Digital Twin Series · Level 2 · Machine simulation
Robot and CNC Digital Twins
Can we program, check and speed up a robot cell or a CNC machine on the computer, before we run the real one?
A robot twin and a CNC twin are virtual copies of the machine, its tooling and its controller. You run the robot program or the G-code on the copy first, so collisions, limit violations and slow motions show up on the screen instead of on the machine. This page puts both side by side and gives you six working tools: a robot program checker, a robot cycle time optimiser, a CNC feed and cycle time calculator, a machine limits and collision check, a tool deflection check for part accuracy, and a live status monitor.
| Program line | What the twin checks | Result |
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Tick the mistakes you want to put into the program, and the twin reports which lines it would catch. A real validation also runs the controller itself (a virtual controller) so I/O and logic behave as on the robot.
A simple motion model: each straight move is a trapezoid of acceleration, constant speed and deceleration. A fine point makes the robot stop at every corner. A blend radius lets it pass the corner without stopping, slower for a small radius. Real robots also limit joint speeds, so treat the result as a first estimate to confirm in the robot simulation software.
Spindle speed n = 1000 × cutting speed / (π × diameter). Feed rate = n × feed per tooth × number of flutes. Cutting time = path length / feed rate. Spindle power uses the specific cutting force of the material, which is a typical handbook value and varies with tool and conditions. Tool path simulation gives the real time from the machine's own motion limits.
A twin checks the tool, holder, spindle, fixture and machine against each other at every point of the program. Here you can see one case: a tool holder against the vice jaw. The twin uses the real 3D shapes, not simple circles, so use this to understand the idea, not to approve a program.
Indicative estimate: the cutter is treated as a cantilever beam, with a reduced effective diameter for the flutes, a modulus of 600 GPa for carbide and an average cutting force from the specific cutting force. It shows the trend (overhang matters most) and not an exact error. Compare simulated against measured parts to calibrate it, as in the fidelity page of this series.
Simulated values, to show the idea. A connected twin compares live data with what the model predicts and raises an alert when they differ. Real data comes from the robot controller or the CNC controller (for example over OPC UA or MTConnect), as explained in the communication and data flow pages of this series.
| Area | Examples | Used for |
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Examples only, not a recommendation or a complete list. Most robot tools simulate motion and paths; only some include a virtual copy of the robot's own controller, so check that when you choose.
Figures are indicative and the models are simplified. Always confirm programs and settings on your own equipment with the manufacturer's tools.