Atheltic Helmet

MECH 2502 Final Project Proposal   Winter 2018

 

Group 20:  Anthony Reyes 214261341  Kuldeep Hujan 213585849  Liam Cope 214331052  Mahgoub Mohamed 214717235 

 

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Table of Contents    Summary of Proposed Project

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System Design

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Design Specification

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Bill Of Materials

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Project Planning and Management

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Appendix

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Figure Index  Figure 

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Table Index  Table 

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Summary of Proposed Project    The main goal of our system is to utilize accelerometers and thermistors to track the overall well being of athletes  in practice and in games. It is a known fact that athletes are at risk of injury when competing. The very act of  competing calls for the utmost effort. Strong effort with a physical game is a recipe for concussions. This is what  led our team to develop a means to help diagnose concussions with the use of accelerometers. Another risk  athletes are often exposed to is heatstroke. This is where the thermistors are used to track the athletes body  temperature.     Accelerometers are used to firstly measure acceleration. They can also be used to measure force. According to  Prof. Michael Gilchrist [1], both linear and angular acceleration are the culprits behind TBI’s. The accelerometers  will measure the motion of the athletes head and upon passing the threshold of acceleration a LED will be actuated  thus alerting coachs of a potential TBI.     The Thermistors work in a similar fashion. Measuring the the athletes body temperature and illumintating a LED  upon surpassing the threshold.      

Figure 1.0: ​In these pictures the black represents the accelerometers and the red represents the thermistor.1

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http://clipart-library.com/football-helmet-drawings.html 

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Rationale for the sensor selected as well as explanation of underlying physics of  the proposed sensor To better understand the choice of sensors we must look at the underlying principles of each sensors individually.   Firstly, the accelerometer is a tiny mechanical structure (MEMS) utilizing the principle of the capacitance[2]. When  the orientation of the accelerometer is changed the area surface area of the microscopic capacitor changes as well  resulting in a change in capacitance. This change in capacitance is then converted into useful voltages that the  DAQ will send to LabView. In LabView we plan to manipulate this data in a way that provides meaningful responses  from our system.   

Figure 2.0: ​Functional diagram of an accelerometer.2 

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​http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL193.pdf 

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Figure 3.0: ​Principle of capacitance within an accelerometer.3

Figure 4.0: ​Close up of an accelerometer and property diagram.4 Secondly, we have the thermistor. The thermistor works on the principle of resistance. We Know that the resistance  of an electrical component is linearly proportional to its temperature assuming first order approximation the  formula is . The thermistor is a highly thermal sensitive resistor. There are 2 types of thermistors,  NTC and PTC. The difference between these 2 types is how the resistance changes with temperature. NTC  3 4

​https://www.allaboutcircuits.com/textbook/reference/chpt-1/capacitor-sizing-equation/  ​http://www.mdpi.com/1424-8220/18/2/643 

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thermistors actually react in the opposite fashion, decreasing in resistance as temperature increases. The change  in resistance is converted to useful voltages and then send through the DAQ to our LabView program where it will  be manipulated to fulfill our needs. 

Figure 5.0: ​Picture of a thermistor.5  https://www.youtube.com/watch?v=E5YXyCBYEds&t=116s​ -Prof. Michael Gilchrist 

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​https://www.omega.ca/pptst_eng/HSTH-44000.html#description 

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System Design  

Figure 6.0:​ Functional block diagram that summaries the operations of the project.  

