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In the labor-intensive fields, lifting a heavy object up and down is regarded as a frequently performed motion which imposes a physical strain on workers. Power assist systems are expected to address such a problem. However, conventional systems in the related studies have the disadvantage of either the effort for wearing or specified operation manner, which may prevent them from being introduced...
Control approaches for nonholonomic systems have utilized canonical forms. A nonholonomic double integrator model is the one of canonical forms for nonholonomic systems. Outputs of the controller based on the nonholonomic double integrator model are velocity commands for the kinematic model of a nonholonomic system. In this paper, we consider an extended nonholonomic double integrator model, in which...
This paper presents force control systems of a new 6-DOF haptic interface for a 6-DOF serial robot. The haptic interface was designed to operate with three translations and three rotations. First open loop force control is implemented to demonstrate the feed forward static force control based on Jacobian matrix. The error of open loop control can be reduced by a PD controller. However this controller...
Prediction of contact forces is a central issue in robotic grasping analysis and the indetermination of the contact force is one of the most important characteristic for the object-hand system. In this paper, we provide a unified framework to determine the contact force in robotic grasping. First, a nonlinear mapping, based on the Hertz contact theory, was used to build the force-deformation relationship...
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....
This paper presents a design frame of a leg exoskeleton. The performance of an exoskeleton was analyzed by studying a model of a linear coupled 1-DOF human-exoskeleton system. The results showed that a low-impedance, anthropomorphic and well attached mechanical structure is benefit for the control of exoskeleton, and a direct force feedback control could also be implemented to further reduce the impedance...
The controller design is one of the major difficulties in realizing robot-aided rehabilitation program. The purpose of our study is to develop an adaptive impedance force control strategy based on dynamic recurrent fuzzy neural network to maintain the stability of the rehabilitation robot system in the case when the patient's physical condition makes a change. An on-line identification method was...
This paper presents a synchronization scheme of bilateral teleoperation systems with time delay using genetic algorithms. In general, bilateral teleoperation systems have two main goals: stability and transparency. The system can be destabilized by time delay in the communication channel between the master and the slave. Also, transparency can be degraded by time delay. However, it is not easy to...
In this paper, the exoskeleton robot is first briefly introduced, the mathematical model for the upper limb exoskeleton robot and the force and position double-closed-loop control system are discussed. Then the authors discuss the type design of all sectors for the control system, and the various components of the system are given. Lastly, through the use of Matlab's Simulink software, the simulation...
Cable-driven spherical joint is a 3-DOF closed-loop mechanism which transmits motion and force of the driver on the base to the moving platform via cables. It combines the merits of cable-driven and parallel mechanism. This paper introduces a 4-cable-driven parallel structure with 3-DOF and uses a specific methodology to optimize structural parameters of the spherical joint. Based on the analysis...
Impedance control is a common interaction control strategy used in rehabilitation robots. A joint force controller has been developed for a redundantly actuated parallel robot to facilitate force based impedance control. The proposed controller utilizes only position/orientation dependent information and therefore does not require accurate dynamic modeling and measurement of velocity quantities. The...
This paper deals with impedance H∞ control problem of constrained manipulators based on neural network techniques. With this approach, it is guaranteed that the relationship between the force and position errors converges to a given dynamic behavior. The neural networks proposed in this paper adapt only the uncertain dynamics of the robotic manipulator, they actuate as complement of the nominal model...
As computer technology advances and facilitates an increased amount of autonomous sensing and control, the interface between the human and autonomous computer systems becomes increasingly important. This applies in particular in the realm of service robotics where robots with increasing levels of autonomy are constantly interacting with human users and where it is paramount to have an efficient way...
In this paper, a central controller for position/force hybrid control over network is proposed. In the proposed method, the central controller receives position and force information from each plant. Then, the central controller generates acceleration references for each plant by using a hybrid controller and a dead time compensator. As an application, bilateral control with communication delay is...
This paper proposes a method for composition of a task hierarchy as an example of oblique coordinate control. As a primary task, position limitation is implemented and bilateral control is realized secondary. This hierarchy is simply given by a multiple of coordinate transform matrices and the problem can be regarded as position-force hybrid controller in oblique coordinate. Thus, the interference...
In this paper, the objective is to analyze a robot system with consideration the different levels of wire rope tension for human-robot applications. In the controller design, dual disturbance observers with respect to two operation modes, namely the common mode and the differential mode are designed and applied for controlling wire rope tension and interaction force of human. The variable wire rope...
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...
A new type of horizontal lower limbs rehabilitation robot based on parallel mechanism is developed according to the motion law of lower limbs and rehabilitation medicine theory, which is helpful for the disabled patients in lower limbs. It can help patients to do rehabilitation training of hips, knees and ankles. In order to ensure safety and comfort of affected limb in the course of training, the...
The use of robots in assistive roles will be an increasingly significant application for robotics. Assistive robots need to physically interact with humans in a safe manner. We propose the use of inflatable robot links as structural members instead of traditional rigid links. We believe such links would allow the development of inherently safe robots. For these robots to be useful in tasks such as...
This paper presents a predictive force control approach to compensate for the physiological motion induced by both respiratory and heart beating motions during cardiac surgery. It focuses on the design and implementation of the control algorithm in the context of robotized minimally invasive surgery. The controller is based on a linear predictive control loop using the force information applied on...
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