#conveyorplc

Conveyor with robot integration is a material handling setup where a robot arm works directly alongside a conveyor line, coordinating its motion with the moving or indexing track instead of operating as a separate machine. The conveyor feeds workpieces or workpiece carriers to the robot's work envelope, while the robot controller reads position data from an encoder, vision system, or PLC signal to know exactly where each part sits. This lets the robot pick, place, assemble, or inspect parts in sync with the line's speed and station timing. Safety methods like speed and separation monitoring or power and force limiting govern how closely a person can work nearby.



Why Robot Collaboration Starts With the Conveyor Design

A circular conveyor line works with a robot under one condition. In general, the track and the arm must share the same reference frame. The robot needs to know where a workpiece carrier sits at every instant, not just where it started. As a result, conveyor robot integration begins at the mechanical layer. The mechanical layout gets fixed first, and the program comes second. In addition, track geometry, carrier spacing, and station layout set clear limits on where the robot can reach. Timing limits follow the same layout too. In practice, a circular conveyor system with fixed indexing stations gives a robot an easier target than a continuously moving belt. The carrier stops and holds a fixed position at each station.

How a Robot Locates a Moving Workpiece Carrier

Robot conveyor tracking relies on two data sources working together. First, an encoder on the drive shaft reports conveyor position. The robot controller uses this count to predict each carrier's location. Second, a vision system on a fixed camera confirms the actual carrier position. In addition, the camera corrects for chain stretch or slack. Encoder-only tracking has a known weak point here. In fact, a widely cited industrial automation patent describes the problem directly. Backlash in drive motors, couplings, and chain assemblies commonly produces position errors of several hundred millimeters on long conveyor runs. Vision correction closes this gap. A 2020 Sensors journal study on optical robot tracking reported a real result. Specifically, position accuracy reached plus or minus 0.35 mm, and orientation accuracy reached plus or minus 0.07 degrees. This accuracy came from an optical tracking system feeding correction data back to the robot controller.

Communication Between the Robot Controller and the Conveyor PLC

A robot cannot collaborate with a circular conveyor line without a shared communication channel. This channel connects the robot controller to the conveyor PLC directly. In practice, the PLC reports station status, carrier presence, and index position on a fixed cycle. The robot controller, in turn, sends ready and complete signals back. The conveyor only advances once the robot finishes the task at the current station. For example, ABB's conveyor tracking module illustrates the scale this reaches in a working plant. One module connects up to 4 robots, 4 conveyors, and 8 cameras. In addition, the platform scales up to 40 robots across 16 conveyors in one coordinated system. This kind of scalable architecture keeps every station synchronized as the line grows.

Matching Robot Reach and Cycle Time to Station Spacing

Station spacing on a multi station conveyor sets a hard limit on robot choice. A robot with a short reach needs a tighter station interval. By comparison, a robot with a longer reach and a faster cycle time can work stations spaced further apart. Furthermore, the robot's cycle time must fit inside the index dwell time. Otherwise, the carrier moves on too soon, and the task stays unfinished. Engineers size the rotary indexing table dwell period around the slowest station on the loop. Every other station waits on this single station. This is why a pick and place robot on a light assembly task usually sits at a different index interval. Instead, a heavier robot performing a press or screw task usually needs a longer dwell.

Safety Methods for Working Near the Conveyor with Robot Integration

Collaborative robot work beside a circular conveyor line follows four defined methods. These methods come from ISO 10218 and ISO/TS 15066 together. First, safety-rated monitored stop halts the robot the instant a person enters the zone. Second, hand guiding lets an operator move the robot directly during setup. Third, speed and separation monitoring slows the robot as a person approaches. This method uses live sensor data instead of a fixed stop. In addition, power and force limiting caps contact force below an injury threshold. This limit allows some fenceless operation next to the conveyor. Most conveyor-side cells combine two of these methods together. In fact, a fast pick and place task rarely stays within force-limited speed the whole time.

A Practical Integration Reference Table

The table below compares common integration approaches for pairing a robot with a circular conveyor line. In short, each row groups a tracking method with its typical collaboration mode.

Tracking Method

Typical Collaboration Mode Position Accuracy Communication Link Best-Fit Application

Governing Standard

Encoder-only tracking Speed and separation monitoring Several hundred mm (uncorrected) PLC pulse count to robot controller Long straight conveyor runs ISO 10218 Encoder plus vision correction Power and force limiting (light tasks) ±0.35 mm / ±0.07° Camera link plus PLC encoder feed Pick and place on a moving belt ISO/TS 15066 Fixed indexing, no tracking needed Safety-rated monitored stop Carrier fully stopped at station Discrete I/O, station-ready signal Multi station assembly, screw driving ISO 10218-2 TallMan Robotics precision circular conveyor track Hand guiding for setup, monitored stop in production ±0.02 mm servo tolerance PLC index position to robot controller Screw-machine-integrated assembly line ISO 10218 / TallMan spec

A Real Integration Case of Conveyor with Robot Integration

TallMan Robotics documents a multi station circular conveyor built for a robotic assembly line. The system pairs directly with an automatic screw machine on site. Specifically, the circular track carries workpieces through loading, screw driving, and inspection stations arranged around the circumference. The robot controller reads each station's index position from the conveyor first. Then, it starts the assigned task at the current station. The same platform holds a servo positioning tolerance of plus or minus 0.02 mm on the closed-loop track. As a result, this tolerance keeps the workpiece aligned within the robot's repeatability band at every station. In short, mechanical precision and robot coordination work as one system, not two designs bolted together.

Putting Robot Collaboration Into Practice