Robot-wrist gripper design review
A documented revision of the selected generated four-bar: 50 mm exposed fingers, an enclosed common drive and a tool-side mating interface based on the official UR5e flange drawing.
Not released for manufacture. Finger peak stress is not converged, and physical gripping and installation tests remain open.
1. Keep the original mechanism; record the revision
The original METHEUS Generate session produced 300 kinematic candidates: 167 feasible, 16 failing and 117 unconfirmed. Original four-bar, six-bar and passive-slider exports were compared. This revision retains four-bar index 93 / rank 94 from that session; it does not claim a new Generate run.
The original 54-word input was followed by recovery requests, connected detailed-design work, the 36-word finger/flange revision, and a further 127-word review request. The app responses were checked and corrected through the METHEUS/FreeCAD connection before the final model was recorded.
Read the exact prompt and review sequence
2. Detail the longer fingers and mounting interface
Exposed reach is measured from the front-cover plane Z = 32 mm to the tip at Z = 82 mm. This increases exposed reach from 25 to 50 mm; pad length increases from 23 to 48 mm. Original mounting feet, shank sections, local motion frames and generated joint coordinates are retained.
The official robot flange has four M6 holes on a 50 mm pitch circle, a 31.50 H7 female recess and a 6 H7 locating hole. The tool model uses a 31.48 × 2 mm male pilot and a 6.10 × 8.00 mm radial locating slot. Modeled screw penetration is 7 mm against the documented 8 mm limit. Actual fits, pin retention, supplier tolerances, tightening torque and installation access still require physical review.
No unintended interference was detected in the documented 72 sampled poses or 26 mounting checks. Finite samples do not certify continuous collision freedom, manufacturing tolerance or deformation clearance. The approximately 0.02 mm journal fit is an intentional pin/bore clearance.
3. Review finger bending separately from drive torque
| Reviewed result | Scope |
|---|---|
| Right 21.479 MPa / 0.05197 mm | Actual right finger, fixed foot, 0.8 mm mesh |
| Left 19.593 MPa / 0.03931 mm | Actual left finger, fixed foot, 0.8 mm mesh |
| Displacement stable; stress not converged | Last refinement: displacement +0.11–0.13%; raw peak stress +10.45–15.74% |
| 2.301 N·m motor demand | Separate rigid-body calculation at 85% assumed efficiency; 2.5 N·m rated motor |
Each finger FEM case applies 25 N normal load and the entire 7.405 N tangential load at the aluminium tip. Attachment compliance, pad contact, eccentric torsion and fatigue are excluded. The earlier three-plate MFBD remains historical; it does not validate this complete revised gripper.
4. Deliver the model-derived documents
Model-derived BOM: 97 physical instances in 36 groups. The 1.032 kg estimate uses modeled volume, assigned densities and recorded catalogue masses; it is not a weighed prototype.
5. Next engineering checks
- Model production fillets and check stress convergence.
- Verify mounting-foot screws, carrier and assembly compliance.
- Verify pad contact, friction, adhesive/bond retention and physical payload capacity.
- Verify fatigue, impact, thermal effects and duty cycle.
- Verify actual UR5e fit, tolerances, locating-pin retention and installation torque.
Execution and reproducibility
GPT-5.6 Luna / medium / Basic handled the recorded app requests. GPT-6 Astra / Ultra performed connected recovery, detailed design, correction and engineering review. The final assembly is not the automatic result of one prompt. Models, settings, conversation history and search results can alter candidate geometry and ranking.
Execution record