Convert the route into force

Estimate F = m·g·Crr for level rolling, m·g·sin(θ) for slope and m·a for acceleration. Add the components that occur together. Use measured rolling resistance when possible.

Check what torque cannot answer

Wheel torque divided by radius gives theoretical drive force. Actual force can be lower because the tire slips, current is limited, voltage sags or components overheat. The drive wheel also needs enough normal load.

Validation plan

Test worst-case payload, battery state, floor, ramp transition, start condition and repeated cycles. Record speed and temperature, not only whether the cart moved once.