Polyline

A polyline, in wafer-handling automation, is the defined motion path a transfer robot follows through the chamber — a sequence of straight-line segments and waypoints connecting pick, approach, and place positions — that the robot's motion controller executes exactly the same way every single cycle, rather than improvising a path in real time.

Robot needs to move a wafer from point A to point B without collision
The path between them has to clear chamber hardware every single time
Polyline definition and execution
Waypoints defined during setup
Pick position, approach point(s), place position — each a precise coordinate
Straight-line segments connect them
Motion controller interpolates each segment at commanded speed/acceleration
Same polyline executed every cycle
No real-time path planning — the route is fixed in advance
Wafer arrives at the place position, same route every time
Repeatability, not real-time obstacle avoidance, is the design goal

Defining the path as a fixed polyline, rather than having the robot plan a route in real time, is a deliberate tradeoff that favors repeatability over flexibility. A wafer-handling robot's environment — the chamber, the load lock, the pedestal — is static and precisely known in advance, so there's no need for the kind of real-time obstacle-sensing path planning a robot operating in an unpredictable environment would require; defining the exact waypoints and connecting segments once, during tool setup and qualification, and then executing that identical polyline every cycle afterward gives engineers a verifiable, repeatable path that's been checked for clearance against every piece of chamber hardware in advance, rather than trusting a real-time planner to avoid a collision correctly on every single pick.

Polyline — a Fixed, Verified Path Through the Chamber waypoints and segments defined once, executed identically every cycle Chamber top-down view with robot polyline Load lock Pedestal chamber hardware to clear polyline: pick → approach waypoint → approach waypoint → place identical segments and waypoints run every single cycle, never re-planned in real time

Approach waypoints exist specifically to control the robot's orientation and velocity right before the critical pick or place moment, which a single straight-line move from start to finish wouldn't manage well. A robot can't simply travel in one straight line from its resting position directly to a precise pick point and expect the end-effector to arrive correctly oriented and at a safe approach speed — intermediate waypoints break the move into segments that let the controller decelerate, reorient, and align the end-effector cleanly just before contact, which is exactly why a realistic polyline usually has several waypoints clustered near each pick or place position rather than one long segment covering the whole move.

A polyline is the quiet, unglamorous piece of motion-planning infrastructure that makes every FI-robot and mainframe-robot pick-and-place cycle covered elsewhere in this project actually repeatable — defined once during setup, verified against every piece of chamber hardware, and then trusted to run exactly the same way thousands of times without any real-time decision-making at all.

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