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Tactile information is valuable in determining properties of objects that are inaccessible from visual perception. In this work, we present a tactile perception strategy that allows any mobile robot with tactile sensors in its gripper to measure a set of generic tactile features while grasping an object. We propose a hybrid velocity-force controller, that grasps an object safely and reveals at the...
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,...
In this paper, we consider a 3D grasping problem. In previous work, we presented the central-axis approach and proven its capability to analyze multifingered grasps. In the present paper, we extend our study by developing and analyzing modified force-closure algorithms, and giving rigorous theoretical demonstrations. Through numerical simulations, we show that the proposed approach is computationally...
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...
We have previously shown that a hemispherical soft fingertip is in equilibrium when it is in contact with an object. The characteristics of the contact force and flexibility of a soft fingertip are important in stable grasping and manipulation. Hence, using these characteristics soft fingers can manipulate objects dexterously. We previously focused on a pair of 1-DOF fingers with soft fingertips....
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...
In this paper we present a framework for combining force and visual feedback in the task space to deal with humanoid interaction tasks like open doors in a real kitchen environment. We present stereo-vision methods for markerless recognition and estimation of environmetal elements for applying force control strategies for compliant execution using a 6D force-torque sensor mounted in the humanoids's...
In this paper, we propose a new internal model control based controller for sensorless force control. Simplification of the proposed controller is discussed, and stability of the controller is proved theoretically. Two controllers based on internal model control are applied to sensorless grasping control on a myoelectric robotic hand. Effectiveness of the proposed controllers is verified by comparative...
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...
Objective of the overall system is that of understanding (and demonstrating) what are the tasks that a robotic crew assistant must be able to execute, in order to be effective for space exploration missions. One of the most important tasks to be accomplished is the autonomous grasping of objects, which has been achieved through a vision and force-based control strategy. This paper deals with the completion...
Two main problems in the manipulation of objects with robot-hands are the control of the contact force and the planning of approaching motion. In this paper, we report on the three types of MEMS sensors for robots to detect the contact forces, slippage and the distance to the objects to realize dexterous manipulation of objects with robot-hands. As a tactile sensor, we propose standing piezoresistive...
Space debris objects are generally tumbling in orbit, and so capturing and braking them involves complicated dynamical interactions between the object, the so-called ldquoremoverrdquo spacecraft, and its robot arm, with the possibility of strong loading occurring during the procedure. In this paper, the remover and its space debris capture strategy is described which proposes the application of joint...
In this paper, modal transform method for cooperation working is proposed. With this method, the work is simply described by modal mass and arbitral number and location of robots are able to be controlled by conventional hybrid controller. Furthermore, rotation by linear actuators, one of the most important propositions in this research, is considered. Position, angle, force and torque are transformed...
We present a system which includes an underactuated anthropomorphic hand and control algorithms for autonomous grasping of everyday objects. The system comprises a control framework for hybrid force/position control in simulation and reality, a grasp simulator, and an under-actuated robot hand equipped with tactile sensors. We start by presenting the robot hand, the simulation environment and the...
The smaller the robot the easier it is for it to access voids in a collapsed structure. Yet, small size brings a host of problems due to resource constraints. One of the primary constraints on small robots is limited motive power to surmount obstacles and rough terrain. We are developing a small reconfigurable robotic system with various add-on modules to provide bulk motive force adaptable for different...
Two methods of prosthetic hand control are investigated. A typical proportional force control scheme is compared to a force controller with a feedforward inertia stopping derivative term. Eleven human operators use these two controllers with an antagonist electromyogram input. The experimental feedforward force controller is found to help prevent unwanted force overshoot when initially grasping objects.
Hierarchical and wider applications of robots, manipulators, and pick and place machines are facing challenges in industrial environments due to their insufficient intelligence for appropriately recognizing objects for grasping and handling purposes. Since robots do not posses self-consciousness, estimation of adequate grasping force for individual objects by robots or manipulators is another challenge...
This paper presents a grasping/manipulating control method using mode transformation. Discrete Fourier transform (DFT) matrices are utilized as transformation matrices. In grasping/manipulating control systems, decomposition into grasping motion and manipulating motion remains a key problem. By means of the proposed method, the grasping controller and the manipulating controller can be designed independently...
This paper presents a model of multiple robotic mechanisms (compliant mechanical fingers) in contact with an object and a method for controlling the contact forces. In the model, springs and dampers (compliant properties) are connected in parallel between the end-points of the mechanisms and the object. Using this model a centralized contact force controller is proposed. This controller is based on...
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