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Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Mon Oct 20, 2025 6:21 am
by williams84
Speaking from personal experience here,
Object occlusion by the robot's own hand during the final approach to a grasp is a common and annoying perception problem - the closer the hand gets to a good grasp position, the more it blocks the camera's view of exactly what it's about to grab.
Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Mon Oct 20, 2025 8:50 pm
by ivan22
@williams84 Thanks for laying this out, genuinely useful.
A lot of the manipulation shown in production demos still leans heavily on teleoperation, particularly for anything involving fine force control or novel objects - autonomous grasp success rates on genuinely unstructured, previously-unseen clutter are still well below what teleoperation can achieve. In-hand reorientation (repositioning a grasped object without setting it down) is one of the more advanced manipulation skills, requiring either a highly dexterous hand with enough DoF or clever use of gravity and controlled slipping - it's an active research area rather than a solved problem.
Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Mon Oct 20, 2025 11:58 pm
by chenperez
Same conclusion I've come to. Also worth noting:
Grasp planning for deformable or non-rigid objects (bags, cables, cloth) remains one of the genuinely unsolved problems in manipulation - rigid-body grasp models simply don't capture how the object will behave once contact starts.
Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Sat Oct 25, 2025 6:42 am
by gimbalmar65
Genuinely curious -
Vision-based grasp confidence estimation (predicting success before attempting a grasp) and tactile-based confirmation (confirming after contact) are complementary rather than competing - vision helps you choose a grasp, tactile tells you if it actually worked.
Reminds me a bit of the early drone hobbyist scene, honestly.
Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Tue Oct 28, 2025 10:36 pm
by betty.king
Short answer:
Palm sensing gets less attention than fingertip sensing, but a lot of power grasps (holding a box, a tool handle) rely more on palm and lateral finger contact than fingertip contact, so under-sensing the palm can leave a real blind spot in grasp confidence. Payload-to-hand-weight ratio varies a lot across current dexterous hands, and it's a meaningful tradeoff - more DoF and finer sensing generally means more actuators and mass in the hand itself, which eats into the arm's usable payload budget.
Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Fri Oct 31, 2025 3:39 am
by young56
Can I ask a dumb follow-up -
Figure's fourth-generation Dexterous Hand (on Figure 02/03) reportedly offers 16 degrees of freedom per hand with sensors integrated into each finger, aimed at fine force control tasks like handling small electronic components without crushing them.
Reminds me a bit of the early drone hobbyist scene, honestly.
Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Fri Nov 07, 2025 2:24 pm
by scott21
Here's what I know on this:
Cable routing through a wrist joint with multiple degrees of freedom is a genuinely tricky mechanical design problem - tendons and wiring both need enough slack to avoid binding through the full range of motion without tangling or fraying over thousands of cycles.
Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Fri Nov 14, 2025 8:13 am
by ssantos
@scott21 Slight correction, though the overall point stands:
Vision-based grasp confidence estimation (predicting success before attempting a grasp) and tactile-based confirmation (confirming after contact) are complementary rather than competing - vision helps you choose a grasp, tactile tells you if it actually worked.
This whole thread is a good reminder how young this field still is.
Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Sun Nov 16, 2025 12:05 pm
by barbara.jones
@ssantos Worth being a little skeptical of the marketing angle here.
Wet, oily, or otherwise low-friction objects are still a genuine edge case for most current hands, since tactile sensing and grasp-force controllers are typically tuned and validated on dry, higher-friction test objects.
Re: 3-finger vs 5-finger designs - when does the extra finger actually pay off?
Posted: Mon Nov 17, 2025 9:25 am
by sarah.santos3
@barbara.jones Slightly off-topic, but related:
Imitation learning from human demonstration video (without robot teleoperation data) is an appealing way to scale up training data cheaply, but it runs into the embodiment gap - human hand kinematics and force profiles don't map directly onto a robot hand's very different mechanism. Compliant wrists that absorb impact during a bad approach or misjudged contact reduce mechanical stress on the whole arm, which matters a lot for long-term reliability even though it's a less visible feature than the hand itself.