Posts tagged sports
CU research propels “Blade Runner” to Olympics
Jul 11th
Professors Rodger Kram and Alena Grabowski of the integrative physiology department have been involved in several studies analyzing the performance of amputee athletes, including Pistorius, who use blade-like, carbon fiber leg prostheses in track events. In 2007, Pistorius was barred from international competition by officials from the International Association of Athletics Federations, or IAAF, who ruled his Cheetah Flex-Foot leg prostheses conferred him an advantage over other runners.
Barred from competition, then exonerated
The decision was based in large part on a German study commissioned by the IAAF. However, data presented in April 2008 by a team that included Kram and Grabowski to the Court of Arbitration for Sport in Lausanne, Switzerland — an international group set up to settle disputes in sports — showed Pistorius gained no physiological advantage from the Cheetah prostheses over competitors. The team’s evidence and testimony played a key role in overturning the decision, allowing Pistorius to compete in able-bodied events.
“The methodology of the German study that involved measuring Oscar’s oxygen consumption while running was flawed,” said Kram, who has been measuring the oxygen consumption of runners since 1983. “When we had a chance to properly measure Oscar we found that while he is quite economical in oxygen consumption compared to your average Joe, his values are well within what would be expected for a high-caliber athlete.”
At the arbitration hearings in Switzerland, Kram also argued that if a prosthetic device provides a mechanical advantage, it would very likely provide an energetic or physiological advantage. “Since there is no energetic advantage, it infers that the prostheses do not provide a mechanical advantage either,” said Kram.
Another chance
Although Pistorius subsequently failed to make the 2008 Olympic team, he was selected by South Africa’s Olympic Committee last week to run in both the individual 400 meters and a leg of the 4×400 meter relay in the 2012 Olympic Games in London, which begin on July 27. “I was delighted that Oscar was selected,” said Kram. “I was sure he’d be named to the 4×400 meter relay, but being named to the 400-meter individual event was a surprise.”
Since 2008, the research team involving CU-Boulder has continued its studies. In a 2010 study led by Grabowski, researchers used force-measuring treadmills to analyze the biomechanics of unilateral amputees — those with one amputated leg — over a wide range of running speeds. The team found the force produced by the prosthetic, carbon fiber leg was 9 percent less than that of the unaffected leg. “Applying force to the ground is crucial in sprinting events,” said Grabowski.
“We inferred that running-specific prostheses impair force generation and likely limit top sprinting speed,” said Grabowski, who received her doctorate under Kram in 2008 and recently returned to CU-Boulder as a research faculty member after doing postdoctoral work at the Massachusetts Institute of Technology. Other authors on the 2010 paper included Kram, Craig McGowan of the University of Idaho, William McDermott of the Orthopedic Specialty Hospital in Murray, Utah, and Hugh Herr of MIT.
In a 2012 paper by the same group and led by McGowan, the leg stiffness of Paralympic sprinters with both unilateral and bilateral leg amputations was compared to non-amputee sprinters across a range of speeds. The team found leg stiffness remained constant or increased with speed in non-amputees but decreased in sprinting amputees.
“During running, the leg behaves much like a spring, and the stiffness of the leg greatly influences the overall mechanics of the runner,” said Grabowski. “The study indicates that the prosthetic device limits the ability of a sprinter to change their leg stiffness during running.” In the future, she said, researchers may be able to design a prosthetic device with “adaptive stiffness” that would more accurately emulate the mechanics of a biological ankle during sprinting.
Research fueled by veterans needs
Grabowski, whose work is funded by the Veterans Administration, is particularly interested in designing better prosthetic ankle devices for military veterans or those on active duty who have undergone amputations. In collaboration with the Denver Department of Veterans Affairs, Grabowski is beginning a research effort to further develop battery-powered ankle-foot prostheses for walking and running. Such prostheses have the potential to restore mobility to users similar to the mobility they had prior to amputation, she said.
The research team is interested in locating potential test subjects in the Denver-Boulder area with leg amputations to participate in lab studies. “CU-Boulder is actively pursuing research that aims to improve the lives of amputees, particularly veterans and current military personnel,” she said. Potential study candidates can contact Grabowski at Alena.Grabowski@colorado.edu.
