Walking Distance Measurement Systems

POSIFA Microsystems developed walking distance measurement systems as shown above. These systems can measure the distance for many walking ways to take including:

• Walk with your spouse, child, or friend
• Walk the dog
• Use the stairs instead of the elevator
• Park farther from the store
• Better yet, walk to the store
• Get up to change the channel
• Window shop
• Plan a walking meeting
• Walk over to visit a neighbor
• Walk around the garden or do a little weeding 

There are countless physical activities out there, but walking is a good form of exercise for many people. Knowing walking distance will help people develop an exercise program that's effective for losing weight, increasing aerobic fitness, and improving heart health.

Many efforts have been made to measure the distance traveled by humans for a long time. There are several ways to measure the distance moved by walking or running in daily life, some of which already use commercial products, but none of them is ideal and perfect.

As well know, one way is based on radio frequency, such as GPS, or may use optical-based systems, such as video tracking. Such systems are not available indoors and degrade significantly in deep city canyons.

As an alternative, the measurement can be made by self-contained tracking systems. Such systems use commercially available MEMS inertial sensors and magnetic sensors. However, the performance of MEMS accelerometers and angular rate sensors is limited by random noise and calibration error. When they are used in a position tracking systems, it becomes the source of unbounded growth in position error.

A new walking distance measurement system is developed by POSUFA Microsystems, which is based on their MEMS thermal flow sensors. Human walking exhibits variability from step to step. As above listed walking ways, all most each step may be different in walking direction or in step length. It is impossible to do correct and precise measurement using available distance measurement systems. Only the POSIFA systems can do that because it measures the distance simply by adding all step length together. 

Each human walking step consists of stance phase, swing phase, and stance phase again. In any stance phases the foot traveling velocity is zero. In the swing phase the foot traveling velocity increases from zero to maximum and then decreases from maximum to zero like a pendulum curve. The thermal flow sensor can be managed to measure any instantaneous velocity of a particular foot traveling step. Then the instantaneous velocity is integrated over the traveling time of the particular step to produce the length of the particular step. All the lengths of each traveling steps can be accumulated to provide the distance of this human walking event.

In such systems, the thermal flow sensor only measures the instantaneous velocity.  The measurement signals are sent to a smart phone using Wi-Fi communication. The Smart phones are useful in this application because they are portable and have sufficient computational power to compute and analyze the measurement signals to provide the walking distance and other information people are interested.