13 research outputs found
Overview of microgrippers and design of a micro-manipulation station based on a MMOC microgripper
International audienceThis paper deals with an overview of recent microgrippers. As the end-effectors of micromanipulation systems, microgrippers are crucial point of such systems for their efficiency and their reliability. The performances of current microgrippers are presented and offer a stroke extending from 50 m to approximately 2mm and a maximum forces varying from 0,1mN to 600 mN. Then, micromanipulation system based on a piezoelectric microgripper and a SCARA robot is presented
Miniaturgreifer mit opto-thermo-mechanischem Antrieb
Es wird ein Miniaturgreifer vorgestellt, der auf einer geschlossenen, stoffkohärenten Rahmenstruktur basiert, die erstmals von Bögelsack (1995) vorgestellt wurde. Der geschlossene Rahmen besteht aus einem nachgiebigen, elliptischen Ring, der durch Integration eines laminaren Antriebselementes aktiv verformt werden kann. Dabei kann die Änderung des Tangentenwinkels an der dem Rahmen zugrunde liegenden Ellipse zum Antrieb von weiteren Mechanismen genutzt werden. Im vorliegenden Fall wurde der Rahmen mit zwei Fingern versehen, die bei Verformung des Rahmens eine Greifbewegung ausführen
Surgical Applications of Compliant Mechanisms:A Review
Current surgical devices are mostly rigid and are made of stiff materials, even though their predominant use is on soft and wet tissues. With the emergence of compliant mechanisms (CMs), surgical tools can be designed to be flexible and made using soft materials. CMs offer many advantages such as monolithic fabrication, high precision, no wear, no friction, and no need for lubrication. It is therefore beneficial to consolidate the developments in this field and point to challenges ahead. With this objective, in this article, we review the application of CMs to surgical interventions. The scope of the review covers five aspects that are important in the development of surgical devices: (i) conceptual design and synthesis, (ii) analysis, (iii) materials, (iv) maim facturing, and (v) actuation. Furthermore, the surgical applications of CMs are assessed by classification into five major groups, namely, (i) grasping and cutting, (ii) reachability and steerability, (iii) transmission, (iv) sensing, and (v) implants and deployable devices. The scope and prospects of surgical devices using CMs are also discussed
Microgripper force feedback integration using piezoresistive cantilever structure
Force feedback is an important feature in most microgripper applications, but it is commonly overlooked. To successfully implement this feature, a cantilever structure has been designed and fabricated to integrate force feedback into a microhand gripper. The piezoresistive properties of doped polysilicon are used to transduce the mechanical stress of an object pressing against the cantilever sensor, resulting in a change in resistance or voltage capable of being monitored with external hardware. The force sensing structure was designed to have a fabrication process compatible with that of the microhand, allowing for their eventual integration. This fabrication process uses both bulk and surface micromachining techniques to create the cantilever structure, a balloon actuator (utilized in the microhand), and the interconnect to interact with both the electrical sensors and the pneumatic actuators. The prototype fabrication successfully defined the majority of the MEMS device with the exception of the final step. The release of the cantilever failed due to underetching of the entire device rather than just the cantilever, which was desired. Recommendations to solve this problem and improve the fabrication process are presented
Development of novel micropneumatic grippers for biomanipulation
Microbjects with dimensions from 1 μm to 1 mm have been developed
recently for different aspects and purposes. Consequently, the development of
handling and manipulation tools to fulfil this need is urgently required.
Micromanipulation techniques could be generally categorized according to
their actuation method such as electrostatic, thermal, shape memory alloy,
piezoelectric, magnetic, and fluidic actuation. Each of which has its advantage
and disadvantage. The fluidic actuation has been overlooked in MEMS despite
its satisfactory output in the micro-scale.
This thesis presents different families of pneumatically driven, low cost,
compatible with biological environment, scalable, and controllable
microgrippers. The first family demonstrated a polymeric microgripper that
was laser cut and actuated pneumatically. It was tested to manipulate microparticles
down to 200 microns. To overcome the assembly challenges that
arise in this family, the second family was proposed.
