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Nhiều chương trình CAD hiện nay cho phép tạo ra các mô hình ba chiều để có thể nhìn từ mọi góc độ. Các chương trình CAD mô hình hóa vật thể đặc tiên tiến là một hệ thống thiết kế hiện thực ảo. Những mô hình đặc như vậy có thể được dùng làm cơ sở cho các phân tích phần tử hữu hạn (FEA) và / hoặc tính toán động lực dòng chảy (CFD) của thiết kế. Cho đến ứng dụng gia công với trợ giúp máy tính (CAM), những mô hình này cũng có thể được dùng. | 272 Advances in Haptics see 5 c and 5 d . The time shift between the two data sets is set to 30 Ts . With these values the stiffness presented to the human operator kth Kka behaves sufficiently smooth and accommodates sufficiently fast to changes in the environment stiffness for a e 1 3 . The scaling factor K has to be used to maintain the absolute value of the stiffness presented to the human operator at a similar value as the real environment stiffness. Hereto the nominal environment stiffness has to be known or estimated a priori. 5. Experimental results part I As stated in the introduction controllers of the third concept show better robustness compared to controllers of the first concept. The experiments described in this section compare the Stiffness Reflecting Controller SRC a controller of the third concept to the Direct Force Feedback Controller DFF a controller of the first concept. A number of experiments are performed on the experimental master-slave setup described in Section 3 a comparison of the two controllers subsection 5.1 a comparison of the two controllers when a low-pass filter with cutoff frequency of 3.2 Hz is present subsection 5.2 and a comparison of the two controllers when a 100 ms time delay was introduced on both the control and the communication channel subsection 5.3 . Moreover a last experiment shows the interaction with a nonlinear environment having the material properties of typical cardiovascular tissue subsection 5.4 . 5.1 SRCvs. DFF During this experiment a linear tension spring ke 1100 N m is manipulated. Figure 9 a and 9 b show the experimental data acquired during this manipulation for respectively the DFF and the SRC. For the DFF as mentioned in Section 3.3 the stiffness felt by the operator is the series connection of the environment stiffness ke and the stiffness of the position controller Kp following expression 16 . Linear curve fitting shows that the stiffness presented to the operator is 850 N m. This approximates the
