Pt = Ph + Pm = max(0, Pp + Pa + k*v + f*wv²)
Pp = -m*g*vv
Pa = 1/2*m*(vdt² - v0²)/dt = m*a*(v0 + 1/2*a*dt)

Pt: total power, in W
Ph: mechanical human power, in W
Pm: mechanical motor power, in W ; this is not the electrical power, as the motor has an efficiency lower than 1
Pp: potential power (in W, due to potential energy change)
Pa: acceleration power (in W, due to kinetic energy change)
k: kinetic friction coefficient (dry friction)
f: fluid friction coefficient (air friction)
v: velocity, in m/s, assumed to be always positive or zero
vv: vertical velocity (in m/s, positive when going uphill)
wv: wind velocity, in m/s (velocity of the wind relatively to the vehicle, projected on the forward direction, can be approximated by wv = v)
g: gravity constant (-9.8 m.s⁻²)
m: mass in kg

vehicle constants:
- mass (m), including driver, passengers and other payloads ; easy to measure directly
- kinetic friction coefficient (k) ; difficult to measure, needs to be estimated from monitoring data
- fluid friction coefficient (f) ; difficult to measure, needs to be estimated from monitoring data