Horizontal Wind Model — Robotics/Wind

Robotics/Wind/Horizontal_Wind_Model · 1 input / 1 output port(s) at insert · exports to Python, MATLAB, Java, Rust, C, C++, VHDL, Verilog, SystemVerilog, PLC Structured Text

Description#

The block's own DESCRIPTION_HTML, rendered verbatim — the same text the config dialog's info panel and the library navigator show. Fix a wrong sentence in the block's .cpp (R-D9), never here.

Horizontal Wind Model

Robotics / Wind

A steady horizontal wind of a given speed, blowing from a given direction, handed back in body axes. It is the constant-wind block of the Aerospace Blockset – not a climatology: the speed and direction are the block's own parameters, and nothing depends on altitude, date or position.

ψ = W_deg·(π/180) – the direction the wind blows FROM, in radians clockwise from north.
v = V·[−cos ψ; −sin ψ; 0] – the wind in the inertial north-east-down frame.
w = DCM·v – the same wind rotated into body axes.

Ports

DCM – the direction cosine matrix from inertial (north-east-down) to body axes, [3,3].
Output – w, the wind in body axes, [3,1], in the unit the wind speed parameter is given in.

Parameters

Units – which unit the wind speed (and therefore the output) is in: Metric (MKS) for m/s (the default), English (Velocity in ft/s) or English (Velocity in kts). It changes no arithmetic: the block converts only the angle.
Wind Speed At Altitude – V, a scalar. Defaults to 15.
Wind Direction At Altitude (deg) – W_deg, a scalar, the direction the wind blows FROM, in degrees clockwise from north. Defaults to 0.
Sampling Time (s) – zero or less inherits the solver's rate; a positive value runs the block at that period.

Code export

All ten targets: Python, MATLAB, Java, Rust, C, C++, VHDL, Verilog, SystemVerilog and PLC Structured Text. The inertial wind v is folded to two constants at export time, so every core computes two products and one sum per output element.

The three HDL targets are genuine Q16.16: a constant times a DCM element needs no real arithmetic, so the cores are synthesizable. The two constants are quantized to Q16.16 (one step is about 1.5×10⁻⁵), and so is the answer.

Simulink bridge

Import and export, mapped to Aerospace Blockset's aerolibwind2/Horizontal Wind Model: Units → units 1:1 and therefore lossless, Wind Speed At Altitude → Vwind and Wind Direction At Altitude (deg) → Wdeg. The two source popups, Vw_source and W_source, are pinned to Internal: setting either to External adds a port to the Simulink block, and this block's ports do not follow a parameter, so importing a Simulink block set to External reports the difference rather than accepting it. "Sampling Time (s)" does not cross: the Simulink block defines no SampleTime parameter, measured on R2026a.

Notes

Stateless and algebraic: the output depends only on this sample's DCM.
The sign is the aeronautical one. ψ is where the wind comes FROM, so a 15 m/s northerly (ψ = 0) is −15 m/s along north.
Bit-exact with Simulink, measured: the angle is converted as W_deg·(π/180), which is not the same double as W_deg·π/180.
The DCM is used as given; nothing checks that it is orthonormal.

Code facts#

Fact	Value
registered type	`Robotics/Wind/Horizontal_Wind_Model`
family	`Robotics/Wind`
solver environment class	`ICoreBlock_0_Robotics_1_Wind_2_Horizontal_Wind_Model`
source	`src/ICoreBlocks/ICoreBlockLibrary/Blocks/Robotics/Wind/Horizontal_Wind_Model/ICoreBlock_0_Robotics_1_Wind_2_Horizontal_Wind_Model.cpp`
header	`src/ICoreBlocks/ICoreBlockLibrary/Blocks/Robotics/Wind/Horizontal_Wind_Model/ICoreBlock_0_Robotics_1_Wind_2_Horizontal_Wind_Model.h`
default size on canvas	120 × 60 px
ports at insert	1 in, 1 out
code generators implemented	`Python`, `MATLAB`, `Java`, `Rust`, `C`, `C++`, `VHDL`, `Verilog`, `SystemVerilog`, `PLC Structured Text`

Ports#

#	Direction	Signal type	Description label
1	in	`ICoreDouble`	DCM
2	out	`ICoreDouble`	—

Ports the constructor creates. A block whose port list changes with its configuration adds or removes ports at load time; the count above is the one a freshly inserted block has.

