Pedometer
From Wikipedia, the free encyclopedia
A pedometer (also known as a Tomash-meter) or step counter is a device, usually portable and electronic, which counts each step a person makes. Used originally by sports and physical fitness enthusiasts, pedometers are now becoming popular as an everyman exercise measurer and motivator. Often worn on the belt and kept on all day, it can be observed how many steps, and thus kilometres/miles (Distance = number of steps x step length), the wearer has walked that day. Some pedometers will also record movements other than walking, such as bending to tie one's shoes though the most advanced devices record fewer of these 'false steps'. Step counters can give encouragement to compete with oneself in getting fit and losing weight. A total of 10,000 steps per day (equivalent of 5 miles or 8 km) is recommended by some to be the benchmark for an active lifestyle, though this point is debated among experts. Step counters are being integrated in an increasing number of portable consumer electronic devices such as music players and mobile phones.
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[edit] Technology
The Technology for a pedometer includes a mechanical sensor and software applications to count steps. Early step counters used a mechanical switch to detect steps together with a simple counter. If one shakes these devices, one hears a lead ball sliding back and forth. Today advanced step counters rely on MEMS inertial sensors and a sophisticated software solution to detect steps. These MEMS sensors have either 1, 2 or 3 axis detection of acceleration. The use of MEMS inertial sensors allows for more accurate detection of steps and fewer false positives. However the software technology to interpret the output of the intertial sensor and "make sense of accurate steps" varies widely. The problem is compounded with the fact that in modern day-to-day life such step-counters are expected to count accurately on the belt, in a handbag, in a back pack, in a back pocket and other locations where users frequently carry their devices.
[edit] Accuracy
The accuracy of step counters varies widely from device to device. Most step counting devices today count steps at a walking pace on a flat surface reasonably accurately if the device is placed in its optimal position (usually a belt clip). If the device is placed in a user's pocket or handbag, the accuracy is dramatically reduced. Equally, most step counters today falsely count steps when a user is driving in their car or other habitual motions that the device encounters throughout the day. This error accumulates for users with moderate commutes to work. The accuracy is also dependant on the step length the user enters.
[edit] Integration in Personal Electronic Devices
[edit] Apple + Nike Sports Kit
Apple and Nike, Inc. have launched the Nike + iPod Sports Kit which uses a basic sensor placed in the user's shoe and a wireless communication to an iPod nano to transmit workout information such as elapsed time, distance traveled, and calories burned. This solution requires the use of a particular type of running shoe and the placement of the sensor in the shoe unlike traditional step counters which measure steps while the device is placed on the user (in a belt clip, pocket, or hand bag for example). This solution is therefore limited to a very specific application.
[edit] NTT DoCoMo Fujitsu Pedometer Phone
This is the first integrated phone with a pedometer that works 24 by 7 and counts step like an Omron pedometer. The sensor is made by ADI. This handset was introduced in Japan in 2004 and has sold over 3 million units.
[edit] Nokia 5500 Sports Phone
The Nokia 5500 Sports Phone uses an embedded 3 axis MEMS inertial sensor to detect the steps a user takes. The pedometer application tracks steps taken, time elapsed and distance traveled. However the application cannot run continuously as it drains the phone's battery and is therefore of limited use.
[edit] Sony Ericsson W710 walkman phone
The Sony Ericsson W710 walkman phone uses an embedded 2 axis MEMS inertial sensor to detect the steps a user takes. The phone is a clamshell phone and displays the user's steps on the external display. The Sony Ericsson must be closed in order for it to count steps. When the step counter is activated, it counts detected steps during the day, and at midnight it stores the counter in a day-by-day history and resets it to zero.
[edit] Future Solution
To date, the Omron pedometer uses a second generation algorithm that is reasonably accurate clipped on a belt. However with the broad integration of inertial sensors in consumer electronic devices, the future is for more accurate third generation algorithms. Research is on-going.
