How To Ensure The Stopping Accuracy of Circular Pallet Conveyor at Different Workstations?

Circular Pallet Conveyor is an automated material handling system that transports pallets or fixtures in a continuous loop to carry components between workstations for assembly or manufacturing. Its closed-track design optimizes floor space while enabling high-speed, repetitive operations. Ensuring precise stopping accuracy at different stations is critical, typically achieved through a dual-positioning strategy combining sensors for coarse positioning and mechanical shot pins or clamps for fine alignment. TallMan Robotics specializes in these systems, utilizing advanced servo control and encoder feedback to compensate for mechanical wear, such as chain stretching, ensuring consistent repeatability. This guarantees reliable performance in precision tasks like automated assembly and inspection.

How To Ensure The Stopping Accuracy of Circular Pallet Conveyor at Different Workstations?

In response to the high-precision stopping requirements of the Circular Pallet Conveyor at different workstations, and based on TallMan Robotics’s practical experience in precision motion control, the following are the core technical strategies and solutions for achieving high repeatability positioning accuracy:

Core Technology Strategy: Composite Positioning in Circular Conveyor System .

Relying solely on the semi closed loop control of the motor encoder cannot eliminate the errors caused by mechanical transmission (such as chain stretching and belt slippage). TallMan Robotics  recommends using a dual composite strategy of “coarse positioning+fine positioning”, combined with sensors and mechanical hard limits, to ensure that the stopping accuracy of each workstation in Circular Pallet Conveyor can reach ± 0.1mm or even higher.

Specific implementation plan in Circular Conveyor System.

1. Primary positioning: proximity switch+encoder collaboration

Function: To achieve rapid and flexible initial stopping, reducing the impact of precision positioning mechanisms.
Principle:
Proximity sensor: Install proximity switches (or photoelectric sensors) in front of each workstation for Circular Pallet Conveyor, and send a position pre signal to the PLC when the tray passes by.
Encoder: The main drive motor of the conveyor line is equipped with a high-resolution encoder. After receiving the sensor signal, the PLC does not immediately stop, but controls the motor to decelerate accurately based on the feedback pulse number from the encoder.
Advantages: Solves the problem of inconsistent stopping positions caused by dimensional tolerances or sliding of different trays, ensuring that the trays enter the precise positioning capture range every time.

2. Precise positioning: mechanical/pneumatic positioning mechanism

After the tray is roughly positioned into the work area through sensors and encoders, the physical locking mechanism of Circular Pallet Conveyor is activated for secondary precise positioning.

Shot Pin:
Action: There is a precision liner at the bottom of the tray, and the positioning pin is raised from below and inserted into Circular Pallet Conveyor.
Accuracy: can reach ± 0.05mm.
Applicable: Workstations that require extremely high precision assembly (such as pressing, tightening).
Lateral clamping/blocking device:
Action: Use a buffer stopper to stop the tray, and at the same time, push the V-shaped block or flat plate out of the lateral cylinder to push the tray towards the fixed reference surface.
Advantages: Eliminating radial clearance of trays on the track of Circular Pallet Conveyor.

3. Dynamic compensation and rebound prevention

Servo control algorithm: TallMan Robotics integrates special acceleration and deceleration curves in the control system for Circular Pallet Conveyor. When approaching the positioning point, the torque control of the servo motor is used to ensure a smooth fit of the tray with the positioning mechanism, preventing rebound caused by impact.
Multiple confirmations: After the precise positioning mechanism of Circular Pallet Conveyor is activated, an independent confirmation sensor (such as a magnetic switch or micro switch) feeds back a “in place locking” signal before allowing the robot or operator to proceed to the next step of the operation.

TallMan Robotics Limited’s Integration Solution.

To ensure the long-term effectiveness of the above strategies, TallMan Robotics Limited emphasizes the following two points in its design and implementation of Circular Pallet Conveyor:

1. Eliminating cumulative errors:

For the closure characteristics of the circular line of Circular Pallet Conveyor, dual drive synchronous control  (dual servo motor drive) is adopted, combined with  real-time tension monitoring, to prevent long-distance cumulative errors caused by chain stretching.

2. Thermal expansion compensation:

In environments with long distances or large temperature differences, there may be thermal expansion and contraction of the guide rail and tray materials in Circular Pallet Conveyor. TallMan Robotics optimizes the design of the positioning mechanism (such as using flexible floating joints) to allow the tray to adapt within a certain range, ensuring that the positioning pin does not get stuck due to thermal deformation.

Through the composite positioning scheme of “soft hard combination and dual locking” mentioned above, even under high-speed continuous operation, TallMan Robotics can ensure the long-term stability of the stopping accuracy of each workstation in a Circular Pallet Conveyor, providing reliable guarantee for precision automated assembly lines.

Youtube: https://www.youtube.com/@tallmanrobotics 

Tiktok: https://www.tiktok.com/@tallmanrobotics

Facebook: https://www.facebook.com/tallmanrobotics

Linkedin: https://www.linkedin.com/in/tallman-robotics