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Fig. 7. The diagram of dependence of position + velocity in time (left) and acceleration + velocity in time (right), VMMR is moving on vertical surface in vertical way down (moving out, mass 30 kg).
Fig. 8. The diagram of dependence of position + velocity in time (left) and acceleration + velocity in time (right), VMMR is moving on vertical surface in horizontal way (moving in, mass 70 kg).
Fig. 9. The diagram of dependence of position + velocity in time (left) and acceleration + velocity in time (right), VMMR is moving on vertical surface in vertical way down (moving in, mass 70 kg).
Fig 9. shows the very specific dependence of acceleration in time at the beginning of the movement (see process on 0,12 sec). This type of acceleration curve explains by inclusion in computer control algorithm special delay to activate throttles T1 and T2 when moving in. After signal generates, valve V is switching to the right position and the air can exhaust from the rodless chamber only through the orifice of throttle T3. After delay in 100 ms throttles T1 and T2 are activated too. Results of computer simulation testifies that including of such kind of delay can decrease dynamic loads at the start of the movement more than twice when the direction of movement coincides with gravity.
It is important to note that application of VMMR means the change of the angle of axis of pneumatic cylinders concerning the horizon. That causes changing of forces acting on the object connected with rod.
Results of computer simulation with different orientation of mobile platform concerning the horizon represented in Table 1 for different stages of the movement. is an angle of orientation of platform and pneumatic cylinders. If = 0O – it is a horizontal orientation, if = 90O – vertical orientation, rod upside, if = -90O – vertical orientation, rod downside. In table 1 we can find the speed of piston when it contacts the cap, maximum dynamic load while the braking process and time of the movement when cylinder is moving in and moving out. Structure, parameters of the drive and adjustments of throttles are invariable.
Table 1. Results of computer simulation with using of cylinder diameter 50 mm and various angles of orientation.
90 97 mm/sec; 170 N; 0,92 sec. 31 mm/sec; 371 N; 0,93 sec.
60 68 mm/sec; 173 N; 0,92 sec. 38 mm/sec; 343 N; 0,95 sec.
30 30 mm/sec; 173 N; 0,89 sec. 29 mm/sec; 336 N; 0,97 sec.
0 59 mm/sec; 173 N; 0,88 sec. 80 mm/sec; 315 N; 0,97 sec.
-30 88 mm/sec; 177 N; 0,83 sec. 106 mm/sec; 336 N; 1,03 sec.
-60 106 mm/sec; 204 N; 0,80 sec. 59 mm/sec;