Detailed Description

Definition at line 90 of file thermal_friction.hpp.

#include <thermal_friction.hpp>

Public Member Functions
void	set_limits (const float *limits, uint8_t slices)
	The cold static limit per force slice — the friction-curve bow's `limits`

void	set_force_su (float su)
	Bow force across the slices [0, 1]; the cold limit interpolates between them.

void	set_rosin (float heat, float tau_ms, float convect, float mu_ratio, float cold_gain=DEFAULT_COLD_GAIN)
	The rosin: how it heats, cools and softens (configuration, not signals)

void	set_fast_cooling (float fast_ms, float fast_share)
	The fast cooling component: its time constant and the share of the heat it takes.

float	mu_rel () const
	Friction relative to cold, from the temperature: 1 cold down to mu_ratio hot.

void	advance (float force, float v_slip)
	Advance the contact one sample from a force and sliding speed found elsewhere.

float	process (float dv_free)
	One sample: relative velocity in, injection force out.

bool	sticking () const
	True while the string travels with the bow.

float	limit () const
	The static limit right now, warmed: where the string would release.

float	temperature () const
	Contact temperature as a fraction of the range over which the rosin softens.

void	reset ()
	Cold and stuck.

diagram::Ports	describe (diagram::Graph &g, uint8_t group, const char *name="bow (thermal)") const
	One Junction node: the friction nonlinearity. Never called from audio code (AP-037).

Static Public Attributes
static constexpr float	DEFAULT_MU_RATIO = 0.35f / 1.2f
	Rosin, as Woodhouse measured it: friction at full heat is this fraction of cold.

static constexpr float	DEFAULT_HEAT = 2000.0f

static constexpr float	DEFAULT_TAU_MS = 10.0f
	Conduction into the string and the bow: the slow component's time to cool by 1/e.

static constexpr float	DEFAULT_CONVECT = 0.0f
	Convection: cold rosin flowing into the contact, per unit sliding speed per second.

static constexpr float	DEFAULT_COLD_GAIN = 1.0f

static constexpr float	DEFAULT_FAST_MS = 0.5f
	The fast cooling component: time constant and the share of heat it takes.

static constexpr float	DEFAULT_FAST_SHARE = 0.6f

Member Function Documentation

◆ set_limits()

void sbl::dsp::pm::ThermalFriction::set_limits	(	const float *	limits,
		uint8_t	slices
	)

inline

The cold static limit per force slice — the friction-curve bow's limits

Parameters

limits	one static-friction limit per slice, light bow first
slices	number of slices

Definition at line 118 of file thermal_friction.hpp.

References set_force_su().

Referenced by sbl::dsp::pm::HybridFriction::set_bow().

◆ set_force_su()

void sbl::dsp::pm::ThermalFriction::set_force_su ( float su )

inline

Bow force across the slices [0, 1]; the cold limit interpolates between them.

Definition at line 125 of file thermal_friction.hpp.

Referenced by sbl::dsp::pm::HybridFriction::set_force_su(), set_limits(), and set_rosin().

◆ set_rosin()

void sbl::dsp::pm::ThermalFriction::set_rosin	(	float	heat,
		float	tau_ms,
		float	convect,
		float	mu_ratio,
		float	cold_gain = `DEFAULT_COLD_GAIN`
	)

inline

The rosin: how it heats, cools and softens (configuration, not signals)

Parameters

heat	temperature fraction per unit of force·speed per second
tau_ms	conduction time constant
convect	convection coefficient per unit sliding speed per second
mu_ratio	friction at full heat relative to cold, in (0, 1]
cold_gain	the cold limit as a multiple of the table's limit

Definition at line 147 of file thermal_friction.hpp.

References DEFAULT_COLD_GAIN, DEFAULT_MU_RATIO, and set_force_su().

◆ set_fast_cooling()

void sbl::dsp::pm::ThermalFriction::set_fast_cooling	(	float	fast_ms,
		float	fast_share
	)

inline

The fast cooling component: its time constant and the share of the heat it takes.

Definition at line 158 of file thermal_friction.hpp.

◆ mu_rel()

float sbl::dsp::pm::ThermalFriction::mu_rel ( ) const

inline

Friction relative to cold, from the temperature: 1 cold down to mu_ratio hot.

Definition at line 164 of file thermal_friction.hpp.

References temperature().

Referenced by limit(), process(), and sbl::dsp::pm::HybridFriction::set_force_su().

◆ advance()

void sbl::dsp::pm::ThermalFriction::advance	(	float	force,
		float	v_slip
	)

inline

Advance the contact one sample from a force and sliding speed found elsewhere.

For the hybrid bow: the friction curve finds the force; this keeps the temperature. Sliding speed 0 while stuck.

Definition at line 172 of file thermal_friction.hpp.

References sbl::dsp::math::clamp01().

Referenced by sbl::dsp::pm::HybridFriction::process(), and process().

◆ process()

float sbl::dsp::pm::ThermalFriction::process ( float dv_free )

inline

One sample: relative velocity in, injection force out.

