Constant and gradual motion is easier to predict than sudden acceleration
Aliases: motion smoothness · velocity continuity · jerk minimisation
What it is
Smooth motion predictability is the ease of extrapolating near-future robot occupancy when velocity is constant or changes continuously. The requirement is not perpetual constant speed but observable regularity in velocity, acceleration, and jerk.
Why it happens
People extrapolate recent velocity and heading. Continuous change introduces prediction error gradually and allows correction; abrupt acceleration produces a large error at once and removes avoidance time. High jerk also couples postural, acoustic, and vibration transients that suggest instability. Smooth profiles reduce impact and make dynamics learnable.
Studying it
Velocity profiles can be compared at matched endpoints, peak speed, and duration using future-position prediction, avoidance onset, closest approach, surprise, and comfort. Slow-versus-fast comparisons do not isolate smoothness. Actual motion logs, payload, and floor conditions matter because commanded profiles may not be realised.
Where it stops holding
Smooth is not synonymous with safe: steady high speed may still be unstoppable, and abrupt evasion can prevent collision. Regular motion can also induce overconfidence that the path will not change. Under frequent replanning, safety can require responsiveness over smoothness.
Applying it
- Limit velocity, acceleration, and jerk near people, calibrated by payload.
- Join replanned segments continuously where possible; otherwise slow and preview the discontinuity.
- Have observers continuously forecast occupancy from measured trajectories and evaluate prediction error, closest approach, and emergency exceptions.
Related
- Same group: X2.05.2 Direction or speed discontinuities are perceived as loss of control or failure · X2.05.3 Unavoidable discontinuities require a perceptible warning · X2.05.4 Predictability directly trades off against task efficiency
- Adjacent: X2.02 Motion legibility · X5.01 Physical safety boundaries
- Search terms:
motion smoothness·jerk minimization·trajectory prediction