---
kind: concept
slug: in-hand-manipulation
title: In-hand manipulation
summary: >-
  Changing an object's pose while a gripper, palm or finger holds or lifts it, without putting it down. Four mechanisms: tilting a large object against supports, a suction palm with belts, tape-spring arms that roll and convey, and vibration on a parallel gripper. Author-reported, on different setups.
tags: [manipulation, grasping, in-hand, soft-robotics, vibration]
papers: ["2411.16055", "2411.17124", "2412.00268", "2412.14899"]
related: [robotic-grasp-generation, teleoperation]
status: draft
updated_at: 2026-10-25
---

## Overview

In-hand manipulation changes an object's pose while a hand, palm or finger
still holds or lifts it. The arm then does not have to put the object down and
regrasp it [arxiv:2411.17124 §I]. Four cards cover it so far, and they do not
share one scope. One picks up an object too large to grasp, starting from a
table [arxiv:2411.16055 §I]. One reorients a thin object inside the grip of a
parallel gripper [arxiv:2412.14899 §1]. The other two move an object within a
soft or deployable hand's own workspace [arxiv:2411.17124 §III-A]
[arxiv:2412.00268 §Demonstrations].

The shared difficulty is that the actuator does not control every degree of
freedom of the object directly. The object moves through friction, gravity or
a support it rests on. The vibration method is underactuated: one steering
input cannot control both orientation and position, so orientation has to be
set first [arxiv:2412.14899 §4]. The tilt method keeps the object from sliding
away by contact with a table, a support and the palm [arxiv:2411.16055 §III].

## Variants

### Tilt a large object against supports

A curved palm presses an object up against an inclined second support while
the object rests on a first one. The palm then turns under the object and
lifts it, so the object is held between the palm and the table [arxiv:2411.16055
§V]. The paper gives two tilt modes. The motion-force mode, in which one motor
follows an angle and the other holds a torque, is described as gentler and as
needing fewer commands [arxiv:2411.16055 §V-B].

On a two-motor palm, the yoga block succeeded 5 of 5 times in both modes, and
the beverage container succeeded 4 of 5 times in motion mode and 5 of 5 in
motion-force mode [arxiv:2411.16055 fig. 6c]. On a UR3 arm with a rigid palm,
a steel box failed 0 of 5 at a 90-degree support angle and succeeded 5 of 5 at
61 degrees [arxiv:2411.16055 tab. I]. The tests are teleoperated or
programmed, open-loop and without a force/torque sensor [arxiv:2411.16055 §V-A]
[§V-D]. Card: [Picking by Tilting](/papers/2411.16055).

### Suction palm with belt surfaces

DexGrip combines three soft Fin Ray fingers, each with a belt that moves the
object along it, and a palm with a telescoping arm and a rotating suction cup
[arxiv:2411.17124 §III-A]. In a palm test on 12 objects, 10 adhered and 9
succeeded overall, counting adhesion, repositioning and twisting [arxiv:2411.17124
tab. II]. The pear pivot and the cube face flip are shown, but only by eye
[arxiv:2411.17124 §IV-C] [§IV-D]. Its suction model gives a maximum mass, but
the accelerations and friction it needs are not stated [arxiv:2411.17124 eq. 3]
[eq. 4]. Card: [DexGrip](/papers/2411.17124).

### Tape-spring arms that roll and convey

GRIP-tape has two arms, each made of two spring-steel tape-measure strips bonded
together, driven by seven motors [arxiv:2412.00268 §Design] [p. S2]. Moving the
arms in the same direction rolls an object in place, and moving them in opposite
directions carries it toward the base [arxiv:2412.00268 §Demonstrations]. A
load cell in the base gives a tip-force estimate, and a 0.25 N contact threshold
drives automatic gripping [arxiv:2412.00268 §Sensing] [§Automatic]. Closed-loop
grip-width control keeps an ellipse in the grip, while open loop drops it
[arxiv:2412.00268 §Feedback] [fig. 8]. Open-loop rotation works only for round
objects [arxiv:2412.00268 §Feedback]. Card: [Grasping and Rolling In-plane
Manipulation Using Deployable Tape spring Appendages](/papers/2412.00268).

### Vibration on a parallel gripper

An eccentric-mass motor on one finger shakes a thin object. Steering the
vibration moves the object's centre of mass around the grip point, which turns
the object. A radial move then sets the position [arxiv:2412.14899 §2.2.4]
[§2.3.4]. Duty-cycle vibration (50%) during translation lowered the disk's
orientation error to 1.5 ± 1.02 degrees, against 3.8 ± 1.2 degrees for a
constant frequency. The plate gave 2.7 against 4.5 degrees [arxiv:2412.14899
tab. 1]. Position error with the duty cycle was about 1.9 mm on both test
objects [arxiv:2412.14899 tab. 1]. Over 10 trials per object, the credit card
succeeded in 100% of tasks, the cellphone 90% and the steel ruler 70%
[arxiv:2412.14899 tab. 2]. The pose comes from ArUco markers at 60 Hz
[arxiv:2412.14899 §3.2]. Card: [Vibration-based Full State In-Hand Manipulation
of Thin Objects](/papers/2412.14899).

