Parallel arms
An arm whose tool hangs from several thin links at once — the delta robot over a packing line, or the Stewart platform under a flight simulator.
- delta robot
- hexapod platform
- Stewart platform
- parallel robot
What it is
A parallel arm carries its end-effector on two or more kinematic chains working side by side, all joined to one moving platform. The motors stay on the fixed frame, so the moving parts are light rods and joints. That is the trade: very high speed and acceleration, good stiffness and precision, in exchange for a small, oddly shaped workspace and, on a delta, usually three or four axes. The ABB IRB 360 FlexPicker is the classic shape: three arms hanging from a ceiling mount, snatching items off a moving belt.
Names you will meet: delta robot, parallel robot, hexapod platform, Stewart platform. In this taxonomy it sits under Arm, and the test is that two or more chains carry the end-effector in parallel. A serial chain of joints, however many, is articulated.
What they are used for
- High-speed picking and packing — sorting food, pharmaceuticals and small goods from a conveyor into trays, usually with a vacuum gripper and a camera over the belt.
- Hygienic food handling — washdown and stainless delta pickers in wet, open-food lines where a serial arm is hard to clean.
- Motion platforms — Stewart platforms (hexapods) tilt and shake a cockpit, antenna or test rig with six stiff, precise axes.
- Precision positioning — small hexapods aligning optics and samples in labs.
What to compare
| Attribute | Why it matters | In this catalogue |
|---|---|---|
reach |
For a delta, the radius of the working circle under the frame (half the working diameter) | 565 mm (ABB Robotics IRB 360 FlexPicker) |
payload |
Light by design; the links are thin so they can move fast | 1 kg (ABB Robotics IRB 360 FlexPicker) |
axes |
Three for pure translation, four with a wrist twist, six on a hexapod platform | 4 (ABB Robotics IRB 360 FlexPicker) |
repeatability |
High, because the frame carries the motors and the moving mass is small | 0.1 mm (ABB Robotics IRB 360 FlexPicker) |
mounting |
Deltas hang from a ceiling or frame; hexapods sit on the floor or a bench | ceiling (1) |
ip_rating |
Washdown-rated versions for food and pharma | not yet in the catalogue |
In the catalogue
Professional / industrial: ABB Robotics IRB 360 FlexPicker
Edge cases
- Hexapod platforms (Stewart platforms): parallel arms, not legged robots. A six-legged walker is multi-legged.
- Delta-style 3D printers and CNC machines: machines, not robots; not catalogued.
- Cable-driven parallel robots: still parallel arms; the chains are cables.
- Parallel grippers: a component; nothing to do with parallel kinematics.
Related
Arm · Articulated arm · SCARA arm · Cartesian arm · Cylindrical & spherical arm · Vacuum gripper · Multi-legged
Rule of membership
End-effector carried by two or more kinematic chains acting in parallel.
Category rb-1-3 in the whatrobot taxonomy.