Using LabVIEW in the Development of Noise Cancellation Products

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"We at TBG Solutions adapted and implemented an active control algorithm on simple, low-cost hardware by using the stability, versatility, and rapid prototyping potential of LabVIEW, myDAQ, and myRIO."

- Sam May, TBG Solutions

The Challenge:
Developing an active control system to supress structural noise and vibration using low cost, mass production capable hardware.

The Solution:
Creating a two-part system consisting of the mechanical interface and microcontroller, which runs the control algorithm to reduce the transmission of vibrations in a given environment, and the supporting myDAQ systems, which use LabVIEW Real-Time Module code to collect and analyse data.

Author(s):
Sam May - TBG Solutions
Jack Hedges - TBG Solutions

Who We Are

TBG Solutions is a UK-based NI Alliance Partner that specialises in delivering custom test and measurement solutions to high technology companies in industries such as defence, aerospace, and power generation. Working across a wide range of industries gives us the experience to deliver fully integrated and innovative electronics solutions to our customers. We regularly undertake a wide range of work ranging from R&D, electronic product design, proof of concept, demonstrators and prototyping, and production and manufacture. 

Our R&D department focuses on developing innovative products for a range of applications utilising the extensive experience and knowledge within TBG Solutions. NI hardware and software is an integral part of the development cycle of all of TBG Solutions products.

 

Our Application

Machine-induced noise and vibration commonly causes annoyance, health concerns, and material damage. Considerable effort is expended in reducing noise and vibration levels in the home, the workplace, and in transportation. This normally comes in the form of passive damping and screening, in which the vibration is absorbed and dissipated.

In some circumstances it is difficult to reduce the noise and vibration to an acceptably low level using passive methods, particularly if available space or a weight restriction limits the amount of passive damping that can be applied. In these cases, active vibration and noise control can be applied to selectively tune out troublesome vibrations and noises from the machine, whether it is a diesel engine/generator, an air conditioning plant, or any other type of powered system.  

 

How We Solved the Problem

To make a system capable of active cancellation available to a wider market, it needs to be developed on low cost, mass production-capable hardware. This introduces its own set of technical challenges, as these types of hardware can be very challenging to debug, and often do not include the tools to collect, store and analyse data.

We developed an active control system using an embedded microcontroller to control actuators placed on a vibrating body. The microcontroller runs an active control algorithm that we developed from mathematical algorithms developed by the Institute of Sound and Vibration Research at University of Southampton, a partner in the project. We implemented the algorithm in the C programming language and took data from accelerometers located on the vibrating body as a primary input. From this data, the system computes a control signal for the actuators, which vibrate to counteract the vibration in the body.

We used myDAQ, myRIO, and LabVIEW extensively throughout the project development cycle. The ease and speed of development in LabVIEW combined with the versatility of the myDAQ and myRIO devices help the NI ecosystem compensate for the disadvantages of an embedded microcontroller.  

 

Figure 1. myDAQ Used for Test Control and Analysis

 

NI myDAQ Test and Analysis Environment

Our system uses a myDAQ device so an operator can efficiently and accurately test the system. It does this by:

  • Controlling the disturbance vibration, the system will dampen

  • Setting flags on the microcontroller, turning the algorithm on/off to control the test

  • Collecting data from the accelerometers and microcontroller

The test and analysis environment used the rapid prototyping capability of LabVIEW to quickly and efficiently build VIs. We used the DAQ Assistant Express VI to quickly set up I/O channels that could produce a disturbance sinusoid with up to four different frequency components. The impact could be observed in real time from the voltage input from accelerometers on the vibrating body. The test and analysis VI used the powerful ability of LabVIEW to perform an averaged fast Fourier transform (FFT) on the fly to automatically calculate the reduction in power of the vibration at particular frequencies. This helped the operator easily see the impact of the algorithm in real time.

 

Figure 2. Single Actuator, Single Accelerometer Test Diagram Using the myDAQ

 

NI myRIO Plant Response Calculation 

The system also takes advantage of the high-speed FPGA capability of the myRIO for the system’s initial configuration. The accuracy and stability of the algorithm depend on plant response values that specify how the control signal is attenuated between the microcontroller’s control signal output and the resulting accelerometer input. Inaccurate values can cause the algorithm to amplify the vibration rather than damping it, potentially damaging hardware or the vibrating body. Using the FPGA’s speed, we can perform complex calculations in fractions of a second to calculate the plant response values consistently and accurately.

Figure 3. myRIO, Used for Calculating Plant Response

 

The NI platform has provided a stable and versatile development environment to support and supplement the development of a separate product. The adaptability of the myDAQ and myRIO platforms allowed them to simply be “plugged in” to the system with little modification and gave us the ability to rapidly build code and set up hardware for testing and data acquisition.

 

Figure 4. myRIO Integrated into Prototype System to Calculate Relationship Between the Control Signal Sent to an Actuator and the Resultant Accelerometer Response

 

Results

During testing, we recorded a reduction of up to 88 dB at 104 Hz for a single actuator, single accelerometer system. This almost completely removes any sensation of vibration from the test system. We measured this result with a myDAQ using plant response values calculated with a myRIO.

 

Conclusion

We at TBG Solutions adapted and implemented an active control algorithm on simple, low-cost hardware by using the stability, versatility, and rapid prototyping potential of LabVIEW, myDAQ, and myRIO. Next, we plan to expand the algorithm to use more actuators and sensors so we can use it to cancel vibration in systems with more complex dynamics. The scalability of LabVIEW VIs means that LabVIEW will continue to play a vital role in the continuation of this project.

 

Author Information:
Sam May
TBG Solutions
3A Midland Court, Barlborough Links, Chesterfield
Derbyshire S43 4UL
United Kingdom
Tel: +44 (0) 1246 819 100
samuel.may@tbg-solutions.com

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