Doubledrive imprint download

Sunday 12 September Monday 13 September Tuesday 14 September Wednesday 15 September Thursday 16 September Friday 17 September Saturday 18 September Sunday 19 September Monday 20 September Tuesday 21 September Wednesday 22 September Thursday 23 September Friday 24 September Saturday 25 September Sunday 26 September Monday 27 September Tuesday 28 September Wednesday 29 September Thursday 30 September Friday 1 October Saturday 2 October Sunday 3 October Monday 4 October Tuesday 5 October Wednesday 6 October Thursday 7 October Friday 8 October Saturday 9 October Sunday 10 October Monday 11 October Tuesday 12 October Wednesday 13 October Thursday 14 October Friday 15 October Saturday 16 October Sunday 17 October Monday 18 October Tuesday 19 October Wednesday 20 October Thursday 21 October Friday 22 October Saturday 23 October Sunday 24 October Monday 25 October Tuesday 26 October Wednesday 27 October Thursday 28 October Friday 29 October Saturday 30 October Sunday 31 October Monday 1 November Tuesday 2 November Wednesday 3 November Thursday 4 November Friday 5 November Saturday 6 November Sunday 7 November Monday 8 November Tuesday 9 November Wednesday 10 November Thursday 11 November Friday 12 November Saturday 13 November Sunday 14 November Monday 15 November Tuesday 16 November Wednesday 17 November Thursday 18 November Friday 19 November Saturday 20 November Sunday 21 November Monday 22 November In order to reduce the influence of friction on the feed system, a lot of research has been done on friction modeling and friction compensation Michael et al.

The LuGre model, put forward by Canudas et al. This model can describe the main characteristics of dynamic friction, including the Stribeck effect, hysteresis, spring characteristics of static friction and changing sliding friction.

Liu et al. The distributed component friction model of a feed drive system, which was proposed by Lee et al. Hongbiao et al. To reduce the influence of friction on the feed system, Lee et al. Besides, Han et al. However, the friction compensation method, based on the friction model proposed above, cannot avoid the nonlinear friction disturbance when the table is running at low speed for the ball screw feed system.

In this paper, a novel differential double-drive feed system DDFS is developed to minimize the influence of the nonlinear friction at the ball screw pair of a linear feed system operating at low speed. In the DDFS, the screw and the nut are both driven by permanent magnet synchronous motors PMSMs that rotate in the same direction at nearly equal high speed, which are superimposed by the ball screw pair to obtain low-velocity linear motion of the table.

In this way, it ensures that the driven table travels at low velocity while the two motors are allowed to rotate at high speed. Compared with the CDFS, the DDFS can reduce the influence of the nonlinear friction at the ball screw pair, thereby improving the speed smoothness at low-speed operation. The remainder of this paper is arranged as follows. The friction model and friction parameter identification are described in Sect. The experimental results to validate the effectiveness of the proposed method are in Sect.

The paper is concluded in Sect. In the CDFS, the screw shaft is driven by a servo motor through a coupling, and the rotary motion of the motor is converted into the linear motion of the table. The schematic diagram for the structure of the DDFS based on the nut driven ball screw pair is illustrated in Fig. In the DDFS, the screw shaft and screw nut, both driven by PMSMs, rotate in the same direction at high speed and are superimposed though the ball screw pair to obtain low-velocity of the table.

This design ensures that the driven table travels at low velocity with the two motors rotating at high speed. The low velocity of the table is obtained, and the crawling zone for the motors at low speed is avoided by superimposing two PMSM rotating speeds at high speed by the ball screw pair Du et al. To avoid the low-speed crawling area of a single motor, higher speeds for the screw and the hollow motors are given in the DDFS. T sf is the equivalent friction torque at the screw motor shaft, including the friction torque at the ball screw, the screw support bearing and the screw motor.

T sd is the output torque generated by the interaction between the screw shaft and nut. J s is the equivalent moment at the screw motor shaft, including the screw motor shaft, coupling and screw shaft. F sd is the driving force acting on the table.

F f1 is the friction force at the table. The axial rigidity of the screw is shown in Eq. The axial displacement x t1 of the table can be expressed as shown in Eq. It is assumed that the rotation angle of the screw motor is larger than that of the hollow motor, and the torsional deformation between the screw motor and the screw shaft and between the hollow motor and the screw nut are ignored at the same time.

T nf is the friction torque equivalent to the hollow motor shaft, including the friction torque at the ball screw, the nut support bearing and the hollow motor. T d is the output torque generated by the interaction between the screw shaft and nut. J n is the moment of inertia equivalent to the hollow motor shaft, including the hollow motor shaft, screw nut and connecting flange.

In the DDFS, friction can be subdivided into the following three parts: friction torque equivalent to the screw motor shaft, including the friction torque at the screw motor bearing, the screw support bearing, and the ball screw; the friction torque equivalent to the hollow motor shaft, including the friction torque of the hollow motor bearing and the nut bearing; and the friction force at the table. The friction modeling of the screw motor shaft is shown in Eq.

The friction modeling of the hollow motor shaft is shown in Eq. The friction modeling of the linear guide is shown in Eq. In order to compare the friction parameters between the screw drive shaft, the nut drive shaft and the linear guide, we divided the torque defined in Eqs. The identification results of the friction parameters are shown in Table 1 according to the following references: Liu et al.

The direction away from the screw motor is positive, and the direction close to the screw motor is negative in Table 1. To compare and study the critical creeping speed of the table by using different driving methods, we set the same control parameters for the two motors. Figure 6 shows the velocity of the table at different velocities for the CDFS. Figure 6a shows that the table crawls at 1. This is because the command velocity of the table is lower than the Stribeck velocity of the table.

Figure 6b shows that the velocity of the table has stabilized at 1. Therefore, the critical creeping velocity of the table is about 1.

Figure 7 shows the speed of the table at 1. The hollow motor keeps a constant speed v n all the time in Fig. Figure 7 shows that when the velocity of the table is 1. Figure 7 shows that when the speed of the hollow motor is greater than 10 times the critical creeping speed of the CDFS, there is almost no significant change in the acceleration stage velocity and adjustment time of the table for the DDFS.

Friday 13 August Saturday 14 August Sunday 15 August Monday 16 August Tuesday 17 August Wednesday 18 August Thursday 19 August Friday 20 August Saturday 21 August Sunday 22 August Monday 23 August Tuesday 24 August Wednesday 25 August Thursday 26 August Friday 27 August Saturday 28 August Sunday 29 August Monday 30 August Tuesday 31 August Wednesday 1 September Thursday 2 September Friday 3 September Saturday 4 September Sunday 5 September Monday 6 September Tuesday 7 September Wednesday 8 September Thursday 9 September Friday 10 September Saturday 11 September Sunday 12 September Monday 13 September Tuesday 14 September Wednesday 15 September Thursday 16 September Friday 17 September Saturday 18 September Sunday 19 September Monday 20 September Tuesday 21 September Wednesday 22 September Thursday 23 September Friday 24 September Saturday 25 September Sunday 26 September Monday 27 September Tuesday 28 September Wednesday 29 September Thursday 30 September Friday 1 October Saturday 2 October Sunday 3 October Monday 4 October Tuesday 5 October Wednesday 6 October Thursday 7 October Friday 8 October Saturday 9 October Sunday 10 October Monday 11 October Tuesday 12 October Wednesday 13 October Thursday 14 October Friday 15 October Saturday 16 October Sunday 17 October Monday 18 October Tuesday 19 October Wednesday 20 October Thursday 21 October Friday 22 October Saturday 23 October