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An anti-ejection control strategy was proposed for the characteristics of underactuated prosthetic hand grasping process. The reference position can be calculated and the stiffness of objects can be estimated by the feedback signals of force and position. When the driving joint approaches the reference position and the actual grasp force does not reach the desired value, which means that the ejection...
In our research work we designed a robotic gripper for industrial robotic arm which is capable of grasping any rigid as well as delicate objects. Our control system produces an adequate force to grasp any object. In this paper, we designed a gripper mechanism and a controller. Force sensor was fixed at the gripper finger to collect the force values while grasping. We implemented proportional-integral-derivative...
Controlling absolute magnitudes of fingertip force is an important skill in many haptic interactions such as surgical operations and mechanical assemblies. A fundamental question in the force control is how quickly human can output a target force with expected accuracy. In this paper, human's capability to control absolute magnitudes of fingertip force under audio or visual feedback was observed through...
This study investigates how controllability of force is influenced by concurrent vibrotactile feedback that is generated proportionally to the applied force. Three different models to provide tactile feedback are introduced: amplitude and frequency modulation and granular synthesis. Then, an experiment investigating the effect of the feedback models on force control is reported. The tactile feedback...
Robot's blind tracking of an unknown surface with high speed is a critical problem of force control, to avoid damage to breakable objects, such as a bulb. It must deal with a typical action-based intelligence directly from force sensing to action in robot tracking and understanding of unknown external environments. Bio-inspired by human finger tracking, the realization of high-speed tracking relies...
This paper investigates the control algorithm of an exoskeleton for hand rehabilitation, which accomplishes both active and passive rehabilitation training. In the passive mode control the PID control algorithm is executed in the velocity mode of the driver. In the active mode control, control architecture is proposed to deal with in both free space and constraint space. A resistance compensation...
This article presents an intelligent fuzzy rule-based approach for computing optimal set of joints torques, for manipulating a grasped object by a dexterous multi-fingered robotics hand. The intelligent approached followed here, is to let a learning fuzzy system to approximate a nonlinear force formulation for optimal contact forces. This has been achieved via following two major steps: The first...
We have developed a hydraulic McKibben artificial muscle which realizes great force density approximately ten times larger than the other conventional actuators. In this paper, we have applied this muscle to a power robot hand. The hand finger consists of metal links and the muscles. The contraction of the muscles generates the bending motion of the fingers. This hand has large holding capacity and...
We present a novel Weighted Barrier Function (WBF) method of efficiently computing optimal grasping force distributions for multifingered hands. Second-order conic friction constraints are not linearized, as in many previous works. The force distributions are smooth and rapidly computable, and they enable flexibility in selecting between firm, stable grasps or looser, more efficient grasps. Furthermore,...
To fulfil the principle of low-cost and easy operation features, a new control scheme is proposed for the LARM Hand in this paper. The new controller is composed of a high level PC-based control panel and a low level DSP control card and the two parts communicate with each other through RS-232. The PC-based control panel is software with which an operator can input control parameters, and additionally...
The single-motor multiple DOFs under-actuated finger is the focus of robot research. The grasping force of traditional under-actuated hands based on linkages is hard to control. The traditional hands also have many differences from human hands in appearance. Aiming to solve these problems, this paper has presented a novel under-actuated hand based on linkages, which also comprises of slider mechanisms...
Grasping and handling delicate objects with robotic systems could be done by force closure method which needs a sophisticated control capable of providing stable grasping of the object with minimum possible normal force. It is a common practice among researchers to simplify dynamic of system by assumpssions such as permanent contact or incipient slip condition between object and gripper. Although...
Grasping and handling delicate objects with robotic systems could be done by force closure method which needs a sophisticated control capable of providing stable grasping of the object with minimum possible normal force. It is a common practice among researchers to simplify dynamic of system by assumpssions such as permanent contact or incipient slip condition between object and gripper. Although...
Robot hands based on fluidic actuators are a promising technology for humanoid robots due to their compact size and excellent power-weight-ratio. Yet, such actuators are difficult to control due to the inherent nonlinearities of pneumatic systems. In this paper we present a control approach based on a simplified model of the fluidic actuator providing force and position control and further fingertip...
In order to eliminate the drawbacks of conventional force feedback gloves, a new type of master hand has been developed. By utilizing three ??four-bar mechanism joint?? in series and wire coupling mechanism, the master finger transmission ratio is kept exact 1:1.4:1 in the whole movement range and it can make active motions in both extension and flexion direction. Additionally, to assure faster data...
In the force control of multi-functional prosthetic hands, it is important to extract grasp force information besides mode specifications directly from the myoelectric signals. In this paper, a force sensor is adopted to record the hand's enveloping force when the hand is performing several grasp modes, synchronously with 6 channels surface electromyography (EMG) which are extracting from the subject's...
In order to eliminate twisting deformation of the flexible pneumatic finger, the mechanical structure of the pneumatic finger is improved and a rigid chain component is designed for it. The flexible finger automatically adapts well to the irregular shape of grasping object. The change of the pressure value of the compressed air in the flexible finger and the output force of the finger when grasping...
A bidirectional force feedback dataglove actuated by pneumatic artificial muscles is introduced which has simpler exoskeleton structure and exerts bidirectional force only on the fingertips. Moreover, its fewer attachments can reduce the effect of the attachment looseness on the accuracy of position and force control. It meets all needs of virtual reality and the requirement of hand rehabilitation...
This paper presents an anthropomorphic prototype hand prosthesis that is intended for use with a multiple channel myoelectric interface. The hand contains 16 joints, which are differentially driven by a set of five independent actuators. The hand prototype was designed with the minimum number of independent actuators required to provide a set of eight canonical hand postures. This paper describes...
In a previous paper, we developed a robotic finger equipped with optical three-axis tactile sensors, of which the sensing cell can separately detect normal and shearing forces. With appropriate precision, the robotic finger was able to perform three tasks: scanning flat specimens to obtain the friction coefficient, following the contour of objects, and manipulating a parallelepiped case put on a table...
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