The second family was a micro-cantilever based microgripper, where the
device was assembled layer by layer to form a 3D structure. The microcantilevers
were fabricated using photo-etching technique, and demonstrated
the applicability to manipulate micro-particles down to 200 microns using
automated pick-and-place procedure. In addition, this family was used as a
tactile-detector as well. Due to the angular gripping scheme followed by the
above mentioned families, gripping smaller objects becomes a challenging
task. A third family following a parallel gripping scheme was proposed
allowing the gripping of smaller objects to be visible. It comprises a compliant
structure microgripper actuated pneumatically and fabricated using picosecond
laser technology, and demonstrated the capability of gripping microobject
as small as 100 μm microbeads. An FEA modelling was employed to
validate the experimental and analytical results, and excellent matching was
achieved
A novel approach to micro-telemanipulation with soft slave robots: integrated design of a non-overshooting series elastic actuator
Micro mechanical devices are becoming ubiquitous as they find increas-
ing uses in applications such as micro-fabrication, micro-surgery and micro-
probing. Use of micro-electromechanical systems not only offer compactness
and precision, but also increases the efficiency of processes. Whenever me-
chanical devices are used to interact with the environment, accurate control
of the forces arising at the interaction surfaces arise as an important chal-
lenge.
In this work, we propose using a series elastic actuation (SEA) for micro-
manipulation. Since an SEA is an integrated mechatronic device, the me-
chanical design and controller synthesis are handled in parallel to achieve the
best overall performance.
The mechanical design of the μSEA is handled in two steps: type selection
and dimensional synthesis. In the type selection step, a compliant, half
pantograph mechanism is chosen as the underlying kinematic structure of the
coupling element. For optimal dimensioning, the bandwidth of the system,
the disturbance response and the force resolution are considered to achieve
good control performance with high reliability. These objectives are achieved
by optimizing the manipulability and the stiffness of the mechanism along
with a robustness constraint.
In parallel with the mechanical design, a force controller is synthesized.
The controller has a cascaded structure: an inner loop for position control
and an outer loop for force control. Since excess force application can be detrimental during manipulation of fragile objects; the position controller of
the inner loop is designed to be a non-overshooting controller which guar-
antees the force response of the system always stay lower than the reference
value.
This self-standing μSEA system is embedded into a 3-channel scaled tele-
operation architecture so that an operator can perform micro-telemanipulation.
Constant scaling between the master and the slave is implemented and the
teleoperator controllers preserve the non-overshooting nature of the μSEA.
Finally, the designed μSEA based micro-telemanipulation system is im-
plemented and characterized
Creative design and modelling of large-range translation compliant parallel manipulators
Compliant parallel mechanisms/manipulators (CPMs) are parallel manipulators that
transmit motion/load by deformation of their compliant members. Due to their merits
such as the eliminated backlash and friction, no need for lubrication, reduced wear and
noise, and monolithic configuration, they have been used in many emerging
applications as scanning tables, bio-cell injectors, nano-positioners, and etc.
How to design large-range CPMs is still a challenging issue. To meet the needs for
large-range translational CPMs for high-precision motion stages, this thesis focuses on
the systematic conceptual design and modelling of large-range translational CPMs with
distributed-compliance.
Firstly, several compliant parallel modules with distributed-compliance, such as
spatial multi-beam modules, are identified as building blocks of translational CPMs. A
normalized, nonlinear and analytical model is then derived for the spatial multi-beam
modules to address the non-linearity of load-equilibrium equations. Secondly, a new
design methodology for translational CPMs is presented. The main characteristic of the
proposed design approach is not only to replace kinematic joints as in the literature, but
also to replace kinematic chains with appropriate multiple degrees-of-freedom (DOF)
compliant parallel modules. Thirdly, novel large-range translational CPMs are
constructed using the proposed design methodology and identified compliant parallel
modules. The proposed novel CPMs include, for example, a 1-DOF compliant parallel
gripper with auto-adaptive grasping function, a stiffness-enhanced XY CPM with a
spatial compliant leg, and an improved modular XYZ CPM using identical spatial
double four-beam modules. Especially, the proposed XY CPM and XYZ CPM can
achieve a 10mm’s motion range along each axis in the case studies. Finally,
kinematostatic modelling of the proposed translational CPMs is presented to enable
rapid performance characteristic analysis. The proposed analytical models are also
compared with finite element analysis