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The present paper considers a position and force control method for robot manipulators under holonomic constraints. The constraint surface type is assumed to be known, whereas the parameters of the surface are not known. The parameters of the constraint surface are estimated using the least squares method, and the incorrect target position is modified optimally to be on the true constraint surface...
This paper presents an approach of force control with hydraulic cylinders based on the modification of hydraulic compliance. The force control is one of the most studied topics in hydraulic control systems and previous researches showed that the inclusion of flexible components, such as a spring, between the actuator and the external environment results very useful to obtain a stable force control...
The four hydraulic cylinders pressing equipment is commonly used in superplastic forming equipment and other similar applications. But it hardly to arrange the reaction force in the geometry center of four cylinder which makes the depress equipment unbalance and very harmful for these equipment. In this paper the coupling between four cylinders is considered and the linear model of four-cylinders...
This paper presented a variable structure controller for the nonlinear system, the state information including position, velocity, and acceleration is selected as cascade function, and the stability and robustness are enhanced by making use of exponential convergence. Through classifying factors related to nonlinearity, the Lyapunov function is constructed, and the adaptive control law is developed...
The joint drive of quadruped robot, the highly integrated valve-controlled cylinder (HIVC), whose control performance could effect on the whole machine of the robot directly. In this paper, based on the structure principles of flow servo valve and pressure-flow servo valve, the mathematical models of above two kinds of servo valve are established to analyze their dynamical performance respectively...
Most position/force control schemes assume that the contact surface is exactly known. In the presence of constraint uncertainties these controllers cannot ensure convergence to zero of position and force errors. In this work, an adaptive scheme is proposed for robot manipulators that perform interaction tasks with a rigid surface. The proposed algorithm takes into account uncertainties in robot and...
In this paper a practical method for robust control of an inverted pendulum driven by a linear pneumatic actuator is presented. The whole system mathematical model is derived, verified and utilized in the paper to guide the initial design of the robust control strategy. The control strategy consists of an inner loop controlling the force acting on the piston by means of a PI controller; and the position...
The aim of this paper is to develop a system where forces at the wheels of a ground vehicle are controlled to guide the vehicle along a planned path. The 7-order Bézier curves are applied to path planning and online path tracking, and used to obtain profiles of velocities and accelerations for the guidance of a 4WS4WD vehicle. The dynamic model used for force control is developed for the determination...
Power factor in mechanical system is a new concept to express characteristic in mechanical system. It defines dynamic behavior of the impedance characteristic in the motion. However, conventional derivation method requires short-time Fourier transformation in order to consider random input in mechanical system as a combination of sinusoidal waves. This paper proposes a novel method to obtain power...
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...
The capability of applying a weak force with expected accuracy is an important motor skill in surgical operations. Acquiring such a skill is challenging for novices. In this paper, we studied how the accuracy of the force control could be enhanced through repetitive training. Twelve participants were divided into two groups. They were trained to apply a target force of 0.25N with ±20% accuracy under...
In this paper we propose a new ultrasound-based visual servoing framework, for the optimization of the positioning of an ultrasound probe manipulated by a robotic arm, in order to improve the quality of the acquired ultrasound images. To this end, we use the recent framework of ultrasound confidence map, which aims at estimating the perpixel quality of the ultrasound signal based on a model of sound...
During human-robot interaction tasks, a human may physically touch a robot and engage in a collaboration phase with exchange of contact forces and/or requiring coordinated motion of a common contact point. Under the premise of keeping the interaction safe, the robot controller should impose a desired motion/force behavior at the contact or explicitly regulate the contact forces. Since intentional...
In this paper we propose a novel hybrid Cartesian force/impedance controller that is equipped with energy tanks to preserve passivity. Our approach overcomes the problems of (hybrid) force control, impedance control, and set-point based indirect force control. It allows accurate force tracking, full compliant impedance behavior, and safe contact resemblance simultaneously by introducing a controller...
A new predictive control technique has been proposed in this article. The proposed strategy is based on the control matrix formulation combined with a tuning technique using model regression. Poor dynamics and high nonlinearities are parts of the difficulties in the control of pneumatic actuator functions, which make the proposed matrix an attractive solution. The proposed regression technique expression...
This paper discusses a new control approach for robotic-assisted tele-echography where contact dynamics are driven by a 3D time-of-flight camera and a force sensor. Based on 3D camera and force data, contact stiffness is anticipated, allowing adaptation before contact. This approach enables to slow down robot dynamics before contact which is adequate for tele-echographic tasks. Additionally, free...
We propose an hierarchical control framework for multiple cooperative quadrotor-manipulator systems, which allows us to endow the common grasped object with a user-specified desired behavior (e.g., trajectory tracking, compliant interaction, etc.). To achieve this, our control framework consists of the following hierarchical layers: 1) object desired behavior design; 2) optimal cooperative force distribution;...
Switched-reluctance technology is appealing to the automotive industry due to its cost efficiency. Conventional research focuses on the two main issues torque ripple and acoustic noise. However, control schemes usually only address one of these two issues at a time. This paper unifies the approaches of direct instantaneous torque control and direct instantaneous force control to simultaneously tackle...
In this paper, the application of an impedance control scheme to drive a robot with a desired force profile in the presence of non-rigid environments is considered. Fine force control obtained with the usual impedance based control schemes reveal some difficulties especially for non-rigid environments. Moreover, robot dynamic model and environmental uncertainties, can seriously affect the force tracking...
Currently available upper-limb, myoelectric prostheses usually accomplish gesture differentiation by analyzing myoelectric signals from multiple pairs of surface electrodes distributed over the user’s upper body. Another common control method is to use a single pair of surface electrodes but to enlist an application on a mobile device for specific gesture and grip settings. Both of these approaches...
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