Non-contact tape tension measurement and correlation of lateral tape motion and tape tension transients

2006 ◽  
Vol 12 (9) ◽  
pp. 814-821 ◽  
Author(s):  
Bart Raeymaekers ◽  
Ryan J. Taylor ◽  
Frank E. Talke
2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Bart Raeymaekers ◽  
Frank E. Talke

The sources of lateral tape motion in a tape drive are reviewed. Currently used measurement methods and models for lateral tape motion are analyzed and compared. The effect of roller run-out, tape edge contact, and tape tension transients on lateral tape motion is discussed. A dual stage actuator tape head is investigated to improve track-following capability and increase the track density on a magnetic tape.


1990 ◽  
Vol 258 (4) ◽  
pp. H1087-H1096
Author(s):  
P. J. Reiser ◽  
B. D. Lindley

Isolated frog atrial trabeculae were activated using the method of Na+ withdrawal to induce contractures of relatively steady tension. External Na+ concentration [( Na+]o) during contractures was varied between 0.25 and 45 mM. Isometric contracture tension was measured at cold (4 degrees C) and warm (20 degrees C) temperatures. In addition, rapid temperature jumps (complete in approximately 400 ms) were imposed during cold contractures, resulting in tension transients that consisted of an initial increase in tension followed by a decrease, the latter phase being greater at small and moderate reductions in [Na+]o. Peak contracture tension varied with relative muscle length. The trabeculae became more sensitive with stretch to Na+ withdrawal at 20 degrees C and generated relatively greater tensions at a given [Na+]o. The initial tension increase after a temperature jump was directly proportional to the peak contracture tension immediately preceding the increase in temperature and was therefore interpreted as reflecting an effect of the higher temperature on the attached force-generating cross bridges. The effects of cold and warm steady temperatures and temperature jumps during isometric twitches were also studied. Peak twitch tension varied inversely with temperature (stimulus frequency = 0.2 Hz). In contrast, temperature jumps imposed during the rising phase of twitches at a steady cold temperature (approximately 4 degrees C) resulted in a large initial increase in tension followed by relaxation at a rate that was characteristic of the elevated temperature. The results suggest that, at the warmer temperature (approximately 20 degrees C), activation (i.e., number of attached cross bridges) of the myocardium is significantly less than maximal during the twitch response. The dependence of the tension vs. [Na+]o curves and the tension transients resulting from the temperature jumps on relative muscle length provide evidence for a length dependency of contractile activation in intact atrial trabeculae under conditions of steady-state tension development.


Author(s):  
Uwe Boettcher ◽  
Bart Raeymaekers ◽  
Raymond A. de Callafon ◽  
Frank E. Talke

We have implemented the design of a dual-stage actuator tape head for enhanced reduction of lateral tape motion (LTM) disturbance. Our design consists of a conventional voice coil motor (VCM) and a micro-actuator for coarse and fine positioning, respectively. The micro-actuator, which is mounted on the VCM, uses a piezo crystal and allows following LTM up to the kHz regime, while the VCM follows low frequency LTM. Using step response measurements and a realization algorithm, we have created a multi-input discrete-time model of the dual-stage actuator. Based on the model, we designed and implemented a dual-stage controller, using a dual-input single-output approach based on a PQ method. The dual-stage controller controls the position of both actuators and enables an increased track-following bandwidth along with a control signal that is smaller in magnitude than that for a conventional single-stage tape head.


2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Hankang Yang ◽  
Johan B. C. Engelen ◽  
Walter Häberle ◽  
Mark A. Lantz ◽  
Sinan Müftü

Effects of friction forces on the lateral dynamics of a magnetic recording tape, wrapped around a grooved roller are investigated experimentally and theoretically. Tape is modeled as a viscoelastic, tensioned beam subjected to belt-wrap pressure and friction forces. Including the effects of stick and slip and velocity dependence of the friction force render the tape's equation of motion nonlinear. In the experiments, tape was wrapped under tension around a grooved roller in a customized tape path. The tape running speed along the axial direction was set to zero, thus only the lateral effects were studied. The grooved roller was attached to an actuator, which moved the roller across the tape. Tests were performed in slow and fast actuation modes. The slow mode was used to identify an effective static, or breakaway, friction coefficient. In the fast mode, the roller was actuated with a 50 Hz sinusoid. The same effective friction coefficient was deduced from the fast actuation mode tests. This test mode also revealed a periodic stick–slip phenomenon. The stick-to-slip and slip-to-stick transitions occurred when the tape vibration speed matched the roller actuation speed. Both experiments and theory show that upon slip, tape vibrates primarily at its natural frequency, and vibrations are attenuated relatively fast due to frictional and internal damping. This work also shows that an effective friction coefficient can be described that captures the complex interactions in lateral tape motion (LTM) over a grooved roller.


2005 ◽  
Vol 11 (8-10) ◽  
pp. 1158-1165 ◽  
Author(s):  
Jason H. Wang ◽  
Frank E. Talke

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