Table 1 Propulsion technique variables and their definitions, automatically processed from the wheel signals using custom written Matlab code [26]
Variable | Description | Equation |
|---|---|---|
Mechanical efficiency (%) | The percentage of internal power used for external power delivered at the wheels | Mean power output/Energy expenditure |
Push time (s) | Time from the start of positive torque to the stop of positive torque for an individual push. | tend(i) ‐ tstart(i) |
Cycle time (s) | Time from the start of positive torque to the next start of positive torque. | tend(i) ‐ tstart(i ‐ 1) |
Frequency (push*min−1) | The number of complete pushes per minute. | Npushes/Δt |
Work/push (J) | The power integrated over the Contact angle of the push. | ∑start : end(Tz * ΔØ) |
PnegS (W) | The minimum power preceding the push phase | Min<start(Power) |
PnegE (W) | The minimum power following the push phase | Min>end(Power) |
Contact angle (°) | Angle at the end of a push minus the angle at the start. | Øend(i) ‐ Østart(i) |
Ftotmean (N) | 3d mean force within the push phase | Meanstart : end(Fx2 + Fy2 + Fz2)0.5 |
Ftotpeak (N) | 3d peak force within the push phase | Maxstart : end(Fx2 + Fy2 + Fz2)0.5 |
FeFmean (%) | Mean Fraction effective Force | Meanstart : end(Ftangential/Ftotal) |
GH start position (mm) | Horizontal position of the glenohumeral joint (GHx) at the start of the push with respect to the wheel-axle (WAx) | GHxstart(i) ‐ WAxstart(i) |
GH displacement (mm) | The position difference between GH at the start and end of the push phase | GHend(i) ‐ GHstart(i) |