Nonprehensile Manipulation Research Articles

Kinematic Trajectory Planning for Dynamically Unconstrained Nonprehensile Joints

This letter considers an augmented kinematic formulation for nonprehensile manipulation through intermittent contacts as occurring in catching, batting, or juggling. In such scenarios, the contact point with an end-effector is variable, which we propose to model with additional virtual joints at the end of the kinematic chain. While not in contact with the manipulated part, these new joints are unconstrained in terms of velocity and acceleration. An optimization based and, thus, tuning-free comparison of differential inverse kinematic approaches is carried out, given path or trajectory of the manipulation task is known. Simulations and an experiment show that the proposed augmentation enables dynamically feasible acceleration variations at high velocities on and close to a given path.

Nonprehensile Manipulation of an Underactuated Mechanical System With Second-Order Nonholonomic Constraints: The Robotic Hula-Hoop

A mechanical system consisting of a hoop and a pole is considered, for which the corresponding dynamic model represents an underactuated system subject to second-order nonholonomic constraints. The pursued goal is to simultaneously track a trajectory in the unactuated coordinates and to stabilize the actuated ones. For the model under consideration, the well-known noncollocated partial feedback linearization algorithm fails since the corresponding zero dynamics is unstable. In this work, we show that the actuated coordinates, i.e., the pole can be stabilized by exploiting the null space of the coupling inertia matrix without affecting the performance in the underactuated coordinates tracking. We present a formal mathematical analysis, which guarantees ultimate boundedness of all coordinates. Performed simulations bolster the proposed approach.

1-Actuator 3-DOF Manipulation Using an Underactuated Mechanism with Multiple Viscoelastic Joints

This paper discusses a dynamic nonprehensile manipulation by using a vibrating plate. The manipulation method, where 3-DoF (degrees of freedom) position and orientation of the object on the plate surface is controlled by a single actuator, is proposed. First, we introduce an underactuated mechanism with one active joint and multiple viscoelastic passive joints. This mechanism is characterized in that all joints are set to be nonparallel. Via a numerical example, it is revealed that not only the shape of the plate vibrational orbit but also the rotational direction can be changed by the input frequency of the active joint. Finally, we show experimental results using a prototype for confirming the feasibility of the proposed method.

Vision and force/torque integration for realtime estimation of fast-moving object under intermittent contacts

This paper considers the fast and accurate estimation of motion variables of a rigid body object whose movement occurs from intermittent contacts with coordinating manipulators in nonprehensile manipulation tasks. The estimator operates under multiple sensory data including visual, joint torque, joint position and/or tactile measurements which are combined at the lower level to compensate for the latency and the slow sampling of the visual data. The estimator is real-time in the sense that it provides the motion data of the target object at the same fast sample rate of the servo controller without delay. The basic formulation is the multi-rate Kalman filter with the contact force vector as its process input, and the visual observation as its measurement output signal which is the down-sampled and delayed version of the configuration of the target object. Experimental tests are conducted for the case of planar object manipulation as well as the non-centroidal rotation under gravity using a robotic hand, and their results are presented to demonstrate the validity of the proposed estimation scheme.

Passive Non-Prehensile Manipulation on Helix Path Based on Mechanical Intelligence

Passive Non-Prehensile Manipulation on Helix Path Based on Mechanical Intelligence

Passive Non-Prehensile Manipulation on Helix Path Based on Mechanical Intelligence

Passive Non-Prehensile Manipulation on Helix Path Based on Mechanical Intelligence

Passive Non-Prehensile Manipulation on Helix Path Based on Mechanical Intelligence

Passive Non-Prehensile Manipulation on Helix Path Based on Mechanical Intelligence

Non-prehensile manipulation planning of a three-rigid-link object using two cooperative robot arms

This work presents the dynamic modelling, the static analysis, and a proposed control algorithm for non-prehensile manipulation of a three rigid link object manipulated by two cooperative robot arms in a plane. The system is configured so that one arm is in contact with two links, while the other arm is in contact with the third link. The purpose of the static analysis is to obtain the interaction forces as well as their locations required to hold the object for a specified configuration. The dynamic model of the system is introduced, and the static analysis, considering both the frictionless and frictional contact cases, is deduced. The effect of changing the direction of the static frictional forces at the multi contact points on the static problem is introduced. A PD controller with feed forward acceleration is proposed to perform the manipulation task. Simulation results show the validity of the proposed control scheme.

