Tag Archives: sensors
By Tina Hilding, Voiland College of Engineering & Architecture
With increasing concern about concussions from sports, some players have started wearing electronic sensors to measure head impacts.
But a new study by Washington State University researchers has found that some of the sensors for non-helmeted sports are not fast enough to measure hard hits and don’t accurately measure what are thought to be the most serious, angular hits. They report on their work online in the journal Procedia Engineering (http://www.sciencedirect.com/science/article/pii/S1877705815014447).
“Concussions are a really challenging problem,’’ said Lloyd Smith, professor in the Voiland College’s School of Mechanical and Materials Engineering and director of WSU’s Sports Science Laboratory. “What we’re worried about is what’s going on with the brain, but we don’t have brain sensors that we can plug into. The closest thing is to see what is happening to the skull. That’s what these sensors are trying to do.
“The message is that you have to be careful with these sensors,” he said. “They may not work for every type of impact.’’
A ball is in the barrel of an air cannon before firing during testing in the lab.
The laboratory is the official baseball bat-testing facility for the NCAA and one of the premier labs in the nation for exploring the physics of bats, balls and, recently, the interplay of balls and the human head.
Most head-impact sensors have been developed within the past five years, and many college-level football teams have their players wear them. When a player receives a hard hit, the sensor records it and alerts trainers.
Researchers are also using data they’re collecting from the sensors to improve their understanding about sports-related head trauma. They have found that the helmeted sensors accurately measure hits.
Less commonly used are non-helmeted wireless sensors, which are affixed to headbands, mouth guards, adhesive patches or within an earpiece that the player can wear for sports like soccer, women’s lacrosse or softball.
In the study, the researchers attached the non-helmeted sensor to a head dummy. Using a pneumatic cannon, they fired lacrosse balls, soccer balls and softballs at it at different speeds. The researchers equipped the dummy with high-fidelity, wired accelerometers to collect data for comparison with feedback from the small, battery-powered sensor.
The researchers recorded 234 impacts, directing the balls at the dummy’s chin and forehead. Ball speeds were similar to those found in game conditions, although the softball was projected at speeds slower than seen in fast-pitch competition to avoid damaging the dummy. The soccer ball was only directed at the forehead.
The researchers found that the non-helmeted sensors aren’t able to accurately measure harder and faster hits, such as an impact from a hard-thrown softball. To measure the impact from a ball, the devices take a lot of measurements in rapid succession. The sensors were able to accurately see the hits from the softer, slower balls, but they couldn’t take data fast enough to keep up with the faster hits.
When the impact is harder, the sensor missed the peak acceleration, which would have the highest potential for causing a concussion.
“The harder the ball, the less correlation we found,’’ Smith said.
The researchers also found that the sensors did worse at measuring rotational than linear acceleration. Earlier work has found that most head injuries from sports come about from a hit that twists the head rather than a direct hit.
The researchers used a sensor with hardware specifications representative of most sensors of its kind. They are working with the sensor manufacturer and hope to do more studies that could lead to improvements. The manufacturer had no say in the study design or the interpretation of results.
“These sensors are one element in many ways to make sports safer,’’ said Smith. “I’m optimistic that people are taking these injuries more seriously, and I think it’s really encouraging in helping us better understand the effects and causes of concussions.’’
Opponents of a Maryland House of Delegates bill that would have led to sensors being affixed to helmets across the state have successfully defeated the bill before it could get out of subcommittee.
The bill would have reportedly required each county to select a high school, which would equip all football players’ helmets with sensors to alert athletic trainers if a hit was thought to be severe enough to cause a concussion.
The opposition included people like John Woolums, director of government relations for the Maryland Association of Boards of Education. He argued that attaching the sensors to helmets could impede helmet safety, by ensuring that they “no longer conform with safety standards.”
Brain Sentry CEO Greg Merril, whose company was prepared to install the sensors, disagreed with that contention.
Maryland Delegate Jon S. Cardin, who isa running for attorney general in that state, plans to introduce a bill creating a pilot program testing the efficacy of athletic helmet impact sensors for high school athletes.
Under the pilot program, each local school district will distribute impact sensors to a limited number of their high school athletes. The cost of the program and the impact sensors will be paid for by the sensor manufacturers in order to limit costs to school districts, according to Cardin.
In 2010, the Legislature passed a comprehensive concussion prevention program which included provisions that makes sure high school athletes cannot participate in sports while suffering from concussions or their debilitating symptoms. The problem now, according to Cardin, is that there are few objective measures for determining when an athlete has suffered a concussion which triggers the 2010 concussion law requiring him or her to be removed from the sporting event. Impact sensors bridge this gap by creating a reliable mechanism to show when an athlete has likely suffered a large impact to the head likely to cause a concussion.
“We are at a technological point where we can identify when a child has suffered a brain injury and should no longer be on the athletic field for their own safety,” said Cardin. “There are tremendous pressures on athletes and coaches to keep kids playing through injuries in the game that lead to long term and life altering consequences. Impact sensors remove these pressures and give us an objective way to measure brain injuries.”
According to Dr. David Rivara, Vice Chair of the Pediatrics Department at the University of Washington in Seattle, while there are often rules in effect requiring athletes with brain injuries to be removed from a game, “if children cover up injuries because they’ve been told that ‘you can’t let the team down’ or a parent or coach assumes a blow to the head is minor, this creates a dangerous ‘league of denial.’”
Greg Merril, CEO of Brain Sentry (http://brainsentry.com/), an impact sensor manufacturer located in Bethesda, Maryland said “Over the past 10 years research has provided significant insight into mild traumatic brain injury. We now know that it is critical to identify children that have suffered concussions so we can allow them to heal prior to returning to play. The biggest challenge is that concussions are very difficult to identify. Sensor technology is now available that can help detect unusually large impacts that may be experienced by children when they participate in sports. These sensors are extremely easy to use and are now very affordable. There is now no reason that this technology should not be required as standard equipment for helmeted sports.”
Cardin added: “I have heard too many stories of children suffering from concussions that can no longer play the sports they love and worse yet; their quality of life suffers as they are forced to spend hours in dark rooms because too much light gives them headaches. We have the technology to protect young athletes, and I think it is about time we step up to the plate and do so.”