Development of Multi Joint Gripper That Achieves Transition From Pinching to Envelope Grasping With Simple Control

2017 ◽  
Author(s):  
Takumi Tamamoto ◽  
Soichiro Nomura ◽  
Keita Takeuchi ◽  
Koichi Koganezawa
Keyword(s):  
Sensory Feedback ◽  
Variable Stiffness ◽  
Gear System ◽  
The Other ◽  
Differential Gear

This study proposes a Multi Joint Gripper (MJG) that achieves envelope grasping for unknown shape objects with simple control. In our previous study we have developed the MJG having a number of multi joint fingers. Each finger has back drivability with Variable Stiffness Mechanism (VSM) for adjusting the stiffness of joints. The MJG succeeded envelope grasping of various shape objects with no sensory feedback. We have also showed the MJG is able to handle objects by pinching with the finger tips and to shift into an envelope grasping. However, in some tasks requiring transition from pinching to envelope grasping, it occasionally failed because of difference of mode setting between pinching and grasping. In this paper, we discuss the pinching motion and the transition from pinching to envelope grasping. The finger mechanism we have proposed is mainly composed of a serially connected Differential Gear System (DGS), and it is controlled by only two actuators. One for driving all of the joints simultaneously and the other for VSM of every joints all together. We propose a novel mechanism for transition from pinching to envelope grasping , which requires no change of mechanical mode setting of the DGS. The experiments revealed that the MJG successfully achieves transition from pinching to envelope grasping with very simple control.

Development of Gripper to Achieve Envelope Grasping with Underactuated Mechanism Using Differential Gear

2018 ◽  
Vol 30 (6) ◽  
pp. 855-862 ◽  
Author(s):  
Takumi Tamamoto ◽  
Keita Takeuchi ◽  
Koichi Koganezawa ◽  
◽  
Keyword(s):  
Sensory Feedback ◽  
Joint Stiffness ◽  
The Other ◽  
Precise Position ◽  
Underactuated Mechanism ◽  
Drive Mechanism ◽  
Differential Gear ◽  
Gear Systems

In a previous study, we developed a seven-axis multi-joint gripper (MJG) with a mechanism for varying the joint stiffness and showed that it was capable of dexterous grasping. In this research, we expand this design by introducing a hand with several multi-jointed fingers. The mechanism of grasping with this hand involves the use of serially connected differential gear systems (DGSs). The DGSs are controlled by only two actuators: one for driving the joints simultaneously and the other for adjusting the stiffness of all of the joints. The hand is shown to successfully grasp and envelope objects of some shapes without sensory feedback and handle objects by pinching them with the finger tips and subsequently transitioning to an envelope grasp. The mechanism that significantly contributes to this result is the tip roller attached to the fingertip. It is incorporated into the joint drive mechanism using a DGS. These functionalities are considerably advantageous in scenarios where information about the objects to be grasped, such as the shape and precise position, cannot be obtained.

scholarly journals Variable Stiffness Mechanism for the Reduction of Cutting Forces in Robotic Deburring

2021 ◽  
Vol 11 (6) ◽  
pp. 2883
Author(s):  
Matteo Bottin ◽  
Silvio Cocuzza ◽  
Matteo Massaro
Keyword(s):  
Conceptual Design ◽  
Cutting Forces ◽  
Variable Stiffness ◽  
Optimization Method ◽  
The Other ◽  
Design Parameters ◽  
Test Cases ◽  
Dynamic Simulations ◽  
Main Design ◽  
The One

One of the main issues related to robotic deburring is that the tool can get damaged or stopped when the burr thickness exceeds a certain threshold. The aim of this work is to devise a mechanism that can reduce cutting forces automatically, in the event that the burr is too high, and is able to return to the baseline configuration when the burr thickness is acceptable again. On the one hand, in normal cutting conditions, the mechanism should have high stiffness to ensure high cutting precision. On the other hand, when the burr is too high the mechanism should exploit its compliance to reduce the cutting forces and, as a consequence, a second cutting cycle will be necessary to completely remove the burr. After the conceptual design of the mechanism and the specification of the desired stiffness curve, the main design parameters of the system are derived thanks to an optimization method. The effectiveness of the proposed mechanism is verified by means of dynamic simulations using selected test cases. A reduction up to 60% of the cutting forces is obtained, considering a steel burr up to 6 mm high.

