Skiing Power

ski power

Overview

Power meter devices are currently being utilized in cyclic training. These devices are used professionally, allowing athletes to capitalize on defined power outputs to alter their training technique. This grants those athletes with the ability to gain optimal competitive performance. Recreational sportsmen can also use the device to gage their athletic execution, track caloric expenditure and other general fitness capabilities.

The Backcountry Ski Power Meter will introduce these capabilities into the winter sport of backcountry skiing. There is currently a lack of devices that utilize power readings for skiing applications. Allowing a preliminary introduction of a power gage into skiing will provide beneficial feedback from customers and users alike with different uses to further research and develop.

 

Phase I: Design Inputs

In Phase I  the group thoroughly went through the goals they were to achieve for the design and development of the project. Design inputs to achieve these goals were determined based on user needs, system requirements, hazard identification and other criteria. There was currently no similar design for a power meter used in winter sports. It was determined that skiers would be able to use such a device for training purposes.

Design specifications were determined to be essential to the product, including:

  • The device must withstand up to 400 pounds of force [lbf]
  • The device must fit within [3” x 8”] dimensions to avoid being intrusive to the athlete’s activity
  • All electronic parts must be protected in a water-tight enclosure due to winter environment
  • The device must provide visual feedback to user

In addition to these specifications, several levels of safety hazards were identified:

  • Minimal amount of injury to the intended user
  • Notable injury – physical over-exertion
  • Possible injury – distractions in the environment (long term)
  • Minor case – electrical shock

It was determined that utilizing strain measurements would be the most accurate and efficient method for determining desirable power values. Several locations on the configuration for attaining strain values were considered including the bottom of the ski boot, the bindings, and the ski itself.

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Fig 1: Concept Sketch With Strain Gauges Being Used Inside the Ski

 

Phase II: Design Outputs

Phase II involved developing the project design outputs with a product design being created and developing the manufacturing process.

Implanting the strain measuring device into the ski itself was concluded to be the most optimal location, as it protected the power meter from contact with water and would also be the simplest design to manufacture. The power meter itself uses an amplifying load cell to measure strain values. These values are then digitized using an Arduino microprocessors which then computes the relationship between power and strain:

P=Δx(E·ε)A/Δt [W]

An epoxy resin is applied in order to minimize water contact, and to ensure that all wiring remains intact during athletic activity.

 

Phase III: Verification and Validation

Phase III involved verifying and validating the design outputs determined in Phase II through testing and analysis.

A Proof of Concept was developed in order to determine feasibility of the design. This was accomplished by attaching strain gauges to a ski and measuring voltage output through a Wheatstone bridge and voltmeter. It was determined that the voltage readings did correlate to the strain put on the ski, however, the strain readings were incredibly small. It was decided that a load cell would be incorporated into the design instead of standard strain gauges to enhance the strain readings and simplify the design.

Fig 2: Testing Configuration

 

Phase IV: Introduction Into Manufacturing

In Phase IV,  all documentation, drawings, and design concepts were finalized in order to develop a finished product.

The power meter is installed into the ski by drilling a small, circular section into the top of the equipment. The load cell is placed into the section and sealed with a liquid resin to ensure that it is both stably adhered and to reduce water damage. The calibrated load cell is then wired to the microprocessor in front of the foot binding encased in a plastic, water-tight enclosure. Another enclosure has been added to protect the battery and LCD display screen used to read the power values obtained.

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Fig 3: Project Lead Jeffrey Stein Soldering Electronic Components

 

 

 

Fig 4: Calibration of Load Cell Microprocessor 

 

Final Prototype

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Fig 5: Finalized Prototype

The project succeeded in attaining a visual reading of power from a skier actions. The project fell short of attaining the desired goal of having a numerical output displayed and instead used LED’s to signify amount of power. This as due to the groups lack of coding skills. Future activities for this project include adding Bluetooth capability to transmit numerical results. Adding an accelerometer is another possible implementation that would provide more accurate design.  Most importantly however is rebuilding the design with smaller components to create a more compact and appealing design. This new design would be easier to seal against the elements in order to achieve a design capable of being tested and used in actual skiing applications.

Meet The Team

Jeff Stein

jeff

Hi, my name is Jeff. I am an outdoor enthusiast, competing competitively in cycling and previously as a member of the UNR Ski team in 2011. I enjoy researching material mechanics and furthering my knowledge in the field of engineering through practice and theory. Mainly practice.

Carlos Caro

carlosHello, I am Carlos. I’m a Reno local and enjoy hiking around the area. I am looking forward to entering the mechanical engineering job market in order to start my career.

Ashton Tafarrodi

ashton

I’m Ashton. I enjoy costuming and special effects that are used in films.  I hope to obtain a job in the film industry designing special effects equipment and props.

Megan Shalvis

megan

Hi, I’m Megan. I am passionate about helping disabled individuals improve their everyday life styles. I plan on using my degree to work with prosthetics in order to help other better their lives.

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