Configuration variables#

Config variable	Default	Simulink parameter
`Units`	`Metric (MKS)%~%English (Velocity in ft/s)%~%English (Velo…`	`units`
`Wind Speed At Altitude`	`15`	`Vwind`
`Wind Direction At Altitude (deg)`	`0`	`Wdeg`

Every block also carries Sampling Time (s) from ICoreBlockSolverEnvironment: zero or less inherits the solver's rate, a positive value runs the block at that period.

Simulink bridge#


support	`Support::Both`
Simulink path	`aerolibwind2/Horizontal Wind Model`
port-count rule	`PortsParam::None`
`SampleTime` parameter	no — the counterpart defines none; the rate stays on the ICore side
always set	`Vw_source` = `Internal`, `W_source` = `Internal`

ICore config	Simulink parameter	Value translation
`Units`	`units`	`Metric (MKS)` → `Metric (MKS)`, `English (Velocity in ft/s)` → `English (Velocity in ft/s)`, `English (Velocity in kts)` → `English (Velocity in kts)`
`Wind Speed At Altitude`	`Vwind`	passes through
`Wind Direction At Altitude (deg)`	`Wdeg`	passes through

Caveat (shown to the user): aerolibwind2/Horizontal Wind Model has NO SampleTime parameter (verified against the R2026a block dialog), so "Sampling Time (s)" does not cross. Vw_source and W_source are pinned to Internal because External moves that block's port list

Catalog contract: src/ICoreBlocks/ICoreCoder/ICoreCommandSystem/SimulinkBridge/ICoreSimulinkBlockCatalog.h

Description vs code#

The checker has a blind spot here — it could not resolve something (a grouped port bullet, a computed config name), which is reported and never counted as a pass. A reader has to settle it:

B0 every stimulus in the sample errored — cross-checks skipped

The verdict above is tools/docs/check_block_descriptions.py (P7.1), which compares LISTS. It cannot read a sentence: "stateless" on a block with a state, an initial-value semantic the recursion does not implement, a "not synthesizable" caveat the HDL banner contradicts. That is the agent audit (P7.3) on BLOCK_DESCRIPTION_AUDIT.md, and this tool's green is not a substitute for one.

The top comment of the block's .cpp — the maths, the realization and the export strategy, addressed to whoever changes it. It must not contradict the description above (P7.5).

Horizontal Wind Model — a steady wind from a fixed direction, rotated into body axes psi = Wdeg * (pi/180) v = V * [-cos psi; -sin psi; 0] (the inertial, north-east-down wind) w = DCM * v

⚠ MEASURED AGAINST R2026a before any of it was written: aerolibwind2/Horizontal Wind Model is a SinCos on the direction (through a deg -> rad Unit Conversion), a Mux [cos; sin; 0], a Gain of -1, an element-wise Product with the speed and a matrix Product with the DCM. The chain above reproduces it BIT-FOR-BIT (max |error| 0, not one element different) over 400 random (DCM, V, psi) samples with psi in [-720, 720] deg, in all three unit systems. Two spellings of the conversion that look equivalent are NOT: Wdeg*pi/180 and Wdeg/180*pi each miss by an ULP on over half the samples. And the unit system changes nothing: it names V's unit, the output is in the same one, and the block converts only the ANGLE.

The dialog's two "source" popups (Vw_source, W_source) are pinned to Internal: External moves the Simulink block's port list, and an ICore block's ports do not follow a config.

v is a constant, folded at export time, so every core is two products and one sum per row -- which keeps the three HDL targets GENUINE Q16.16.

Sample results#

No stimulus produced a sampled output in this rig — Invalid input size at Horizontal Wind Model block: ICore Blocks/Home/Horizontal Wind Model. That is a fact about the single-block rig, not a verdict on the block: an offline batch fit, a block whose output only appears at onSolverFinish, or one that needs a driven environment cannot be exercised alone.

Category unsampled · sample time 0.1 · 60 steps · commit c90ce53c01 · produced by docsSample --out <folder> --blocks Horizontal_Wind_Model --steps 60

Sample data: docs/generated/samples/Robotics__Wind__Horizontal_Wind_Model.json

Horizontal Wind Model — Robotics/Wind

Description#