How to calculate the Gripper's vertical motion on 2F85 / 2F140?

Context

Robotiq’s 2F‑85 and 2F‑140 adaptive grippers use a circular linkage mechanism that results in vertical displacement as the fingers open and close. This motion can impact applications where vertical precision is essential—for example:

• Inserting objects into tight enclosures

• Avoiding collisions with parts or fixtures

• Synchronizing gripper movement with robot paths

This article explains how to estimate the vertical shift based on the gripper's position value (0 to 255).

1. Vertical Displacement and Position Reference

• Position = 0: Fully opened gripper → 0 mm vertical displacement (baseline reference)

• Position = 255: Fully closed gripper → Maximum vertical displacement (depends on gripper model)

As the gripper closes, the circular mechanism causes the fingers to rotate inward and upward, increasing the effective vertical height of the gripper tip.

2. Approximate Calculation Formula

To estimate the vertical displacement for any position value:

• Max Height: This value depends on the gripper model (2F‑85 or 2F‑140). Consult the technical drawings for precise values.

• This formula assumes a roughly linear behavior for estimation purposes. For high-precision tasks, use measured data or the motion graph.

3. Technical Drawings and Reference

For exact displacement values at specific positions, refer to the gripper’s technical documentation:

• See Section 6.1 – Specifications of the 2F‑85 & 2F‑140 Instruction Manual

These diagrams provide open and closed dimensions that can be used to verify actual height changes.

Conclusion

The 2F‑85 and 2F‑140 grippers exhibit vertical motion during closing due to their mechanical design. Use the position-based formula and motion graph to estimate this shift for motion planning. When needed, refer to exact technical drawings for dimensionally accurate applications.