A Cartesian robot is a robot system that moves along mutually perpendicular linear axes: X, Y and Z. When the axes are carried like a bridge on two supports it is also called a gantry robot. It is simple in structure, covers a large work area and is very precise. In this article we explain the parts of a Cartesian robot, its pros and cons compared with a robot arm and the jobs it is chosen for.
Parts of a Cartesian robot
- Linear axis modules: The rail and body on which the carriage slides; each axis is one module.
- Drive: Ball screw (precise, short to medium travel), toothed belt (fast, long travel) or rack and pinion (very long and heavy axes).
- Servo motors and drives: Control position and speed of each axis.
- End effector: Gripper, vacuum, welding torch or dispensing head. A rotary axis can be added at the end if needed.
- Control: A PLC or motion controller and an operator screen.
Cartesian robot or robot arm?
| Cartesian robot | 6-axis robot arm | |
|---|---|---|
| Work area | Rectangular; can be extended to many metres by lengthening the axes. | Spherical; limited by reach. |
| Approach angles | Limited; usually works from above. | Can approach from any angle. |
| Rigidity and precision | High; little deflection even under heavy loads. | Good; payload drops as reach increases. |
| Programming | Simple; coordinates map directly to axis positions. | Needs inverse kinematics; more complex. |
| Cost | Usually lower for simple tasks. | More economical for versatile tasks. |
For robot arm axes see what is a 6-axis robot arm?
Where are Cartesian robots used?
- CNC and press tending: Loading and unloading parts.
- Palletising and stacking: Heavy products over large areas.
- Cartesian welding robots: Carrying the torch at constant speed along long straight seams on tanks and beams.
- Dispensing and gluing: Silicone, adhesive and gasket application.
- Cutting and marking: Plasma, laser and waterjet tables are Cartesian systems too.
Designing a Cartesian robot
- Axis length and deflection: On long axes, beam sag under its own weight and the load must be calculated.
- Drive choice: Screw, belt or rack depending on speed, precision and travel.
- Dynamic loads: Forces from fast acceleration can make the structure vibrate.
- Cable chain: Tidy routing of cables and hoses to moving axes.
- Safety: Guarding the work area with fencing or light curtains.
Cartesian systems with DKT
Cartesian systems lend themselves to job-specific design more than robot arms do. We design the system in SolidWorks, carry out strength and deflection calculations, show the motion with animation and write the control software. If needed we add our camera and laser-based vision system.
Summary
- A Cartesian robot moves on linear X, Y and Z axes; the bridge type is called a gantry.
- Large work area, high rigidity and simple programming are its strengths.
- If the part must be approached from different angles, a robot arm is the better fit.
- Deflection, drive choice and dynamic loads dominate the design.
Cartesian system or robot arm?
Tell us about your job; we will work out together which is more suitable and economical.
For our robot projects see the industrial robot arm page.