Incidence Sideslip And Airspeed — Robotics/Flight Parameters

Robotics/Flight_Parameters/Incidence_Sideslip_And_Airspeed · 1 input / 3 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.

Incidence, Sideslip & Airspeed

Robotics / Flight Parameters

The three aerodynamic angles-and-speed of a body-axis velocity:

α = atan2(w, u), V = √(u² + v² + w²), β = asin(v / V)

α is the angle of attack, measured in the aircraft's plane of symmetry and ignoring v entirely; β is the sideslip, the angle the total velocity makes with that plane.

Ports

Vb – the velocity in body axes, a [3,1] column [u v w]’. Any consistent units.
α – the angle of attack in radians, a [1,1] scalar, four-quadrant, so a backwards flight path is not folded onto a forwards one.
β – the sideslip angle in radians, a [1,1] scalar, in [−π/2, π/2].
V – the airspeed, a [1,1] scalar, never negative.

Parameters

Sampling Time (s) – zero or less inherits the solver's rate; a positive value runs the block at that period.

There are no others: the velocity is all the block takes.

Code export

All ten targets: Python, MATLAB, Java, Rust, C, C++, VHDL, Verilog, SystemVerilog and PLC Structured Text.

The three HDL targets are simulation-only: a square root, a division and two inverse trigonometric calls, none of which exists in a Q16.16 datapath, so the values convert at the port boundary and evaluate in real. The cores simulate correctly and are not offered as synthesizable.

A zero velocity is the one input worth knowing about: α is atan2(0,0) = 0 in every target, and β would be 0/0 – the block answers 0 there rather than NaN, in all ten, because a vehicle that is not moving has no sideslip to report.

Simulink bridge

Import and export, mapped to Aerospace Blockset's aerolibasang/Incidence, Sideslip, & Airspeed. That block has no dialog parameters at all – measured in R2026a – so nothing is mapped and the add_block carrying nothing is itself the assertion. It defines no SampleTime either, so the rate stays on the ICore side.

⚠ The library block's own name carries an embedded newline, and the flattened spelling is Incidence, Sideslip, & Airspeed with no space after the comma – a path that differs by one space resolves to nothing, silently.

Notes

Algebraic and stateless: the outputs depend on this sample alone.
Not spherical polar. Cartesian To Spherical answers an elevation of atan2(z, √(x²+y²)); α here is atan2(w, u), which ignores v. The two agree only at zero sideslip.
The arcsine's argument is clamped to [−1, 1]. It cannot leave that interval mathematically, but one rounding step can when u and w are both zero, and asin of 1+ε is NaN rather than π/2.
Not linear, so the block carries no state space and model reduction correctly reports it as unmergeable.
Verified against R2026a: at [50 3 7]’ both this block and the Simulink one answer 0.13909594148207133, 0.059350718679965005 and 50.576674465607169.

Code facts#

Fact	Value
registered type	`Robotics/Flight_Parameters/Incidence_Sideslip_And_Airspeed`
family	`Robotics/Flight_Parameters`
solver environment class	`ICoreBlock_0_Robotics_1_Flight_Parameters_2_Incidence_Sideslip_And_Airspeed`
source	`src/ICoreBlocks/ICoreBlockLibrary/Blocks/Robotics/Flight_Parameters/Incidence_Sideslip_And_Airspeed/ICoreBlock_0_Robotics_1_Flight_Parameters_2_Incidence_Sideslip_And_Airspeed.cpp`
header	`src/ICoreBlocks/ICoreBlockLibrary/Blocks/Robotics/Flight_Parameters/Incidence_Sideslip_And_Airspeed/ICoreBlock_0_Robotics_1_Flight_Parameters_2_Incidence_Sideslip_And_Airspeed.h`
default size on canvas	124 × 84 px
ports at insert	1 in, 3 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`	Vb
2	out	`ICoreDouble`	alpha
3	out	`ICoreDouble`	beta
4	out	`ICoreDouble`	V

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#

No config variable beyond the Sampling Time (s) every block carries.

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	`aerolibasang/Incidence, Sideslip,\n& Airspeed`
port-count rule	`PortsParam::None`
`SampleTime` parameter	no — the counterpart defines none; the rate stays on the ICore side

Caveat (shown to the user): the Simulink block carries no dialog parameters and no SampleTime, so the whole mapping is the library path and the port list: one [3,1] velocity in, alpha, beta and V out in that order. The rate stays on the ICore side

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).

Incidence, Sideslip & Airspeed -- alpha, beta and |V| from a body-axis velocity alpha = atan2(w, u) the angle of attack V = sqrt(u^2+v^2+w^2) the airspeed beta = asin(v / V) the sideslip angle

MEASURED AGAINST R2026a rather than asserted: driven at [50 3 7]', Aerospace Blockset's aerolibasang/Incidence, Sideslip, & Airspeed answers 0.13909594148207133, 0.059350718679965005 and 50.576674465607169 -- atan2(7,50), asin(3/norm) and norm, to 1e-17. The block carries NO dialog parameters at all and no SampleTime.

⚠ THIS IS NOT SPHERICAL POLAR. Robotics/Coordinate_Transforms/Cartesian_To_Spherical answers an elevation of atan2(z, hypot(x, y)); alpha here is atan2(w, u), which ignores v entirely. The two agree only when the sideslip is zero, so one block cannot serve for the other.

⚠ THE ARCSINE'S ARGUMENT IS CLAMPED to [-1, 1]. It cannot leave that interval mathematically -- v is a component of the vector whose norm divides it -- but one rounding step can put it at 1+1eps when u and w are both zero, and asin() of that is NaN rather than pi/2. The clamp changes no answer a real velocity produces, and it makes the ten backends agree on the one input that could have separated them.

⚠ THE THREE HDL TARGETS ARE SIMULATION-ONLY: a root, a division and two inverse trigonometric calls, none of which exists in a Q16.16 datapath.

Sample results#

No stimulus produced a sampled output in this rig — Invalid input size at Incidence, Sideslip & Airspeed block: ICore Blocks/Home/Incidence Sideslip And Airspeed. 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 7a92e77df807c552be6236159919fcefe95c17d3 · produced by docsSample --out <folder> --blocks Dynamic_Pressure Mach_Number Incidence_And_Airspeed Incidence_Sideslip_And_Airspeed --steps 60

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