The red light is on the bag and the white light is on the body.
Results with only one spring! 
I only used one spring this time and the same weight.
I calculated for one spring, but was using two so I think that’s what was messing everything up in the initial experiments.
Dustyn’s colleagues who were critics at our midterm presentations said I should experiment withsprings and damping.
Here is the American Society of Biomechanics Submission about my midterm:
Everyone else’s work
“locked” backpack strategies:
* compression
* wide straps
* strap placement (shoulder, waist, harness systems)
Results –
The average weight of subjects’ bags was 11.45 pounds, and 10.35 pounds on average for women’s bags only.
Extension springs were chosen.
measured objects to ensure they are the average bag weight.
I put these inside a bag which weighs almost nothing, made of superlightweight and strong Dyneema.
Setup Ideas
Initially I was thinking of either trying to suspend the bag from a frame, similar to Larry Rome, but ideally more minimal
OR
to suspend the bag by replacing part of the straps with springs.
I got the load attached to the springs and a rod.
I also set up a frame structure prototype that can fit on my back (the mannequin is the size of my torso).
First I tried the rod alone, holding it up, but the load kept swinging horizontally and hitting my back. Then I added some extra rods to create more distance from my back, but of course the load was still swinging horizontally. I needed to stabilize the horizontal motion as much as possible. Right now I am doing that my introducing a plate, similar to Larry Rome (see illustration below). However, the Larry Rome/ Lightning Packs setup is quite clunky so ideally I would like to minimize this design and get rid of as much bulky-ness as possible while still using springs to suspend the load to reduce vertical movement and hence vertical force while also restraining horizontal movement.
Initial Light Paths
Springs were not working because I accidentally used two when I had calculated for one to be used.
I used a long exposure to show the motion with a light path coming from a marker in a person’s hip and on a bouncing mass.
I read Born to Run over the weekend.
Many of the subjects were new to me:
“let us live so when we come to die, even the undertaker will be sorry.”- mark twain;
Ultrarunning & Don Allison’s UltraRunning magazine;
Trail Running as fastest growing U.S. outdoor sport by 2002;
Tarahumara/Raramuri’s love of running (“you can’t pay someone to run with such infectious joy”, having fun, smiles, laughter while running difficult terrain) & athleticism/ “high state of physical conditioning”/ “didn’t hit the ground so much as caress it”;
rarajipari/ game of life;
Micah True/ Caballo Blanco;
Leadville, Ann Trason & “You’re tougher than you think you are”;
racing & running as uniting bonds of friendship;
Joe Vigil’s knowledge of running’s old masters, performance physiology/ science (leverage, propulsion, timing, living lean/ “eat as though you are a poor person”), character;
Emil Zapotek & his playfulness, enthusiasm, friendliness, love of life;
Matt Carpenter’s tests and shoe hacks (belt sanding & shaving soles, plunging in and out of water to test water retention & drying time);
Scott Jurek & his character (wrap himself in a sleeping bag and stand vigil by the finish line, cheering, letting the last persistent runner know he wasn’t alone) & meatless/ vegan diets of traditional endurance athletes (high quality nutrients, maximum nutrition with the lowest possible number of calories so his body isn’t forced to carry or process any useless bulk),
Jenn & Billy & “When running stopped being as fun as surfing, they agreed, they’d quit.”
Eric Orton: tearing endurance sports down to their integral movements and transferable skills. “Whenever you run, remember that feeling of straining against the rope. It’ll keep your feet under your body, your hips driving straight ahead, and your heels out of the picture. You can’t run uphill powerfully with poor biomechanics. Speed means less time on your feet.”
distance running is the world’s #1 participation sport
apprentice myself to Ken Mierke an exercise physiologist: “Quick, light leg contractions are more economical than big, forceful ones.”
To look at these mountains is a soul inspiring sensation; but to travel over them is exhaustive to muscle and patience.”
Emotional and sensual relationship to running: “We run when we’re scared, we run when we’re ecstatic, we run away from our problems and run around for a good time.”
Biomechanics learnings:
Morphology
Humans are the only running biped that’s tailless. What we don’t share with chimpansees, our closest living relative that is a walking animal: Achilles tendon which connects calf to heel, Arched feet, Short & straight toes, hefty butt which tightens as you run to prevent upper body momentum from flipping you on your face, tendon behind the head (nuchal ligament) which stabilizes head while animal moves fast.
