scholarly journals Interacting With Grasped Objects in Expanded Haptic Workspaces Using the Bubble Technique

2015 ◽  
Vol 15 (4) ◽  
Author(s):  
Ryan A. Pavlik ◽  
Judy M. Vance
Keyword(s):  
Virtual Environments ◽  
Collision Detection ◽  
Rate Control ◽  
Force Feedback ◽  
Position Control ◽  
Restoring Force ◽  
End Effector ◽  
Base Position ◽  
Bubble Interaction ◽  
Control Devices

Haptic force-feedback can provide useful cues to users of virtual environments. Body-based haptic devices are portable but the more commonly used ground-based devices have workspaces that are limited by their physical grounding to a single base position and their operation as purely position-control devices. The “bubble technique” has recently been presented as one method of expanding a user's haptic workspace. The bubble technique is a hybrid position-rate control system in which a volume, or “bubble,” is defined entirely within the physical workspace of the haptic device. When the device's end effector is within this bubble, interaction is through position control. When the end effector moves outside this volume, an elastic restoring force is rendered, and a rate is applied that moves the virtual accessible workspace. Publications have described the use of the bubble technique for point-based touching tasks. However, when this technique is applied to simulations where the user is grasping virtual objects with part-to-part collision detection, unforeseen interaction problems surface. Methods of addressing these challenges are introduced, along with discussion of their implementation and an informal investigation.

Expanding Haptic Workspace for Coupled-Object Manipulation

2011 ◽  
Author(s):  
Ryan A. Pavlik ◽  
Judy M. Vance
Keyword(s):  
Virtual Environments ◽  
Collision Detection ◽  
Rate Control ◽  
Force Feedback ◽  
Position Control ◽  
Object Manipulation ◽  
Restoring Force ◽  
End Effector ◽  
Control Scheme ◽  
Bubble Interaction

Haptic force-feedback offers a valuable cue in exploration and manipulation of virtual environments. However, grounding of many commercial kinesthetic haptic devices limits the workspace accessible using a purely position-control scheme. The bubble technique has been recently presented as a method for expanding the user’s haptic workspace. The bubble technique is a hybrid position-rate control system in which a volume, or “bubble,” is defined entirely within the physical workspace of the haptic device. When the device’s end effector is within this bubble, interaction is through position control. When exiting this volume, an elastic restoring force is rendered, and a rate is applied that moves the virtual accessible workspace. Existing work on the bubble technique focuses on point-based touching tasks. When the bubble technique is applied to simulations where the user is grasping virtual objects with part-part collision detection, unforeseen interaction problems surface. This paper discusses three details of the user experience of coupled-object manipulation with the bubble technique. A few preliminary methods of addressing these interaction challenges are introduced.

Position/Rate Haptic Control of a Hydraulic Forklift

2003 ◽  
Author(s):  
Matthew E. Konz ◽  
Wayne J. Book
Keyword(s):  
Rate Control ◽  
Position Control ◽  
Small Region ◽  
End Effector ◽  
Moving Vehicle ◽  
Forklift Truck ◽  
Holonomic Robot ◽  
Haptic Control ◽  
Unconstrained Motion ◽  
Master Device

This paper discusses a haptic control strategy that can switch between position and rate control on the fly. When manipulating a remote device through teleoperation it is often desirable to complete tasks in position mode. This is because the slave is mimicking the motion of the master device (i.e. the human operator). Pure position control breaks down if the slave is a non holonomic device such as a forklift truck, earth moving vehicle or a skid-steer loader and the master has a holonomic robot with a finite workspace. In order to drive around, the forward motion must be controlled in rate mode when the device is move over long distances. Horizontal motion of the vehicle is also used to manipulate the end effector. Since tasks done by end effector are often done in a small region it is desirable to be able to switch into position mode in order to complete tasks with the end effector. Experimental results are presented using a PHANTOM as the haptic display and a Hydraulically Actuate Lifter (HAL) as a remote manipulator. These results show how a position/rate controller would behave in unconstrained motion, in the presence of virtual constraints and while picking up a load with the end effector.

scholarly journals Force-Free Control for Direct Teaching of a Surgical Assistant Robot End Effector with Wire-Driven Bidirectional Telescopic Mechanism

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3498
Author(s):  
Youqiang Zhang ◽  
Cheol-Su Jeong ◽  
Minhyo Kim ◽  
Sangrok Jin
Keyword(s):  
Control Algorithm ◽  
Position Control ◽  
Friction Model ◽  
Surgical Instruments ◽  
Control Input ◽  
End Effector ◽  
Motor Current ◽  
Direct Teaching ◽  
End Effectors ◽  
Teaching Operation

This paper shows the design and modeling of an end effector with a bidirectional telescopic mechanism to allow a surgical assistant robot to hold and handle surgical instruments. It also presents a force-free control algorithm for the direct teaching of end effectors. The bidirectional telescopic mechanism can actively transmit force both upwards and downwards by staggering the wires on both sides. In order to estimate and control torque via motor current without a force/torque sensor, the gravity model and friction model of the device are derived through repeated experiments. The LuGre model is applied to the friction model, and the static and dynamic parameters are obtained using a curve fitting function and a genetic algorithm. Direct teaching control is designed using a force-free control algorithm that compensates for the estimated torque from the motor current for gravity and friction, and then converts it into a position control input. Direct teaching operation sensitivity is verified through hand-guiding experiments.

