Measuring work using elastic system

[Borelli]

I have built an apparatus that is intended to measure external work output. It consists of force transducer connected inline to latex elastic tubing stretch to ~twice it’ resting length (via three pulleys) connected to a linear variable differential transducer (to measure displacement) connect via non-elastic cord (very low strain) to a finger. (see figure attached)

1) Does this system seem like a reasonable method of measuring the external work output of the finger? If not please share your comments.

I wanted to check to see if the force measured at the force transducer was the same on both ends of the pulley system (I was nervous that reduced efficiency of the pulleys would cause a difference in the forces from one end of elastic band to the other end) .

2) Should the force indeed be the same at both ends of the elastic tubing?

3)Is it best to have the force transducer at the opposite end of the system than the finger to get the least amount of force variability.

4) If I include the force due to the mass of the LVDT rod, should the force exerted at the finger be the same as the force measured at the opposite end force transducer?

4) I noticed that when I displace the finger that the first pulley moves an angular distance of approximately 20 degrees but the last pulley (closest to the force transducer) does not move hardly at all. Is this alright or an indication that friction in the pulleys is dissipating the force. It seem to my naïve mind that it is o.k. because the elongation of the latex tubing is dispersed across the entire length of the elastic tubing and therefore the opposite end will move very little.

5) If you have any suggestions on how to best test this system (to ensure it is measuring what I want) or any changes to the design please reply.

Thank you for your help.

Daniel

 

[LightHero]

1) This system seems reasonable for measuring external work output of the finger. However, it is important to note that the accuracy of the system will depend on the quality of the force transducer and LVDT. 2) Yes, the force should indeed be the same at both ends of the elastic tubing, assuming an ideal system with no friction or energy losses. 3) It is best to have the force transducer at the opposite end of the system from the finger in order to minimize any variability due to friction in the pulleys. 4) If you include the force due to the mass of the LVDT rod, the force exerted at the finger should be equal to the force measured at the opposite end force transducer, plus the force due to the mass of the LVDT rod. 5) To test the system, you can measure the displacement of the finger and then the corresponding force at the force transducer. If the data from these two measurements match, then the system is measuring the work output accurately. Additionally, you can also check the accuracy of the system by testing it with an object of known mass and measuring the force due to gravity.

 

[astrokreng]

I would like to commend you on your well-designed apparatus for measuring external work output. The use of a force transducer and linear variable differential transducer (LVDT) is a reliable method for measuring force and displacement, respectively. However, I do have a few comments and suggestions for your apparatus:

1) Overall, your system appears to be a reasonable method for measuring external work output of the finger. However, it is important to consider the potential sources of error, such as friction in the pulleys and the effects of the mass of the LVDT rod, which could affect the accuracy of your measurements.

2) Ideally, the force should be the same at both ends of the elastic tubing, assuming there is no friction in the pulleys. However, it is important to test this and make any necessary adjustments to ensure the accuracy of your measurements.

3) It may be beneficial to have the force transducer at the opposite end of the system from the finger to minimize any variability in force due to the movement of the finger. This will also help to reduce any potential errors caused by the mass of the LVDT rod.

4) Including the force due to the mass of the LVDT rod in your measurements may affect the accuracy of your results. It may be best to measure the force exerted at the finger separately and subtract the force due to the mass of the LVDT rod from your overall measurements.

5) To ensure the accuracy and reliability of your system, it is important to conduct thorough testing and calibrations. This could include testing the system with known weights or forces to validate your measurements, as well as making any necessary adjustments to reduce sources of error.

Overall, your apparatus appears to be a well-designed and promising system for measuring external work output. I would suggest conducting further testing and making any necessary adjustments to ensure the accuracy and reliability of your measurements. Best of luck with your research.