Anatomy of a cobot (3D)

← Robot list · Cobot page

Turn the robot with the mouse or your finger. Click an axis (a coloured circle or a card) to light up its ring and its axis and to read its description, press X-ray to look inside at the motors, gearboxes, controller and cables, and move each joint with its slider.

Turns the whole robot around its vertical axis.

Lifts the upper arm. The joint is offset sideways from the arm.

Folds the forearm.

First wrist joint, parallel to the shoulder and the elbow.

Second wrist joint, perpendicular to wrist 1. With the offsets, its axis does not cross the others: the wrist is not spherical.

Spins the tool flange. When J5 = 0, wrist 1 and wrist 3 line up: a wrist singularity.

What is inside each joint?

Compact joint modules: each joint is a tube with a brushless motor, a harmonic-drive gearbox and the electronics inside.
Two encoders per joint (motor side and output side) and a torque sensor or current sensing: the controller feels contact forces and stops when it touches a person.
Brake in every joint, and a safety-rated stop circuit.
Cables run inside the tubes, with the controller in a separate box connected by one cable.
Rounded shapes, light weight, limited force: made to work next to people (see “How a cobot stays safe”).

The angles of this 3D model are those of the drawing, with a zero chosen for display: they differ by a constant from the DH angles of the robot page. The model is simplified: the real inside depends on the make.