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The System starts off when the user experiences a sudden change in acceleration or their body temperature  changes. As described previously, our system is targeted toward athletic use. Many people experience preventable  injuries on the field, most of which are a result of sudden acceleration or overheating. The system illustrated in  Figure 7.0 is designed to carter to this need.     The system takes input from the user via two different sources of data measurement devices; an accelerometer  and thermistor. The accelerometers are attached to the helmet in such a manner that they provide data in all 3  axis. The thermistor then takes the temperature of the user. All data gathered from these 4 inputs are transmitted  to a data filtering component to weed out any unnecessary signals which may provide inaccuracies. It is vital that  these inaccuracies are taken out effectively as they can be detrimental to the performance of a game if the sensors  indicate false alarms.    After the signal has been conditioned, it it then transferred to a signal amplifier such that the incoming signal is up  to par with the requirements of the DAQ. After ample amplification, the signal is directed to the DAQ which  conditions the data and converts all necessary signals from analog to digital. The DAQ is a devices which makes it  possible for a computer to be involved in the process of data management.     In a virtual environment such as LabView, sensors can be integrated within the code. LabView makes it possible to  direct command based on sensor measurements. In the case of this project, labView broadly cover the following  functions:    1. Triangulate and compute the total acceleration and it’s direction.  2. Take inputs for all 3 accelerometers and thermistor and save it into an array for analysis later on.  3. Create a condition where if the acceleration or temperature readings go beyond a certain threshold, their  respective LEDs would be turned ON to indicate that the user’s health may be at risk.   

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Design Specification   a) Detail specification of each system component in full detail (e.g., calculation of resistor/capacitor values and cut off frequency for filters, calculation of gain for amplifiers, calculation of Nyquist frequency, layout of circuits,…). Our system involves the spring loaded rotating arm from the lab. On this arm we will be mounting a mock helmet where our sensors will be located. The idea is to change the springs to offer a certain aceration upon releasing the tension. This acceleration will be used to calculate force when struck against the wall. The famous equations F = ma allows us to make this conversion. The use of accelerometers will ensure we collect accurate accelerations for this calculation. The SEN-09332 accelerometer as a range of +- 250 g’s. This is a more than sufficient range. The interface in this sensor is analog so we will need to convert our signals to digital. The sensitivity is 8mV/ g. This useful voltage will manipulated in labview. We need a voltage supply of 3.5 - 6V To see the layout of accelerometers See Fig 1 The thermistor has the same specifications as the accelerometer but no conversion is needed to be made to meet the required need of Our system. The range of the voltage entering our system is about 3.5 - 6.5V from the voltage supply but after the sensor stage we expected the range of voltage to be between 0 - 5 V which is the voltage output from both the sensors were using. This voltage is them amplified 0 - 10 V to meet the required input voltage of of the DAQ. The expected sensitivity of our system is solely based on the sensitivity of our sensors and their offset but based on the specs of our sensores the sensitivity should be about 8mV/g.

 

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  Bill Of Materials  Part Name 

Part Number 

Quantity 

Needs to be  Purchased?   

Accelerometer Sensor  1-Axis 

SEN-09332  

3 

No 

Thermistor 

HSTH-44033-40  

1 

No 

Helmet 

N/A 

1 

Yes, $20.99  https://www.amazon.com /JBM-Ventilation-Multi-sp orts-Skateboarding-Roller blading/dp/B01HNYZNXY /ref=sr_1_5?ie=UTF8&qid =1520048174&sr=8-5& keywords=helmet 

Adjustable Power Supply 

TENMA 72-8335A  

1 

No 

DAQ 

Q8-USB  

1 

No 

  Table 1.0:​ Material needed for this project       

   

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Project Planning and Management Event Name 

