iiwa Kinematics NodeRED Nodes

This custom Node-RED package is created by Orwa Diraneyya for inclusion in the demo app for the paper entitled 'TOWARDS A NOVEL, WEBASSEMBLY-BASED, ROBOTIC-SIMULATION WEB STACK' (to be published in the DETC2022 conference).

The package contains 3 nodes, which wrap the following IKFAST C++ functions:
- GetNumJoints
- ComputeFK
- ComputeIK

These nodes are listed under a category named 'robotics':

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
- JavaScript typed arrays
- Hello World in WebAssembly
- Passing and returning array parameters

Related Posts

- MDN WebAssembly documentation
- Code examples that accompany MDN WebAssembly documentation
- WebAssembly Example
- Standalone WebAssembly Example
- Cheerp Tutorial: Mixed mode C++ to WebAssembly and JavaScript
- Writing WebAssembly By Hand
- Emscripten
- Interacting with Code
- Emscripting a C library to Wasm

WASM Compilation

#### Option 1. Emscripten SDK

- Installation (Linux or OS X)

>$ git clone https://github.com/juj/emsdk.git

>$ cd emsdk

>$ ./emsdk install latest

>$ ./emsdk activate latest

>$ source ./emsdk_env.sh

- Compilation with emcc

> $ emcc main.c -s WASM=1 -o app.html

- Additional Toolkit WABT:WebAssembly Binary Toolkit

#### Option 2. WebAssembly for Node

> wa-compile -o main.wasm main.c

> wa-link` utility links multiple wasm files to one.

WASM Examples ( as a reference )

- https://github.com/Hanks10100/wasm-examples
- JPEG codec in WASM demo
- HumbleNet
- Getting Started With WebAssembly