## When to use which

| Situation | Use | Why |
|---|---|---|
| Object too big for the fingers, with a table and an incline or wall nearby, and no force sensing | Tilt against supports | Needs only the environment and a palm; the card's open-loop tests reach 4 to 5 of 5 on the 2-DOF palm [arxiv:2411.16055 fig. 6c] |
| Object with a face a suction cup can seal, and a palm with its own motor | Suction palm with belts | The only card that combines suction with belt surfaces; mass limits are a model, not measured [arxiv:2411.17124 eq. 3] |
| Round object, planar task, long arms are acceptable | Tape-spring arms | Rolling and conveyance are shown; force feedback is possible through the base [arxiv:2412.00268 §Feedback] |
| Thin object in a parallel gripper, and a motor and a pose sensor can be added | Vibration | The only card with a measured orientation error on a thin object; the thinnest test object is 0.76 mm [arxiv:2412.14899 tab. 2] |

Every number here comes from a different setup, object and trial count. Use
the table to pick a family, not to rank the variants.

## Implementation sketch

The vibration variant, which is the most specified. Its order is orientation
first, then position, with the pose read from markers at 60 Hz.

```pseudocode
# Orient first, then translate, with pose feedback  [arxiv:2412.14899 alg. 1]
# Input:  goal (r_g, phi_g, psi_g) in mm and degrees; pose from ArUco [§3.2]
# Output: |r - r_g| <= 1 mm and |psi - psi_g| <= 1 degree  [§3.2]

def manipulate_in_hand(goal, eps_r=1.0, eps_psi=1.0):
    # Move the centre of mass to the origin with duty-cycle vibration  [alg. 1]
    while abs(r) > eps_r:
        steer(pi)                  # theta = +-pi; sign not stated  [§2.2.4]
        duty_cycle_vibrate(50)     # Omega(t) at 50%  [§3.2]
    # Give the object a kick to start rotating about a non-zero radius  [§3.2]
    set_orbit_radius(r_c)          # r_c from the per-object limits  [tab. 2]
    kick(theta_kick, dt=0.1)       # theta_kick in [pi/6, pi/4]  [§3.2]
    # Rotate until the angle error is within tolerance  [alg. 1]
    while abs(psi - psi_g) > eps_psi:
        steer(pi)
        vibrate(168)               # constant frequency in rotation  [§3.2]
    # Return to the origin, then move radially to the goal position  [alg. 1]
    return_to_origin(eps_r)
    translate_radially(r_g, phi_g, eps_r)
```

The tape-spring arms do not follow this order. They roll and convey in one
motion [arxiv:2412.00268 §Demonstrations].

## Contradictions

- **Slender objects.** The tilt paper says slender objects tilt more easily
  [arxiv:2411.16055 §IV-A]. The vibration paper says the steel ruler, the
  narrowest object it tested, succeeded least often (70%), because its narrow
  shape and small orbit radius make it drop during the orbit [arxiv:2412.14899
  §3.3]. The mechanisms differ, and neither paper tests the other's claim.
- **Friction.** The tilt paper attributes the palm's stability to high palm
  friction [arxiv:2411.16055 §V-D]. It plans with friction values of 0.1 and
  0.2 at that contact, and the hardware's real values are not stated
  [arxiv:2411.16055 fig. 3]. The tape-spring paper names belt-to-finger friction
  as a limit [arxiv:2412.00268 §V] and does not measure it.
- **Rotation range.** The suction-palm paper's abstract claims full 360-degree
  rotation about all three axes. Its palm rotates about one axis, and the paper
  reports no angle range per axis [arxiv:2411.17124 §IV-B].
- **Measures.** No two papers report the same quantity. Orientation error is in
  degrees for the vibration paper [arxiv:2412.14899 tab. 1] and tip error in mm
  for the tape-spring paper [arxiv:2412.00268 §Kinematics]. Success counts use
  different objects and trial counts in each card.

## Papers

- [Picking by Tilting: In-Hand Manipulation for Object Picking using Effector with Curved Form](/papers/2411.16055): tilts a large object against two supports, then tucks a curved palm under it.
- [DexGrip: Multi-modal Soft Gripper with Dexterous Grasping and In-hand Manipulation Capacity](/papers/2411.17124): soft gripper with belt-driven fingers and a telescoping suction palm.
- [Grasping and Rolling In-plane Manipulation Using Deployable Tape spring Appendages](/papers/2412.00268): two tape-spring arms that roll and convey objects in a plane.
- [Vibration-based Full State In-Hand Manipulation of Thin Objects](/papers/2412.14899): an eccentric-mass motor on one finger sets position and orientation of thin objects.