Maybe human running was about going far, not fast.
Springy tendons (like rubber bands) store and return energy, to maximize endurance.
Though the horse and David were moving at the same speed, David’s legs moved more slowly. Meaning David covered more distance per step, and is more efficient.
Only mammals shed most of our heat by sweating.
-Dr. Dennis Bramble
Impact Loads:
“Athletes whose sport involves running put enormous strain on their legs. Each footfall hits one of their legs with a force equal to more than twice their body weight.” – Sports Injury Bulletin
“the most biomechanically efficient way to hold a waterbottle is in your armpit.
Barefoot Ted & Barefoot Ken Bob & “Shoes block pain, not impact!”
“innovations in motion control and cushioning don’t seem to defeat the ailments” – Irene Davis
cushioning does not reduce impact. E.C. Frederick 1986 Nike Sports Research Lab found “no difference in impact in soft versus hard shoes. Propulsive peak in the vertical ground reaction force was higher with soft shoes.”
With soft surfaces, people slap down hard to ensure stability and balance. “When you run in cushioned shoes, your feet are pushing through the soles in search of a hard, stable platform.”
As muscles in my feet got stronger, my arch got higher. Foot arch is the greatest weight bearing design ever created; it gets stronger under stress, the harder you push down, the tighter its parts mesh. Kenyan runners have wonderful elasticity in their feet. – Dr. Gerard Hartmann
Before the invention of the cushioned shoe, runners had nearly identical form: backs straight, knees bent, feet scratching, shock absorption from leg compression. (Fred Wilt’s 1959 book How They Train)
Heel was needed only for standing, not motion. – Biomedical Designer Van Phillips
Daniel Lieberman’s biological anthropology & “running shoes make our feet weak” ;
You support an area, it gets weaker. Use it extensively, it gets stronger.- Arthur Lydiard
“Your body needs to be shocked to become resilient. Surprise it with new challenges and nerves and ancillary muscles are suddenly electrified into action” – Eric Orton
Dr. Craig Richards’ challenge: “Is any running shoe company prepared to claim that wearing their distance running shoes will decrease your risk of suffering musculoskeletal running injuries? Is any shoe manufacturer prepared to claim that wearing their running shoes will improve your distance running performance? If you are prepared to make these claims, where is your peer – reviewed data to back it up?”
Stanford’s Vin Lananna & “send me my cheap shoes”
Nike:
Bowerman’s original mission of making an honest shoe. “Every great cause begins as a movement, becomes a business, and turns into a racket.”
Jeff Pisciotta Sports Research Lab: gather film of every existing barefoot culture, found more distribution of pressure
I am very eager to re-try vivo barefoot and to make myself some raremuri inspired sandals, as I have been meaning to do since last summer.
My goal
To make a backpack that is as positive for your back as possible, that hurts your back as little as possible.
I am working on preparing an abstract for my midterm and for the ASB submission.
So far, I have done preliminary research, written a draft of the abstract, calculated spring constant, ordered springs with that spring constant, and requested samples of other spring-y materials (materials with high rebound) such as foams.
Survey Results
Bag weight measurements from 80 ITP people on Friday February 24 2012
Graph of both ITP women and men bag weights
in weight amount order
in weight amount order, with women as first “mountain” of values, and then men as second “mountain” of values/ columns
average: 11.47 pounds
ITP women bag weight measurements
average: 10.35 pounds
max: 24.5 — Note: Women with the heaviest loads had multiple bags.
ITP men bag weight measurements
average: 13.1
max: 33 — Ryan had the most heavy belongings because his bag was 17 pounds and he was also carrying a 16 pound guitar.
I am more interested in making a comfortable backpack that eases fatigue.
This Week’s Assignment:
Visualization of FitBit data assignment
I wore our FitBit this week and input my food intake data into FitBit software.
* Definitions needed to understand calories burned figure:
FitBit Graphs made during last week’s class
I used the FitBit end of day 2/7, and all day 2/8 and 2/9.
I had the max movement on 2/8. I am interested to try it this upcoming week and also try to sleep with it to see how it tracks sleep and to see the data from days when I run around NYC.