Start Date 

End Date 

Assigned To 

Duration 

In-lecture workshop  02/13/18  session 

02/13/18 

All Members 

1 d 

Work on Video  Pitch and submit 

02/17/18 

02/18/18 

All members 

2 d 

Group Proposal 

03/01/18 

03/03/18 

All members 

3 d 

In-lecture feedback  03/06/18  session 

03/06/18 

All members 

1 d 

Reflect on Feedback  03/07/18  and implement  changes and  updates to design 

03/10/2018 

All members 

4 d 

Complete Labview  Program 

03/11/18 

03/18/18 

Mahgoub  Liam 

7 d 

Complete Helmet  Circuit 

03/11/18 

03/18/18 

Anthony  Kuldeep 

7 d 

Testing and Finalize  03/19/18  Design 

04/02/18 

All members 

15 d 

Preparation for  Presentation 

04/03/18 

04/03/18 

All members 

1 d 

Presentation in a  conference/fair  style to a judge  panel 

04/04/18 

04/04/18 

All members 

1 d 

Submit Final Group  Poster 

03/28/18 

04/05/18 

Anthony  Liam 

9 d 

Submit Final Group  Video 

04/01/18 

04/05/18 

All members 

1 d 

Peer Evaluation 

04/05/18 

04/05/18 

All members 

1 d 

Table 2.0:​ Project timeline  

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Figure 7.0: ​Gantt chart perspective of the entire project timeline. 

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Appendix  Accelerometer Specifications [2]

 

Figure 8.0  https://www.digikey.ca/product-detail/en/sparkfun-electronics/SEN-09332/1568-1043-ND/5140808 

Figure 9.0  https://www.digikey.ca/product-detail/en/sparkfun-electronics/SEN-09332/1568-1043-ND/5140808  Thermistor Specifications [4] 

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Figure 10.0  Tip Size - (2.3 - 2.5)mm   ​Adjustable Power Supply Specifications [5] 

· Figure 11.0 

 

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Amplifier Specifications [6] 

Figure 12.0  Q8-USB DAQ Specifications      System requirements  Board dimensions (L x W x H)  Analog inputs  Number of channels  Resolution  Input range  Conversion time  Input impedance  Maximum full scale range (FSR) error 

 

Type A USB 2.0 connector (USB 2.0 driver is required)  22.8 cm x 16.8 cm x 3.4 cm     8  16-bit  ± 5V, ± 10 V  4 µs¹  1 MΩ  ± 12 LSB, ± 6 LSB 

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Analog outputs  Number of channels  Resolution  Output range 

Slew rate  Conversion time  DC output impedance  Short-circuit current clamp  Maximum capacity load stability  Non-linearity  Maximum full scale range (FSR) error  Maximum load for specified performance  Digital inputs  Number of digital I/O lines  Input low / high  Input leakage current  Digital outputs  Number of digital I/O lines  Output low / high  Maximum drive current  Encoder inputs  Number of encoder inputs  Input low / high  Input leakage current  Maximum A and B frequency in quadrature  Maximum count frequency in 4x quadrature  PWM outputs  Number of PWM outputs  Output low (max) / high (min)  Minimum frequency  Maximum frequency  Bits resolution 

   8  16-bit  ± 10.8 V, ± 10 V  ± 5 V, 10.8 V  10 V, 5 V  3.5 V/µs  10 µs¹  0.5 Ω  20 mA  4000 pF  ± 1 LSB  ± 65 LSB  2 kΩ     8  1.5 V / 3.5 V  ± 2 µA     8  0.55 V / 4.50 V  ± 32 mA     8  1.5 V / 3.5 V  +/- 2 µA  24.883 MHz  99.532 MHz     8²  0.55 V / 4.50 V  23.7309 Hz  49.766 MHz  16 bits     

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            Referernces  

  [1] ​https://www.youtube.com/watch?v=E5YXyCBYEds&t=116s  [2] ​https://www.digikey.ca/product-detail/en/sparkfun-electronics/SEN-09332/1568-1043-ND/5140808    [3] ​http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL193.pdf  https://www.youtube.com/watch?v=i2U49usFo10   [4] ​https://www.omega.com/temperature/pdf/HSTH-44000.pdf  [5]   http://www.farnell.com/datasheets/2257000.pdf?_ga=2.86462160.934275953.1520059054-1478027156.15 20059054  [6]  https://moodle.yorku.ca/moodle/pluginfile.php/3212545/mod_resource/content/1/VoltPAQ-X1%20-%20User% 20Manual.pdf  [7]  https://moodle.yorku.ca/moodle/pluginfile.php/3212551/mod_resource/content/1/Q8-USB%20User%20Manual. pdf