Table 1.

Propulsion variables

Variable:	Description:	Equation:
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) − tend(i − 1)
Contact angle (rad)	Angle at the end of a push minus the angle at the start.	Øend(i) − Østart(i)
Fpeak (N)	3d peak force during the push phase	Maxstart : end(Fx2 + Fy2 + Fz2)0.5
Mean Power/push (W)	The mean power during the push phase.	Meanstart : end(Tz • ΔØ)
Work/push (J)	The power integrated over the duration of the push.	∑start : end(Tz • ΔØ)
Frequency (push/min)	Pushes per minute.	Npushes/Δt
Mean power/minute (W)	The mean total (unilateral) power (Tz*Angular velocity) during a complete series of cycles in a minute multiplied by 2.	2 • (∑start(i) : start(n)(Tz • ΔØ))

Abbrevations: t, time(s); _start(i), start of the current push (sample); _end(i), end of the current push (sample); Ø, angle (rad); Fx, Fy and Fz, force components (N); Tz, torque around wheel axle (Nm).