The Effect of Shapes in Input-State Linearization for Stabilization of Nonprehensile Planar Rolling Dynamic Manipulation

A control framework for nonprehensile planar rolling dynamic manipulation is derived in this letter. By rotating around the center of mass, the manipulator moves a part without grasping it but exploiting its dynamics. Given some assumptions on the shapes of both the object and the manipulator, a state transformation is found rendering the state-space system in a chain of integrators form without internal dynamics, allowing the possibility to exploit linear controls to stabilize the whole system. An analysis of the differential flatness property of the system is also provided. Simulations and experiments validate the derived framework.

非平行型能動・受動ハイブリッド関節を用いた1アクチュエータ3自由度マニピュレーション

This paper discusses a dynamic nonprehensile manipulation by using a vibrating plate. The manipulation method, where three-DOF (degrees of freedom) motion of an object on the plate is controlled by a single actuator, is proposed. For the vibration mechanism, we utilize the active-passive hybrid joint whose two axes are arranged in nonparallel to each other. This mechanism features the variable plate trajectory with respect to the input frequency. Focusing on the motions of multiple mass points on the plate, we investigate the jumping velocity distribution with respect to the input parameters, the frequency and the offset angle, of the single actuator. Through the observation of the characteristics of the distribution, we reveal that three-DOF motion of the object, namely the position and orientation, can be controlled by the input parameters. Finally, we show experimetal results for confirming the feasibility of the proposed method.

非平行型能動・受動ハイブリッド関節を用いた非把持ダイナミックマニピュレーション

This paper discusses a dynamic nonprehensile manipulation by using a vibrating plate. The manipulation method, where two DOF (degrees of freedom) motion of an object on the plate surface is controlled by a single active joint, is proposed. For the plate vibration mechanism, we newly introduce an active-passive hybrid joint whose two axes are arranged in nonparallel to each other. This mechanism features the plate vibration trajectory is variable based on the input frequency. We then analytically derive the trajectory of object on the vibrating plate. Through this analysis, we reveal that two DOF motion of the object can be controlled by utilizing the variable vibration effect. Finally, we show experimental result by using the prototype robot, for confirming the validity of the proposed method.

1P2-D07 関節軸非平行型劣駆動マニピュレータによる非把持全方位マニピュレーション

This paper discusses a dynamic nonprehensile manipulation by using a vibrating plate. The omnidirectional manipulation for an object on the plate surface by a single active joint, is proposed. For the plate vibration mechanism, we introduce the nonparallel type active-passive hybrid joint with viscoelasticity. We show that the omnidirectional manipulation can be achieved by controlling three input parameters of the active joint: the frequency, the amplitude, and the offset angle. After showing the relationship between three control parameters and the object's translational velocity, we further discuss the optimum design parameters, including the viscoelasticity of the passive joint. Finally, we show experimental result by using the prototype robot, for confirming the validity of the proposed method.

3P1-V02 能動・受動複合関節の振動方向可変効果を利用した非把持マニピュレーション(フレキシブルロボット・メカニズム)

This paper discusses a dynamic nonprehensile manipulation by using a vibrating plate. The manipulation method, where 2-DOF (degrees of freedom) translational motion of a object on the plate surface is controlled by a single active joint, is proposed. For the plate vibration mechanism, we first introduce the active-passive hybrid joint with viscoelasticity. This mechanism features that the plate vibration direction is variable based on the input frequency of the active joint. We then analytically derive the trajectory of the object on the vibrating plate. Through this analysis, we reveal that 2-DOF translational motion of the object can be controlled by using the variable vibration direction. After showing the relationship between the viscoelasticity of the passive joint and the object's translational velocity, we further discuss the optimum design parameter. Finally, we show experimental result by using the prototype robot, for confirming the validity of the proposed method.

Characterization of Deformable Objects by Using Dynamic Nonprehensile Manipulation

This paper presents amethod for evaluating a physical parameter of unknown deformable objects, by using nonprehensile manipulation. By means of simulation analysis, we show that the curve representing the relationship between the object’s angular velocity and the plate’s frequency has a resonance-like response. Based on the above phenomenon, we utilize a Lorentz curve fitting to represent the object’s angular velocity as a function of the plate’s frequency with a simple mathematical expression, instead of deriving the equation of motion of the system that is rather complex due to the intricate dynamics of the system. Then, we show that the first order natural angular frequency in bending determines the frequency at which the object’s has its maximal angular velocity. Using this information, we present a method of how to estimate the object’s first order natural frequency in bending. We show the simulation and experimental results to verify the validity of the method presented.