Future FitBit explorations
I would like to use the FitBit better to gather more data points. Some of my sleep tracking did not register this week so I would like to improve sleep tracking as well as use the iPhone app to more accurately manually log activities, and food and water intake (most recommendations are at least 8-9 8oz glasses per day). Note: Manually logged activities replace the Tracker’s calorie estimate for that time frame.
Some specific test and data visualization ideas for future weeks:
Do I slept more consistently after drinking more water or on days when I’m more active? (Might find that insight by graphing on different axis.)
How does my FitBit performance change if:
– I am more consistently active throughout day?
– depending on different loads I carry or shoes I wear? (For example, running shoes versus fancy shoes.)
– depending on music I listen to? (Study inspired by Musicophilia by Oliver Sacks)
It would also be interesting to visualize FitBit data from people with different conditions such as patients with scar tissue or senior citizens.
+ Question for Dustyn:
Can we get FitBit Premium Access?
I think the extra data visualization and “trainer” guidance would be interesting to test over the rest of the semester.
Other measurement tools:
” If you’re a hardcore runner, biker, luger, or anything else, this is probably not the best device. A sports watch with GPS and heart-rate monitor would be far superior.” – TechCrunch
Challenge questions: what is your average stride length? How many calories do you burn per stride?
Response to “Biomechanical Energy Harvesting: Generating Electricity During Walking with Minimal User Effort”
I want to better understand the biomechanics and physics behind these ideas of how to measure load carrying, muscle work, and energy harvesting. These ideas of idea of negative and positive muscle work and metabolic costs seem potentially useful to me when I am trying to reduce the impact of bag loads on the body.
I wonder: How does low cost of harvesting of the spring-loaded backpack compare to the knee-mounted energy harvester?
Energy harvesting via human power. Limitation: focus attention on power generation at the expense of other activities.
Economical energy harvesting. Harvest energy from everyday activities.
I want to start to think about my Midterm project.
Design a system to track, measure, or visualize some spatial or temporal element of gait using anything from simple FSRs in a shoe to Kinect motion tracking.
- Option 1: Functional prototype and demonstration (documentation: blog post)
means can work in a demo in class
- Option 2: Paper prototype (documentation: Report research in the form of a draft of a publication quality paper (to be continued for final). This version will have the introduction and methods, while results and discussion will be left for the final)
you have physical element, but it could be cardboard and tape- doesn’t necessary workmore about specifics of why i need to do itunderlying concepts of energy consumptionmore research-yintroduction, methods-“Look up research by Pandolf in the 70’s (and maybe 80’s) he did for the Army. He did a lot of work measuring the metabolic cost of carrying different weight backpacks for soldiers, and made predictive equations. I’m not sure what aspects you want to test about your bags and shoes, but maybe you could use something like kinect to track the movement of wearers of the bags with different weights in them. I think by default we lean forward to accommodate heavy backpack loads, but maybe good backpack design could minimize this? You could test something similar with shoes – do insoles with a heel wedge make you walk with different back angles at different loads? You could also put several force sensing resistors on the bottom of the insole and track the pressure distribution across the foot while carrying different loads.
So, there are clearly a lot of ways to go here, so I think the first step is reading some of Pandolf’s stuff and deciding on some sort of question you are interested in answering to evaluate different bags and/or shoes.”
– Dustyn
Assignment
“Choose at least one joint and at least one plane of motion, and map the range of motion in some sort of digital or physical representation”
My Project
I will map the range of motion of various parts of the back,
such as rotation about the Y axis (forward or backward at the waist) or X axis (bend to the side) of the body.
Back Range of Motion while sitting
Coronal Plane Back Range of Motion
Sagittal Plane Back Range of Motion
Back Range of Motion in Coronal + Sagittal Planes for Sample Group
Video of Spine Flex in Sagittal Plane:
Seated spine flex analysis:
“A new approach for the kinematic analysis of sitting posture. The results can be applied to the improvement of biomechanical models of seated posture… Describes trunk movement in sitting posture by means of the instantaneous axis of rotation. The IAR is the axis around which a rigid body turns at every instant. In order to fit he movement of two bodies (the back and backrest [or bag]) , it is necessary for the corresponding IAR to coincide.”
