Data Provided by the SmartWheel

The SmartWheel provides an automatically generated report following each session. The beginning and end of a session may be determined by elapsed time (e.g., 10 second trial), distance covered (e.g., 10 meters), or context of testing (e.g., the completion of a Figure 8 course). Each automatically generated report includes the following data:

General Session Data

Measure Definition
Time [s] The total elapsed time of the session.
Distance [m] The total distance traveled by the wheelchair during the session.
Average Speed [m/s] The average speed of the wheelchair over the entire session.
Highest Speed [m/s] The highest speed achieved by the wheelchair over the entire session.
Number of Pushes The number of complete pushes on the handrim detected by the SmartWheel over the entire session.

Session Results - Steady State

(These are averages calculated from all pushes except for the first 3.)

Measure Definition
Peak Force [N] For each steady-state push (all pushes in the session except for the first three), the peak force is measured. This is average peak force of all the steady-state pushes. (Note: This force is the total force applied.)
Peak Backwards Force [N] For each steady-state push (all pushes in the session except for the first three), the peak backwards force is measured. This is average peak backwards force of all the steady-state pushes. This shows the extent to which the client is unintentionally braking the wheelchair with every push. This parameter is only valid when the Subject is not actually trying to brake. (Note: This force is a tangential force.)
Speed [m/s] This is the average speed of the SmartWheel during steady state (the time after the first 3 pushes.)
Off-Rim Acceleration [m/s/s] This is the acceleration (will be negative) experienced by the SmartWheel when the Subject is not actively pushing, i.e. how fast the SmartWheel slows down when not being pushed. This parameter should only be used when the Subject is on a level surface, goes in a straight line, and pushes are symmetrical. Turning of the Wheelchair of any kind will invalidate this parameter.
Speed/Push-Frequency Ratio [m] This ratio is the average steady-state speed divided by the average steady-state push frequency. It provides an indication of how many pushes per second are being used to achieve the average speed.
Push Length [deg] This is the average length of the Subject's push, in degrees.
Push Frequency [1/s] This is how many times per second, on average, the Subject pushes on the SmartWheel.
Peak/Average Force Ratio This is the ratio between the peak force during a push, and the average force during a push. It is averaged across all steady-state pushes. It provides an indication of how smoothly pushes are applied to the SmartWheel's handrim. A lower ratio indicates the peak force is more close to the average force, which can indicate a smoother push.
Average Push Force [N] This is the average force the Subject applies to the SmartWheel handrim, averaged over all steady-state pushes.
Push Mechanical Effectiveness [%] This indicates the approximate percentage of applied force which is directed such that the wheelchair is accelerated. For example, if much of the applied force is down or outward, this value will be lower, because pushing inwards toward the hub, or pushing outward, do not actually make the wheelchair accelerate. This parameter is intended to provide a red flag for abnormally inefficient pushing.

Session Results - Startup

(These are calculated from the first 3 pushes.)

Measure Definition
Peak Force Push 1 [N] This is the peak force the Subject applied to the SmartWheel handrim during the first push. (Note: This force is the total force applied.)
Peak Force Push 2 [N] This is the peak force the Subject applied to the SmartWheel handrim during the second push. (Note: This force is the total force applied.)
Peak Force Push 3 [N] This is the peak force the Subject applied to the SmartWheel handrim during the third push. (Note: This force is the total force applied.)
Distance after 2nd Push [m] This is the distance covered by the SmartWheel during the first two pushes.
Distance After 3rd Push [m] This is the distance covered by the SmartWheel during the first three pushes.
Speed After 2nd Push [m/s] This is the speed that was achieved after the 2nd push.

Where is Your SmartWheel Data?

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