saxis - a 6 degrees of freedom robot arm

Overview

This program models a 6 degrees of rotational freedom robot arm using the sixaxis kinematics package. The arm renders via a web page using the three.js rendering API.

To run the program you should do:

$ git clone https://github.com/tinkerator/saxis
$ cd saxis
$ git submodule init
$ git submodule update
$ go mod tidy
$ go build
$ ./saxis

NOTE The git submodule ... parts are to cache a local copy of the three.js sources that are needed to get the 3D rendering of the robot to work.

Then you point your web browser at http://localhost:8080 and watch the saxis robot dance a Hilbert curve with the various modes of movement that it supports.

What you see looks like this:

The saxis program cycles through a series of programmed sequences: program numbers 1, 2, … There are 4 distinct sequences that endlessly repeat. They deomonstrate the zappem.net/pub/kinematics/sixaxis robot motion patterns as follows:

• 1,5,9,… Joined mode determines the pose for the robot at the next node of the Hilbert curve and smoothly interpolates all of the joint angles from the last pose to that pose. It sort of follows the curve.

• 2,6,10,… Arc mode subtends an arc of --arc degrees (defaults to 120) between the nodes of the Hilbert curve. The robot only intersects the curve at these nodes and otherwise bounces away from the line.

• 3,7,11,… Linear mode rigidly follows the actual linear segments of the Hilbert curve. This motion is the most robotic.

• 4,8,12,… Near mode is the most fluid motion. It cuts the corners (nodes) of the Hilbert curve leaving the official line at about 1/7th of the line from each node. It is this program that is recorded (“OFF AIR” -> “ON AIR”) for later saving via the “SAVE VIDEO” button. If you click this labeled button, a sample.webm video file is saved where your browser saves files (and not the working directory of the saxis program).

Notes for submodules

This was the setup for the threejs code:

$ git submodule add https://github.com/mrdoob/three.js.git

The various …min.js files from this submodule are symbolically linked from ./html/js/ locations.

License info

The saxis program is distributed with the same BSD 3-clause license as that used by golang itself. Viewing in a browser depends on three.js to render its image in a browser and that has its own MIT license.

Reporting bugs and feature requests

The saxis program was developed purely out of self-interest to try to understand how robots like this work. Should you find a bug or want to suggest a feature addition, please use the bug tracker.