Parameters

dv_free v_bow - v_incoming, in wave variables

Definition at line 187 of file thermal_friction.hpp.

References advance(), limit(), and mu_rel().

◆ sticking()

bool sbl::dsp::pm::ThermalFriction::sticking ( ) const

inline

True while the string travels with the bow.

Definition at line 212 of file thermal_friction.hpp.

◆ limit()

float sbl::dsp::pm::ThermalFriction::limit ( ) const

inline

The static limit right now, warmed: where the string would release.

Definition at line 215 of file thermal_friction.hpp.

References mu_rel().

Referenced by process().

◆ temperature()

float sbl::dsp::pm::ThermalFriction::temperature ( ) const

inline

Contact temperature as a fraction of the range over which the rosin softens.

Definition at line 218 of file thermal_friction.hpp.

Referenced by mu_rel(), and sbl::dsp::pm::HybridFriction::temperature().

◆ reset()

void sbl::dsp::pm::ThermalFriction::reset ( )

inline

Cold and stuck.

Definition at line 224 of file thermal_friction.hpp.

References sbl::dsp::types::SAMPLE_RATE_F.

Referenced by sbl::dsp::pm::HybridFriction::reset().

◆ describe()

diagram::Ports sbl::dsp::pm::ThermalFriction::describe	(	diagram::Graph &	g,
		uint8_t	group,
		const char *	name = `"bow (thermal)"`
	)		const

inline

One Junction node: the friction nonlinearity. Never called from audio code (AP-037).

Definition at line 232 of file thermal_friction.hpp.

References sbl::dsp::diagram::Graph::add_node(), sbl::dsp::diagram::Ports::group, sbl::dsp::diagram::Ports::in, sbl::dsp::diagram::Junction, and sbl::dsp::diagram::Ports::out.

Member Data Documentation

◆ DEFAULT_MU_RATIO

constexpr float sbl::dsp::pm::ThermalFriction::DEFAULT_MU_RATIO = 0.35f / 1.2f

staticconstexpr

Rosin, as Woodhouse measured it: friction at full heat is this fraction of cold.

Note: All public methods are ISR-safe — bounded computation, no I/O.

Definition at line 95 of file thermal_friction.hpp.

Referenced by set_rosin().

◆ DEFAULT_HEAT

constexpr float sbl::dsp::pm::ThermalFriction::DEFAULT_HEAT = 2000.0f

staticconstexpr

Fraction of the range per unit of (force · sliding speed) per second. Calibrated 2026-09-15 on the Davis Jr. string: Helmholtz at C3 with the body, C3–C5 bare (AP-040 Phase 4 addenda).

Definition at line 99 of file thermal_friction.hpp.

◆ DEFAULT_TAU_MS

constexpr float sbl::dsp::pm::ThermalFriction::DEFAULT_TAU_MS = 10.0f

staticconstexpr

Conduction into the string and the bow: the slow component's time to cool by 1/e.

Definition at line 101 of file thermal_friction.hpp.

◆ DEFAULT_CONVECT

constexpr float sbl::dsp::pm::ThermalFriction::DEFAULT_CONVECT = 0.0f

staticconstexpr

Convection: cold rosin flowing into the contact, per unit sliding speed per second.

Definition at line 103 of file thermal_friction.hpp.

◆ DEFAULT_COLD_GAIN

constexpr float sbl::dsp::pm::ThermalFriction::DEFAULT_COLD_GAIN = 1.0f

staticconstexpr

The cold limit over the table's. 1: cold equals the table's limit. (Any more and this waveguide's stuck force, capped by loop loss at a few bow speeds, never reaches it.)

Definition at line 107 of file thermal_friction.hpp.

Referenced by set_rosin().

◆ DEFAULT_FAST_MS

constexpr float sbl::dsp::pm::ThermalFriction::DEFAULT_FAST_MS = 0.5f

staticconstexpr

The fast cooling component: time constant and the share of heat it takes.

Definition at line 109 of file thermal_friction.hpp.

◆ DEFAULT_FAST_SHARE

constexpr float sbl::dsp::pm::ThermalFriction::DEFAULT_FAST_SHARE = 0.6f

staticconstexpr

Definition at line 110 of file thermal_friction.hpp.

The documentation for this class was generated from the following file:

src/sbl/dsp/pm/thermal_friction.hpp

Detailed Description

Public Member Functions

Static Public Attributes

Member Function Documentation

◆ set_limits()

◆ set_force_su()

◆ set_rosin()

◆ set_fast_cooling()

◆ mu_rel()

◆ advance()

◆ process()

◆ sticking()

◆ limit()

◆ temperature()

◆ reset()

◆ describe()

Member Data Documentation

◆ DEFAULT_MU_RATIO

◆ DEFAULT_HEAT

◆ DEFAULT_TAU_MS

◆ DEFAULT_CONVECT

◆ DEFAULT_COLD_GAIN

◆ DEFAULT_FAST_MS

◆ DEFAULT_FAST_SHARE