Industrial Robot Mechanical Design

Toolchain for Toolpaths

CAD (FreeCAD) > export (stl, dxf, svg) > CAM (PyCAM) > export (gcode) > Machine Controller (EMC2) > export (logic signals) > Machine (CNC milling, various) > export (work)

In FreeCAD, a 3d mesh drawing can be exported as an stl file; alternatively, a 2d drawing can be exported as a dxf or svg file. Any of these files can then be imported in PyCAM, in which toolpaths can be generated for those drawings. These toolpaths can then be exported from PyCAM as a gcode file. EMC2 can then import the gcode file and simulate the toolpath, plus send logic signals to an external electronic controller that moves a machine to correspond to the toolpath. This toolchain allows digital fabrication to be utilized for the construction of the industrial robot.

Mechanical Concept

Motors

Brushed motors wear out relatively rapidly. Yet, the industrial robot must be designed for lifetime use. Therefore, AC brushless or DC brushless motors seem like the better design choice for electric drive.

For hydraulic drive, epicyclic (gerotor) motors seem to be the optimal choice for their low leakage, low speed, and high torque. Other types include vane motors and axial/radial piston motor

Gear Reduction

By virtue of using hydraulic drive, the rpms of the motors are low enough that we can get by with using a simple gearing system such as a gearbox that can be digitally fabricated.

Kinematic Parameters

The Denavit-Harten parameters are as follows, for joint(i): depth(i), normal length(i), z angle (i), x angle (i).

Joint(1): Depth(1)=0.2m , Normal Length(1)=0.2m , Z Angle(1)=90deg , X Angle(1)=*

Joint(2): Depth(2)=0.0m , Normal Length(2)=1.0m , Z Angle(2)=00deg , X Angle(2)=*

Joint(3): Depth(3)=0.0m , Normal Length(3)=0.1m , Z Angle(3)=90deg , X Angle(3)=*

Joint(4): Depth(4)=0.0m , Normal Length(4)=0.0m , Z Angle(4)=90deg , X Angle(4)=*

Joint(5): Depth(5)=0.2m , Normal Length(5)=0.0m , Z Angle(5)=90deg , X Angle(5)=*

where * is the joint variable