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Performance of a haptic device is evaluated based on the concept of transparency which indicates the match between the impedance transmitted to the user and the target virtual impedance. Stability of a haptic device prevalently has been evaluated based on the passivity criterion. Due to conservativeness of passivity, it appears as an obstacle to im...
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... x hn gives the nominal value of the parameter x, and x hd is the maximum relative uncertainty and || 1. As shown in Fig. 1, feedback connection of robot impedance Zr, and uncertain hand admittance can be represented by an upper linear fractional transform of a generalized control plant PZH, and a 3×3 perturbation matrix ∆. The robust stability of the perturbed closed loop system can be determined by the application of small gain theorem with the [12]. The ...
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... order to evaluate the device transparency, the output impedances of the device in the presence of the three controllers are given in Fig. 10 in which the objective is to emulate the nominal virtual spring. It is clear in this figure that the designed controllers can improve device transparency up to the frequency of 100rad/s which is approximately ten times greater than the maximum transparency of the no-control case. In addition, studying the structured singular value of ...
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... is clear in this figure that the designed controllers can improve device transparency up to the frequency of 100rad/s which is approximately ten times greater than the maximum transparency of the no-control case. In addition, studying the structured singular value of the coupled system of the device impedance and user hand, µ, confirms robust stability of the interaction, as shown in Fig.11. It is possible to study effects of various parameters on the interaction stability. ...
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... the ideal case of transparent Effects of device dynamics are more challenging in high acceleration behavior. Fig 13 displays the high acceleration behavior of the device. When there is no control, loading and unloading curves differ considerably; while, application of the proposed control structure causes the two curves to approach each other and the device transparency to increase. ...
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... there is no control, loading and unloading curves differ considerably; while, application of the proposed control structure causes the two curves to approach each other and the device transparency to increase. Fig.12 and Fig.13 are plotted in the presence of G c1 ; the other two controllers give a similar response. ...
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... there is no control, loading and unloading curves differ considerably; while, application of the proposed control structure causes the two curves to approach each other and the device transparency to increase. Fig.12 and Fig.13 are plotted in the presence of G c1 ; the other two controllers give a similar response. ...
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... a 1% power white noise generator followed by a low pass filter is implemented. This cause the system to experience noises with the frequencies up to 60rad/s or 10Hz approximately. This is consistent with the 20Hz sampling frequency since the highest frequency of the signals in the control system should not exceed half of the sampling frequency. Fig. 14 displays the force transmitted to the user during the process in the presence of three controllers. Effects of the three controllers, especially G 3 , are clear in this ...
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... control command which is sent to the device in the presence of measurement noise and the G c2 controller is plotted in Fig. 15. Comparing this plot with those given in Fig. 12, reveals that the control command sent to the device is slightly bigger than the desired output force, and this is consistent with our main ...
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... control command which is sent to the device in the presence of measurement noise and the G c2 controller is plotted in Fig. 15. Comparing this plot with those given in Fig. 12, reveals that the control command sent to the device is slightly bigger than the desired output force, and this is consistent with our main ...