scholarly journals Multi Joint Gripper with Differential Gear System

2015 ◽  
Vol 33 (9) ◽  
pp. 689-695
Author(s):  
Takumi Tamamoto ◽  
Kazuhiro Sayama ◽  
Koichi Koganezawa
Keyword(s):  
Gear System ◽  
Differential Gear

scholarly journals Dynamic Characteristics Analysis of the Coupled Lateral-Torsional Vibration with Spur Gear System

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Shihua Zhou ◽  
Zhaohui Ren ◽  
Guiqiu Song ◽  
Bangchun Wen
Keyword(s):  
Dynamic Characteristics ◽  
Torsional Vibration ◽  
Variable Stiffness ◽  
Transmission Error ◽  
Spur Gear ◽  
Rotational Frequency ◽  
Gear System ◽  
Bearing Clearance ◽  
Rotor Bearing ◽  
Bearing System

A sixteen-degree-of-freedom (16-DOF) lumped parameter dynamic model taking into account the gravity, eccentricity, bearing clearance, transmission error, and coupled lateral-torsional vibration is established. Based on the dynamical equation, the dynamic behaviors of the spur gear rotor bearing system are investigated by using Runge-Kutta method. The research focuses on the effect of rotational speed, eccentricity, and bearing clearance and nonlinear response of the coupled multibody dynamics is presented by vibration waveform, spectrum, and 3D frequency spectrum. The results show that the rotational frequency of the driven gear appears in the driving gear, and the dynamic characteristics of gears have obvious differences due to the effects of the gear assembly and the coupled lateral-torsional vibration. The bearing has its own resonance frequency, and the effect of the variable stiffness frequency of the bearings should be avoided during the system design. The results presented in this paper show an analysis of the coupled lateral-torsional vibration of the spur gear system. The study may contribute to a further understanding of the dynamic characteristics of such a spur gear rotor bearing system.

scholarly journals Speaking with an alien voice: Flexible sense of agency during vocal production

2020 ◽  
Author(s):  
Matthias K. Franken ◽  
Robert Hartsuiker ◽  
Petter Johansson ◽  
Lars Hall ◽  
Andreas Lind
Keyword(s):  
Auditory Feedback ◽  
Sensory Feedback ◽  
The Other ◽  
Sense Of Agency ◽  
Comparison Process ◽  
Vocal Production ◽  
Internal Representations ◽  
Normal Voice ◽  
Comparator Model ◽  
Joint Contribution

Speakers monitor auditory feedback during speech production in order to correct for speech errors. The comparator model proposes that this process is supported by comparing sensory feedback to internal predictions of the sensory consequences of articulation. Additionally, this comparison process is proposed to support the sense of agency over vocal output. The current study tests this hypothesis by asking whether mismatching auditory feedback leads to a decrease in the sense of agency as measured by speakers’ responses to pitch-shifted feedback. Participants vocalized while auditory feedback was unexpectedly and briefly pitch-shifted. In addition, in one block, the entire vocalization’s pitch was baseline-shifted (‘alien voice’), while it was not in the other block (‘normal voice’). Participants compensated for the pitch shifts even in the alien voice condition, suggesting that agency was flexible. This is problematic for the classic comparator model, where a mismatching feedback would lead to a loss of agency. Alternative models are discussed in light of these findings, including an adapted comparator model and the inferential account, which suggests that agency is inferred from the joint contribution of several multisensory sources of evidence. Together, these findings suggest that internal representations of one’s own voice are more flexible than often assumed.

