aim_map.h File Reference

Maps a target's image position to turret angles (pure C++20, natively tested). More...

#include <cstdint>
#include <optional>

Go to the source code of this file.

Classes
struct	aiming::Angles
	Turret pose: pan degrees from home (positive = right), tilt servo degrees (larger = up). More...
struct	aiming::CalPoint
	One calibration sample: the target's pixel and the turret angles that pointed at it. More...
struct	aiming::Pixel
	An image position in pixels; not clamped, so it can lie outside the frame. More...
struct	aiming::AimMap
	pan = pan_a * x + pan_b, tilt = tilt_a * y + tilt_b. More...
struct	aiming::ReachBox
	Rectangle of frame pixels (inclusive corners) with x0 <= x1 and y0 <= y1. More...

Functions
AimMap	aiming::default_map ()
	Camera next to the turret, 66 x 50 degree field of view, image centre = home.
std::optional< AimMap >	aiming::fit (const CalPoint &p1, const CalPoint &p2)
	Per-axis line through two calibration points; empty if they are too close or not finite.
ReachBox	aiming::reach_box (const AimMap &m)
	The image region whose aim lies inside the soft limits: the pixels where kPanMinDeg <= pan <= kPanMaxDeg and kTiltMinDeg <= tilt <= kTiltMaxDeg (the inverse of the limits through the map), ordered, clamped to the frame and rounded. An axis with a zero or non-finite slope spans the whole frame. A region wholly outside the frame collapses onto the nearest edge column or row.
uint8_t	aiming::limit_bits (Angles a)
	Soft-limit proximity bits for the HUD: 1 pan within kLimitMarginDeg of kPanMinDeg, 2 pan at the max, 4 tilt at the min, 8 tilt at the max (inclusive; beyond a limit counts too, a non-finite angle sets no bit).
Angles	aiming::clamp_angles (Angles a)
	Clamps angles to the soft limits; non-finite pan becomes 0 and non-finite tilt becomes kTiltHomeDeg first.
int32_t	aiming::pan_deg_to_steps (float deg)
	Converts pan degrees to 28BYJ-48 full steps (rounded). Non-finite input gives 0; the degrees are clamped to [kPanMinDeg, kPanMaxDeg] before rounding, so the result is always in [-512, 512].
float	aiming::pan_steps_to_deg (int32_t steps)
	Converts a pan step count (28BYJ-48 full steps from home) to degrees; the inverse of pan_deg_to_steps.

Variables
constexpr int32_t	aiming::kStepsPerRev = 2048
	28BYJ-48 full steps per revolution
constexpr float	aiming::kPanMinDeg = -90.0f
constexpr float	aiming::kPanMaxDeg = 90.0f
constexpr float	aiming::kTiltMinDeg = 20.0f
constexpr float	aiming::kTiltMaxDeg = 160.0f
constexpr float	aiming::kTiltHomeDeg = 90.0f
constexpr int	aiming::kFrameW = 320
	QVGA.
constexpr int	aiming::kFrameH = 240
constexpr float	aiming::kLimitMarginDeg = 0.5f
	limit_bits() reports an axis this close to a soft limit
constexpr float	aiming::kMinCalDx = 80.0f
	closer calibration points amplify aiming error
constexpr float	aiming::kMinCalDy = 60.0f

Detailed Description

Maps a target's image position to turret angles (pure C++20, natively tested).

The camera is fixed (not on the turret), so aiming is open-loop: pan depends linearly on image x and tilt on image y. The map comes from a 2-point joystick calibration, or from default_map() (camera next to the turret, OV3660 field of view) until one exists. Angles: pan degrees from home (positive = right), tilt servo degrees (larger = up).