Research in Kram’s Locomotion Laboratory on the CU-Boulder campus goes far beyond athletics. Collaborating faculty and students are targeting the energetic costs of walking, including uphill and downhill walking in older adults; the energetics of passive cycling to treat and prevent obesity and heart disease; and studies on animal locomotion, including kangaroos, tortoises and elephants.
For more information on the CU-Boulder Locomotion Laboratory visit http://www.colorado.edu/intphys/research/locomotion.html. For more information on CU’s integrative physiology department visithttp://www.colorado.edu/intphys/.
Tesla Motors’ Devastating Design Problem
Feb 23rd
FROM Understatement.com
By Michael Degusta
Tesla Motors’ lineup of all-electric vehicles — its existing Roadster, almost certainly its impending Model S, and possibly its future Model X — apparently suffer from a severe limitation that can largely destroy the value of the vehicle. If the battery is ever totally discharged, the owner is left with what Tesla describes as a “brick”: a completely immobile vehicle that cannot be started or even pushed down the street. The only known remedy is for the owner to pay Tesla approximately $40,000 to replace the entire battery. Unlike practically every other modern car problem, neither Tesla’s warranty nor typical car insurance policies provide any protection from this major financial loss. Here’s how it happens.
Despite this “brick” scenario having occurred several times already, Tesla has publicly downplayed the severity of battery depletion risk to both existing owners and future buyers. Privately though, Tesla has gone to great lengths to prevent this potentially brand-destroying incident from happening more often, including possibly engaging in GPS tracking of a vehicle without the owner’s knowledge. UPDATE!
NOTE (UPDATED!): The argument outlined in this story by Michael DeGusta that originally appeared on theunderstatement.com has been confirmed by Tesla with the following statement:
All automobiles require some level of owner care. For example, combustion vehicles require regular oil changes or the engine will be destroyed. Electric vehicles should be plugged in and charging when not in use for maximum performance. All batteries are subject to damage if the charge is kept at zero for long periods of time. However, Tesla avoids this problem in virtually all instances with numerous counter-measures. Tesla batteries can remain unplugged for weeks (even months), without reaching zero state of charge. Owners of Roadster 2.0 and all subsequent Tesla products can request that their vehicle alert Tesla if SOC falls to a low level. All Tesla vehicles emit various visual and audible warnings if the battery pack falls below 5 percent SOC. Tesla provides extensive maintenance recommendations as part of the customer experience.
— Ed.
How To Brick An Electric Car
A Tesla Roadster that is simply parked without being plugged in will eventually become a “brick”. The parasitic load from the car’s always-on subsystems continually drains the battery and if the battery’s charge is ever totally depleted, it is essentially destroyed. Complete discharge can happen even when the car is plugged in if it isn’t receiving sufficient current to charge, which can be caused by something as simple as using an extension cord. After battery death, the car is completely inoperable. At least in the case of the Tesla Roadster, it’s not even possible to enable tow mode, meaning the wheels will not turn and the vehicle cannot be pushed nor transported to a repair facility by traditional means.
The amount of time it takes an unplugged Tesla to die varies. Tesla’s Roadster Owners Manual [Full Zipped PDF] states that the battery should take approximately 11 weeks of inactivity to completely discharge [Page 5-2, Column 3: PDF]. However, that is from a full 100% charge. If the car has been driven first, say to be parked at an airport for a long trip, that time can be substantially reduced. If the car is driven to nearly its maximum range and then left unplugged, it could potentially “brick” in about one week.[1] Many other scenarios are possible: for example, the car becomes unplugged by accident, or is unwittingly plugged into an extension cord that is defective or too long.
When a Tesla battery does reach total discharge, it cannot be recovered and must be entirely replaced. Unlike a normal car battery, the best-case replacement cost of the Tesla battery is currently at least $32,000, not including labor and taxes that can add thousands more to the cost.
Five Examples And Counting
Of the approximately 2,200 Roadsters sold to date, a regional service manager for Tesla stated he was personally aware of at least five cases of Tesla Roadsters being “bricked” due to battery depletion. It is unknown if there are additional cases in other regions or countries.
The 340th Tesla Roadster produced went to a customer in Santa Barbara, California. In 2011, he took his Roadster out for a drive and then parked it in a temporary garage while his home was being renovated. Lacking a built-in Tesla charger or a convenient power outlet, he left the car unplugged. Six weeks later his car was dead. It took four men two hours to drag the 2,700-pound Roadster onto a flatbed truck so that it could be shipped to Tesla’s Los Angeles area service center, all at the owner’s expense. A service manager then informed him that “it’s a brick” and that the battery would cost approximately $40,000 to replace. He was further told that this was a special “friends and family” price, strongly implying that Tesla generally charges more.