scholarly journals Magnetic Driven Two-Finger Micro-Hand with Soft Magnetic End-Effector for Force-Controlled Stable Manipulation in Microscale

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 410
Author(s):  
Dan Liu ◽  
Xiaoming Liu ◽  
Pengyun Li ◽  
Xiaoqing Tang ◽  
Masaru Kojima ◽  
...  
Keyword(s):  
Magnetic Force ◽  
Force Feedback ◽  
Soft Magnetic ◽  
End Effector ◽  
Force Microscopy ◽  
System A ◽  
Atomic Force ◽  
Afm Probe ◽  
End Effectors ◽  
Fixed End

In recent years, micromanipulators have provided the ability to interact with micro-objects in industrial and biomedical fields. However, traditional manipulators still encounter challenges in gaining the force feedback at the micro-scale. In this paper, we present a micronewton force-controlled two-finger microhand with a soft magnetic end-effector for stable grasping. In this system, a homemade electromagnet was used as the driving device to execute micro-objects manipulation. There were two soft end-effectors with diameters of 300 μm. One was a fixed end-effector that was only made of hydrogel, and the other one was a magnetic end-effector that contained a uniform mixture of polydimethylsiloxane (PDMS) and paramagnetic particles. The magnetic force on the soft magnetic end-effector was calibrated using an atomic force microscopy (AFM) probe. The performance tests demonstrated that the magnetically driven soft microhand had a grasping range of 0–260 μm, which allowed a clamping force with a resolution of 0.48 μN. The stable grasping capability of the magnetically driven soft microhand was validated by grasping different sized microbeads, transport under different velocities, and assembly of microbeads. The proposed system enables force-controlled manipulation, and we believe it has great potential in biological and industrial micromanipulation.

scholarly journals A Magnetorheological Fluids-Based Robot-Assisted Catheter/Guidewire Surgery System for Endovascular Catheterization

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 640
Author(s):  
Linshuai Zhang ◽  
Shuoxin Gu ◽  
Shuxiang Guo ◽  
Takashi Tamiya
Keyword(s):  
Collision Detection ◽  
Endovascular Procedures ◽  
Force Feedback ◽  
Force Measurement ◽  
Occupational Hazards ◽  
Robot Assisted ◽  
X Ray ◽  
Surgical Safety ◽  
Surgical Tool ◽  
Haptic Cues

A teleoperated robotic catheter operating system is a solution to avoid occupational hazards caused by repeated exposure radiation of the surgeon to X-ray during the endovascular procedures. However, inadequate force feedback and collision detection while teleoperating surgical tools elevate the risk of endovascular procedures. Moreover, surgeons cannot control the force of the catheter/guidewire within a proper range, and thus the risk of blood vessel damage will increase. In this paper, a magnetorheological fluid (MR)-based robot-assisted catheter/guidewire surgery system has been developed, which uses the surgeon’s natural manipulation skills acquired through experience and uses haptic cues to generate collision detection to ensure surgical safety. We present tests for the performance evaluation regarding the teleoperation, the force measurement, and the collision detection with haptic cues. Results show that the system can track the desired position of the surgical tool and detect the relevant force event at the catheter. In addition, this method can more readily enable surgeons to distinguish whether the proximal force exceeds or meets the safety threshold of blood vessels.

scholarly journals Proposal of a Decoupled Structure of Fuzzy-PID Controllers Applied to the Position Control in a Planar CDPR

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 745
Author(s):  
Marco Carpio ◽  
Roque Saltaren ◽  
Julio Viola ◽  
Cristian Calderon ◽  
Juan Guerra
Keyword(s):  
Position Control ◽  
Control Structure ◽  
Parallel Robot ◽  
Pid Controllers ◽  
Fuzzy Pid ◽  
End Effector ◽  
Robot Systems ◽  
Decoupled Control ◽  
The Mathematical Model ◽  
Decoupled Structure

The design of robot systems controlled by cables can be relatively difficult when it is approached from the mathematical model of the mechanism, considering that its approach involves non-linearities associated with different components, such as cables and pulleys. In this work, a simple and practical decoupled control structure proposal that requires practically no mathematical analysis was developed for the position control of a planar cable-driven parallel robot (CDPR). This structure was implemented using non-linear fuzzy PID and classic PID controllers, allowing performance comparisons to be established. For the development of this research, first the structure of the control system was proposed, based on an analysis of the cables involved in the movement of the end-effector (EE) of the robot when they act independently for each axis. Then a tuning of rules was carried out for fuzzy PID controllers, and Ziegler–Nichols tuning was applied to classic PID controllers. Finally, simulations were performed in MATLAB with the Simulink and Simscape tools. The results obtained allowed us to observe the effectiveness of the proposed structure, with noticeably better performance obtained from the fuzzy PID controllers.

scholarly journals Manipulator End-Effector Position Control

2012 ◽  
Vol 48 ◽  
pp. 684-692 ◽  
Author(s):  
Ivan Virgala ◽  
Alexander Gmiterko ◽  
Róbert Surovec ◽  
Martina Vacková ◽  
Erik Prada ◽  
...  
Keyword(s):  
Position Control ◽  
End Effector

Virtual Environments for Motor Fine Skills Rehabilitation with Force Feedback

2017 ◽  
pp. 94-105 ◽  
Author(s):  
Víctor H. Andaluz ◽  
Cartagena Patricio ◽  
Naranjo José ◽  
Agreda José ◽  
López Shirley
Keyword(s):  
Virtual Environments ◽  
Force Feedback
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