– Ergonomics. 2009 Jun;52(6):695-706. Kinematics of the trunk in sitting posture: an analysis based on the instantaneous axis of rotation. Page A, de Rosario H, Mata V, Porcar R, Solaz J, Such MJ.Departamento de Física Aplicada, Universidad Politécnica de Valencia, Valencia, Spain. afpage@ibv.upv.es
Back Range of Motion while standing
More Quantitative Information:
Measurement Methods to test in the future:
“A new approach for the kinematic analysis of sitting posture. The results can be applied to the improvement of biomechanical models of seated posture.”
– Ergonomics. 2009 Jun;52(6):695-706. Kinematics of the trunk in sitting posture: an analysis based on the instantaneous axis of rotation. Page A, de Rosario H, Mata V, Porcar R, Solaz J, Such MJ.Departamento de Física Aplicada, Universidad Politécnica de Valencia, Valencia, Spain. afpage@ibv.upv.es
– Stinton, Shaun Kevin, “DEVELOPMENT, VALIDATION, AND APPLICATION OF A NONINVASIVE SPINAL MOTION MEASUREMENT SYSTEM” (2011). Doctoral Dissertations. Paper 169. http://uknowledge.uky.edu/gradschool_diss/169
Biomechanics Inspirational People
I am very interested in using biomechanics to improve design for the body.
In the past few years, my favorite examples of combining biomechanics and apparel improvement are:
1. Larry Rome & Suspension Load Backpack, now called Lightning Packs
This is one of the few proven innovations in backpack and bag designs intended to carry loads while moving. I have studied this project, but do not totally understand the physics/ science behind how it operates.
“Bungee cords to suspend the load from a backpack frame reduces not only its vertical movement, and hence its vertical force on the carrier, but also the energetic cost of walking with the pack. This permits larger loads to be carried while moving rapidly, and at the same time reduces the risk of orthopaedic and muscular injury.”
Rome, L. C., Flynn, L., Goldman, E., Yoo, T. Generating electricity from normal human movement. Science, 2005, 309:1725-1728.
Rome, L. C., Flynn, L.,Yoo, T. Rubber bands reduce the cost of carrying loads. Nature, 2006, 444:1023-1024.
“Because of his expertise in fish muscle and fish swimming, and the Navy’s long-term desire to build submersible vehicles which maneuver like fish, Dr. Rome was already in discussions with the Office of Naval Research when in late 2002 they made an unusual request: could he come up with a way to generate electricity from normal human movement? This lay outside of his usual research area, yet the problem was compelling–Special Forces in Afghanistan had to carry twenty pounds of batteries in addition to their 80 lb backpacks to power their GPS, communication equipment and night vision devices, and so generating electricity could greatly reduce this burden. Dr Rome invented the Electricity-generating Suspended-Load Backpack which can generate 1000-fold greater electricity than previous devices (20-40 Watts compared to 20 milliwatts). In Rome’s backpack, the load is suspended by springs, and as one walks the load moves up and down with respect to the frame. This movement is used to turn the generator and produce electrical power.
While doing this study Rome observed that this movement also provides an added ergonomic benefit: it reduces the peak forces on the body. If one wears a 50-lb backpack, the static force exerted on the body is equal to 50 lbs, however during walking or running the peak vertical forces acting on the body increase due to the necessary vertical acceleration of the added mass. During fast walking, the peak increases by 70% (e.g., to 85 lb); and during running, it triples to a 150 lbs (Fig 2). Rome invented the Suspended-load ergonomic backpack which greatly reduces the vertical movement of the load with respect to the ground. This in turn reduces the accelerative forces on the body by 82% during walking and 86% during running (Fig 2). Reducing accelerative forces reduces metabolic cost by 40 Watts and increased endurance, or alternately, it permits the carriage of 12 extra lbs for the same metabolic cost (i.e., for free.). Further, it permits running with heavy loads while avoiding orthopedic injury. This ability, as well as electricity-generation, are crucial in many military, emergency/disaster relief and humanitarian missions.
Four US patents have been issued and foreign patents are pending. The development and commercialization of the packs has been moved to a small company, Lightning Packs LLC.”
t0nnelabbiomechanics 