As a second Roadster owner discovered, the Tesla battery system can completely discharge even when the vehicle is plugged in. This owner’s car was plugged into a 100-foot long extension cord for an extended period. The length of this extension cord evidently reduced the electric current to a level insufficient to charge the Tesla, resulting in another “bricked” Roadster.
A third bricked Tesla Roadster apparently sits in its owner’s garage in Newport Beach, California. That owner allegedly had a similar prior incident with a BMW-produced electric vehicle. He claimed BMW replaced that vehicle, but Tesla refuses to do the same. The owner either couldn’t afford or didn’t want to pay Tesla the $40,000 (or more) to fix his car.
A fourth customer shipped his Tesla Roadster to Japan, reportedly only to discover the voltages there were incompatible. By then, it was too late, the car was bricked, and he had to ship it back to the US for repairs.
The whereabouts and circumstances of the fifth bricked Roadster the Tesla service manager expressed knowledge of are unknown.
No Warranty, No Insurance, No Payment Plan
Tesla has a “bumper to bumper” warranty [Page 3: PDF], but the warranty text allows Tesla to hold the owner responsible for any damage related to “Failure to maintain the Battery at a proper charge level at all times” – the meaning of “proper charge” doesn’t appear to be specifically defined. Tesla CEO Elon Musk, Vice President of Sales & Ownership Experience George Blankenship, and Vice President of Worldwide Service J. Joost de Vries all became directly involved in at least one “brick” situation, with de Vries stating in writing that since Tesla’s documentation and warranty “identify in clear language to keep the Roadster on external power when parked” the decision to decline any warranty or financial relief was “correct and justified”.[2]
Unfortunately for current and future Tesla owners who encounter this problem, it’s also not covered by normal automobile insurance policies. This makes the situation almost unique in modern car-ownership: a $40,000 or more exposure that cannot be insured. After all, car insurance is designed to protect owners and drivers even when they are neglectful or at fault. The affected customers probably would have been in a better financial situation if they’d accidentally rolled their Teslas off a cliff, as insurance would generally cover much of those costs.
Due to Tesla batteries naturally decaying over time, Tesla offered Roadster customers a $12,000 “battery replacement program”. This program is intended to replace a Roadster battery with a new one seven years after purchase. When asked, the Tesla service manager said even if owners had paid in advance for this replacement battery program, they would not be allowed to use it to replace an accidentally discharged battery – they would have to pay the full $40,000-plus cost.[3]
The Santa Barbara owner was also informed that no other financing or payment plan would be made available to pay for the replacement battery, and that he needed to either pay in full or remove his dead vehicle from the Tesla service center as soon as possible.
Understated Warnings to Owners
With such a large price tag for a bricked vehicle, it would be reasonable to expect Tesla to go to great lengths to ensure their customers were fully aware of the severity of battery discharge. Instead it seems that Tesla, while working to make it clear their vehicles should always be left plugged in, also appears to have focused on trying not to spook their current and future customers about the potentially severe ramifications of complete battery discharge.
The Tesla Roadster Owners Manual begins with several “Important Notes About Your Vehicle” [Page 1-2: PDF], none of which make any mention of battery discharge. In Chapter 5 of the manual, where vehicle charging is addressed, Tesla states that the vehicle is “designed to be plugged in” and that allowing the charge level to fall to 0% “can permanently damage the Battery.” [Page 5-2: PDF] It does not specify that a completely discharged battery may need to be replaced, entirely at the owner’s expense, at a cost that could be the majority of the value of the vehicle.
Tesla did begin handing out a “Battery Reminder Card” [PDF] when a Roadster was brought in for servicing. However, the card gently and cheerfully prods owners to “Remember – a connected Roadster is a happy Roadster!” with no mention of the possible consequences of a complete discharge.
There is no warning regarding battery discharge on the actual power port of the vehicle itself, where a gas-powered car often contains warnings about issues like the use of leaded gasoline in an unleaded vehicle. There is also no warning on the power port or in the Roadster Owner’s manual regarding the use of extension cords.
for more on this story see understatement.com where it first appeared.