The Tritonia Swim Central Pattern Generator

2017 ◽  
pp. 561-568
Author(s):  
Paul S. Katz
Keyword(s):  
Central Pattern Generator ◽  
Sensory Feedback ◽  
Pattern Generator ◽  
Emergent Property ◽  
The Other ◽  
Entire Body ◽  
Neural Basis ◽  
Sea Slug ◽  
Tritonia Diomedea ◽  
State Dependent

Tritonia diomedea is a sea slug that escapes from predatory starfish by rhythmically flexing its entire body in the dorsal and ventral directions. This escape swim behavior is produced by a central pattern generator (CPG), without needing sensory feedback. There are several features of the neural basis for this response that make it of particular interest for neuroscientists. One is that the CPG is a network oscillator; bursting arises as an emergent property of the neurons and their connectivity. Another interesting feature is that the CPG contains state-dependent, intrinsic neuromodulation: one of the CPG neurons uses the neurotransmitter serotonin (5-HT) to modulate the strength of synapses made by the other CPG neurons under certain conditions. This CPG seems to have evolved from a nonoscillatory network. Finally, there are novel mechanisms for plasticity during learning and in response to injury.

An Innovative Polymeric Material for Microhandling

2008 ◽  
Author(s):  
Claudia Pagano ◽  
Irene Fassi
Keyword(s):  
Crack Detection ◽  
Rf Mems ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Variable Stiffness ◽  
Chemical Reactor ◽  
Great Difficulty ◽  
The Other ◽  
New Materials ◽  
Distributed Sensors

The rationales for the use of microsystems are numerous, including the reduction of consumables (less chemicals in Lab-on-a-Chip), a faster response time (airbag sensors), the enhanced portability (RF-MEMS), the higher resolution (Inkjet printer head), and the higher efficiency (micro-chemical reactor); moreover their application sectors are numerous. For this reason, during the past decades many improvements have been done concerning the design and manufacturing of microsystems and several products have been fabricated for a great variety of applications in the traditional fields, including the medical and biomedical sectors (e.g.: pacemakers, analysis equipments, microtweezers for minimally invasive surgery, micro drug delivery systems), automotive (sensors for safety in cars e.g. electrostatic field sensors for controlling airbags), aeronautics and aerospace (lightweight distributed sensors for micro crack detection), IT (ink jet printers, reading caps for hard disk, micropumps for microprocessor cooling) and telecommunication (e.g. micro optical switches) as well as in more innovative areas, such as household appliances, entertainment and sport equipment (noise canceller ear plugs, variable stiffness tennis racket, skis equipped with piezoelectric active dampers). Nevertheless microproducts have still great difficulty in penetrating the market, mainly due to the limits of the fabrication processes. Indeed, the two main approaches, monolithic and hybrid, show both many issues to overcome. On one side, the monolithic approach has the consolidate expertise of lithographic processes for the manufacturing of electronic devices on one hand, but on the other hand it has the difficulty in producing three dimensional microdevices with good mechanical properties. On the other side, the hybrid approach is suitable for the fabrication of three dimensional microscopic structures but often fails in assembling processes (12). In order to overcome these issues, new materials have often been studied at microscale to extend the manipulation principles of macroproducts to microsystems (e.g. SMA microgripper (1)), but the techniques imported from the assembly of macro components are, usually, not adaptable for microcomponents, which are subject to very strong superficial forces (3). Therefore new techniques for the manipulation of microcomponents, based on innovative principles, have been conceived and have to be further developed. In this paper the use of new materials in combination with a new handling principle has been proposed and the preliminary results concerning the study of the electrostrictive behavior of a dielectric polymeric smart material, which is promising for the assembly of microcomponents, has been presented.

Sound Discrimination Ability of Children with Misarticulation of the /R/ Sound

1973 ◽  
Vol 37 (2) ◽  
pp. 415-420 ◽  
Author(s):  
Virginia I. Wolfe ◽  
Ruth Beckey Irwin
Keyword(s):  
Sensory Feedback ◽  
Sound Production ◽  
External Source ◽  
The Other ◽  
Self Monitoring ◽  
Discrimination Ability ◽  
Monitoring Task ◽  
Sound Discrimination

The ability of 40 children with the consistent misarticulation of the /r/ sound to perceive their error production was evaluated in two tasks of sound discrimination, one, an interoceptive or self-monitoring task in which the child compared his own live-voice sound with that of another speaker; the other, an exteroceptive task in which the child compared both his own sound and that of another speaker, recorded and played back from an external source. Results indicated that the error sound, in contrast to standard sound production, was discriminated more accurately in the exteroceptive than in the interoceptive task. The role of sensory feedback in sound discrimination is discussed along with implications for therapy for misarticulation.

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