Node-red-contrib-rwth-bcma NPM

Inverse Kinematic Node

npm.io

This custom node is based on a low-level C++ implementation of an inverse-kinematic solver for an excavator.

The C++ solver was generated using IKFAST, a part of a robotic framework named OpenRAVE.

The method of using WebAssembly in a Node-RED node was inspired by the work of phyunsj with this this repository: https://github.com/phyunsj/node-red-native-addon

Compiling ik.c -> ik.wasm

Development

emcc --no-entry -o ik.wasm ik.cpp -Oz --profiling-funcs -s WASM=1 -s STANDALONE_WASM

Production

emcc --no-entry -o ik.wasm ik.cpp -Os -s WASM=1 -s STANDALONE_WASM

Hydraulic Simulation Node

WIP

Compiling hydraulic.wasm

..\..\emsdk\emsdk.bat activate 3.1.0

emcc --no-entry -fwrapv -DCLASSIC_INTERFACE=0 -DALLOCATIONFCN=1 -DMAT_FILE=0 -DONESTEPFCN=1 -DTERMFCN=1 -DMULTI_INSTANCE_CODE=1 -DINTEGER_CODE=0 -DMT=0  -DRT_MALLOC -DTID01EQ=1 -DMODEL=Open_Center_inport_outport -DNUMST=2 -DNCSTATES=6 -DHAVESTDIO -DRT -DUSE_RTMODEL --include-directory=. --include-directory=C:\PROGRA~1\MATLAB\R2021b\simulink\include --include-directory=C:\PROGRA~1\MATLAB\R2021b\simulink\src --include-directory=C:\PROGRA~1\MATLAB\R2021b\rtw\c\src --include-directory=C:\PROGRA~1\MATLAB\R2021b\rtw\c\src\ext_mode\common --include-directory=C:\PROGRA~1\MATLAB\R2021b\extern\include --include-directory=C:\PROGRA~1\MATLAB\R2021b\toolbox\aeroblks\aeroblks --include-directory=C:\PROGRA~1\MATLAB\R2021b\toolbox\aero\aero\src Open_Center_inport_outport.c Open_Center_inport_outport_data.c rtGetInf.c rtGetNaN.c rt_nonfinite.c rt_malloc_main.c -o hydraulic.wasm -Oz --profiling-funcs -s WASM=1 -s STANDALONE_WASM

Original documentation

This is the documentation from the original repository which I modified.

Passing String (or Array)

WebAssembly doesn't natively support a string type, it rather supports i32 / i64 / f32 / f64 value types as well as i8 / i16 for storage.

            var ptr = new Uint8Array(mem.buffer, 0, msg.payload.length );
             
            // String to UTF8
            var utf8 = unescape(encodeURIComponent(msg.payload));
            for (var i = 0; i < utf8.length; i++) {
                ptr[i] = utf8.charCodeAt(i);
            }
            
            instance.exports._lowercase(ptr); // Calling lowercase(char *ptr)
            
            // UTF8 to String
            msg.payload = utf8ToString(ptr);

You can interact with a WebAssembly instance using:

exports, where from JavaScript you call into WebAssembly, and WebAssembly returns a single value type.
imports where WebAssembly calls into JavaScript, with as many value types as you want (note: the count must be known at Module compilation time, this isn't an array and isn't variadic).
Memory.buffer, which is an ArrayBuffer that can be indexed using (among others) Uint8Array.

More about Array