How Slow for Curves plans¶

Slow for Curves plans braking before a bend and restores speed as it opens, up to the next curve or your set speed.

1. It reads the road ahead. The camera planner uses the path the driving model predicts. The map planner uses curve speeds from your downloaded maps.
2. It gives each bend a speed at the grip limit below.
3. It works backward to the latest point where braking within the budget still reaches each bend at its speed.
4. It starts when it must: once the braking needed reaches 70% of the budget. The spare 30% covers hills and reading errors.
5. The lowest target wins among your set speed, both planners and Speed-Limit Assist.

Mazda runs the zoompilot planners described here. Every other brand runs sunnypilot's own Slow for Curves, unchanged.

the grip limit¶

Sideways pull stays at or under about 2.2 m/s² (about 0.22 g), depending on the curve's speed: 2.2 m/s² at 35 mph (56 km/h), 2.1 at 55 mph (89 km/h), 2.2 at 70 mph (113 km/h). It rises again at highway speed because banked highway curves hide some pull. The planner targets 95% of the limit to allow for lag.

how far it looks¶

The camera planner uses the whole predicted path. The model sees far bends as gentler than they are, so below 50 mph (80 km/h) zoompilot sharpens them (up to 1.5 times at 110 m). This fades out by 60 mph (97 km/h).

The first 3 s of path (4 s on the big driving model) is the near window. The model reads it well, so it decides whether you are in a curve. With your car's own cruise and a set speed under 50 mph, only the near window may ask for braking past the budget. That fades out by 60 mph.

in the curve and after¶

The planner stays on while the near window needs less than your speed plus 1 m/s (about 2 mph), or the braking needed stays above 30% of the budget. Then it lets go. Your car's cruise climbs back only as far as the next slow point ahead.

the commit hold below 50 mph¶

Below 50 mph the model can lose a bend it saw, then find it again closer. So with your car's own cruise, zoompilot remembers a bend that has called for slowing for 2 s until the near window reaches it. A slower bend replaces it. The hold also ends if the planner lets go or you pass 50 mph. It never runs with experimental speed control.

the map planner¶

A map target uses the same budget and 70% trigger, and never asks past the budget. Below 45 mph (72 km/h) it acts at once. Faster, it must first stay the slowest target ahead for up to 2.5 s (the full 2.5 s from 50 mph, 80 km/h), which filters out the map briefly placing you on a side street. If the map data drops out, the target lets go at once. At speed, a returning target waits the full time again.

how hard it may slow¶

With your car's own cruise, the cruise buttons lower the set speed toward the slowest point ahead, a few mph below your speed at a time. Presses and the cruise's reaction take time, so it starts braking earlier.

what you'll notice¶

• Back-to-back curves keep the speed down to the slowest one ahead.
• Lowest target: it never asks for less than 12 mph (20 km/h).
• Pressing the gas overrides it.

settings¶

Settings → Cruise → Slow for Curves: Vision and Settings → Cruise → Slow for Curves: Map. Both are off by default and work together. They turn on only when zoompilot can change your speed (experimental speed control or cruise-button control).