals. An angle value which can be unambiguously interpreted by means of the sinusoidal signal can be determined from the cosine signal by using two phase shift sinusoidal signals and an arccos function. The device optionally outputs the angle signal below a threshold value and an impulse signal above the threshold value to determine speed.