Robotic hanging tray reduces spillage with pendular motion
Researchers solve the waiter's problem with a simple rope-suspended tray.
In a new paper, Heins and Schoellig tackle the classic 'waiter's problem'—moving objects on a tray without spilling. Prior solutions used rigidly grasped trays, requiring complex 6-DOF arms to simulate pendular motion that minimizes shear forces. The team's innovation is a simple hanging tray: a tray suspended from the robot's end effector by ropes, behaving like a three-dimensional pendulum.
This design inherently provides pendular motion, reducing both sliding of rigid objects and sloshing in liquid containers. Crucially, it only needs a 3-DOF mobile base, lowering cost and complexity. Experiments on real hardware confirmed substantial improvements. The system was also integrated with computer vision to detect raised hands and steer toward patrons, creating an interactive robot waiter demonstration.
- Uses a tray suspended by ropes from robot's end effector to create natural pendulum motion
- Requires only a 3-DOF mobile base instead of a full 6-DOF manipulator arm
- Significantly reduces sliding of objects and sloshing of liquids compared to rigidly-held trays
Why It Matters
Simpler, cheaper robot waiters that reliably transport drinks and plates without spilling.