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Smart Sensor Module For Mission Critical Applications
Problem
Many complex, high-speed, multifunction systems require an appropriate response to environmental or internal changes quickly. Correlation between the physical or environmental characteristics being monitored and the circuit parameters must be determined to generate an appropriate response.
An appropriate response requires three actions to occur within a critical time frame. The system must first monitor the primary input signals for changes. Then the system must detect whether those changes exceed predetermined limits (limits can be variable depending on current conditions). Lastly, action must be taken. The action can be as simple as notifying the system or operator of the status through a signal or indicator. Alternatively, the action could consist of making intelligent decisions based on multiple detector information.
For Mission Critical applications high reliability components must be selected and their interactions must be carefully reviewed.
Monitor
To build a reliable application the first challenge is to determine which variables need to be watched for further processing later. Critical variables need to be determined and a suitable method for monitoring them must be implemented.
Possible Variables:
Frequency - The system could watch for the presence of a signal source such as if a clock fails and has no frequency output. On the other hand it could monitor for a frequency source to be out of tolerance. This can occur when an oscillator fails to start properly.
Current of Voltage - Monitoring a hot swappable device or component for current or voltage could help the system determine whether the item has been removed or is installed. If it is removed it will cease to draw current and it will begin again once it is replaced. The current or voltage levels could also be monitored to determine when lower or upper limits are met or exceeded.
Motor Speed - When a device starts, stops, slows down or speeds up could also be determined by the monitoring system. The system could determine when upper or lower limits for speed or acceleration are met or exceeded.
Position - Both rotational and linear position could be monitored. Rotational shaft positions can be determined for less than a 0º10' change in the angle. Linear position could also be determined using a conversion from rotational information.
Detect
The detection phase processes the information from the monitoring methods that have been selected. Detection would determine whether they pass, fail or meet other criteria that requires action.
Microcontrollers can serve many of these purposes today. But the signal must be in a digital form if it is not already. This can be done using an analog/digital conversion or analog comparitors. Analog comparitors detect analog limits using the reference voltage as a limit voltage for the application.
Action
Action must be taken once detection has been accomplished and it is determined that the inputs have met the necessary criteria. The required action could range from simply alerting the operator with an indicator light to making an intelligent decision based on multiple sources of information.
Defining the reaction to detection information is critical in creating a viable system. The system must also respond to the correct degree for different ranges of information.
Examples of Actions:
Reporting - Making the system or the operator aware of the conditions that have been detected is the simplest action. This might include simply setting a digital bit high or low to indicate a change or lighting an LED to indicate to an operator that the status has changed. A report to the system may also consist of a more complex digital signal.
Switching - The action could cause the system to switch to alternate or backup sources if a device fails or its condition changes. The system could also switch off the failed device or switch on another device.
Adjustments - If certain criteria are detected the system could make changes to any number of outputs including motor speed, rotational position, frequency or amplitude.
Why NEL Frequency Controls?
The module concept allows our engineers to develop plug and play devices for your applications. You will not have to worry about any engineering considerations for capturing inputs and configuring outputs and actions. You just let us know what the inputs and action thresholds are along with what actions need to be taken and we take care of the details.
We currently have a patent pending for the control loop sensing upon which Monitor, Detect, Action systems are built. Our engineers have vast experience with creating high reliability frequency control devices and motion control encoders. Our work in these areas has included numerous miniaturization and signal conditioning projects. This experience allows us to build mission critical control systems for almost any requirements.
Our past experience includes a range of monitor, detect, action and other applications:
- Mixed signal knowledge - We have worked with and interfaced between many different digital technologies, analog signals, RF signals, and microwave signals
- RF, analog and EMI filtering
- Noise source generation - generating noise sources for controlled noise injection
- Reliability Quality issues - HALT concepts, FIT rate calculations, long term aging affects, moisture levels and cleanliness/contamination issues
- Reliability Physics - Electronic component failure mechanisms
- Frequency domain and time domain relationships
- Control loops - phase locked loops, motor control loops, micro controller
- Encoder technologies - absolute and incremental, optical and hall affect, digital or analog outputs
- Redundancy concepts for mission critical applications
- Quartz crystal design and processing
- Oscillator design and manufacture
- Hybrid electronic packaging including hermetic seal, ceramic and glass to metal packaging.
- Signal integrity applications such as transmission lines, impedance matching, jitter issues and phase noise issues.
- Miniaturization - We commonly work with extremely small size components and creative packaging to miniaturize circuits. Some standard components we have worked with are bare IC DIE, thick film resistors to reduce overall size 0402 chip components. IC DIE stacking to save space is one example of our creative packaging solutions.