PRI (PALM ROTATION INDICATOR): A METRIC FOR POSTURAL STABILITY IN DYNAMIC NONPREHENSILE MANIPULATION

In this study, we discuss the postural stability of a nonprehensile manipulation problem, which deals with multibody objects. As a metric for postural stability, we define PRI. Then, the system is posturally stable, if PRI is inside the convex hull of the object-manipulator contact surface. We then discuss that dynamic biped locomotion is a special case of dynamic nonprehensile manipulation in all aspects; we prove that ZMP (zero-moment point) and FRI (zoot rotation indicator) are special cases of PRI (palm rotation indicator). Simulations and experiments corresponding to simple examples support the results.DOI: http://dx.doi.org/10.5755/j01.mech.18.4.2324

A Planning Framework for Non-Prehensile Manipulation under Clutter and Uncertainty

Robotic manipulation systems suffer from two main problems in unstructured human environments: uncertainty and clutter. We introduce a planning framework addressing these two issues. The framework plans rearrangement of clutter using non-prehensile actions, such as pushing. Pushing actions are also used to manipulate object pose uncertainty. The framework uses an action library that is derived analytically from the mechanics of pushing and is provably conservative. The framework reduces the problem to one of combinatorial search, and demonstrates planning times on the order of seconds. With the extra functionality, our planner succeeds where traditional grasp planners fail, and works under high uncertainty by utilizing the funneling effect of pushing. We demonstrate our results with experiments in simulation and on HERB, a robotic platform developed at the Personal Robotics Lab at Carnegie Mellon University.

Dynamic Nonprehensile Manipulation for Rotating a Thin Deformable Object: An Analogy to Bipedal Gaits

A rigid plate end-effector at the tip of a high-speed manipulator can remotely manipulate an object without grasping it. This paper discusses a dynamic nonprehensile manipulation strategy to rotate thin deformable objects on a rigid plate with two degrees of freedom (DOFs). The deformation of the object due to dynamic effects is exploited to produce fast and stable rotation. By varying the frequency of the rotational component of the plate's motion, we show that the dynamic behavior of the object mimics either a sliding, walking, or running gait of a biped. We introduce a model to simulate this type of system in which the object is constructed of multiple nodes that are connected by viscoelastic joint units with three DOFs. The joint's viscoelastic parameters are estimated experimentally in order to model real food. Afterward, simulation analysis is used to investigate how the object's rotational behavior and its angular velocity change with respect to the plate's motion frequency. We show how the object's behavior during rotation is analogous to bipedal sliding, walking, and running gaits and then obtain optimal plate motions leading to the maximal angular velocity of the object. We also reveal that an appropriate angular acceleration of the plate is essential for a dynamically stable and fast object's rotation. We further show that the friction coefficient that maximizes the object's angular velocity depends on its gait.

2A1-K04 非把持形態によるレオロジー物体の変形制御(フレキシブルロボット・メカニズム)

2A1-K04 非把持形態によるレオロジー物体の変形制御(フレキシブルロボット・メカニズム)

Fuzzy Nonprehensile Manipulation Control of a Two-Rigid-Link Object by Two Cooperative Arms

AbstractMotivated by the application of robots in holding and/or transferring a patient, this paper introduces the nonprehensile manipulation control algorithm for lifting up (or lowering down) a two-rigid link object with a passive joint applying two cooperative arms in a two-dimensional space. Fuzzy technique is applied for manipulation control, with high friction at contact, as it is very difficult to be done by conventional model based methods. A fuzzy controller is designed for every variable of the four dimensional position vector specifying the joint's position and links’ orientations. A rule of a fuzzy controller would be like a human would do: while the friction at contact is high, “IF the reference position is far THEN move the hands quickly forward”. An enhanced dynamic model of the system with high friction at contact for simulation purposes is presented. Simulation results for the manipulation control with the proposed fuzzy controllers are presented to verify the validity of the proposed control algorithm in the achievement of the manipulation motion.

Part orientation with one or two stable equilibria using programmable force fields

Programmable force fields are a representation of a class of devices for distributed, nonprehensile manipulation for applications in parts feeding, sorting, positioning, and assembly. They generate force vector fields in which the parts move until they reach a stable equilibrium pose. Research has yielded open-loop strategies to uniquely position, orient, and sort parts. These strategies typically consist of several fields employed in sequence to achieve a desired final pose. The length of the sequence depends on the complexity of the part. We show that unique part poses can be achieved with just one field. First, we exhibit a single field that positions and orients any part (except certain symmetric parts) into two stable equilibrium poses. Then, we show that for any part there exists a field in which the part reaches a unique stable equilibrium pose (again, except for symmetric parts). Besides giving an optimal upper bound for unique parts positioning and orientation, our work gives further evidence that programmable force fields are a powerful tool for parts manipulation. Our second result also leads to the design of "universal parts feeders", proving an earlier conjecture about their existence. We argue that universal parts feeders are relatively easy to build, and we report on extensive simulation results which indicate that these devices may work very well in practice. We believe that the results in this paper could be the basis for a new generation of efficient, open-loop, parallel parts feeders.