Steady headwind display with conditional angular rate-switching control

Abstract

Abstract-This research creates a steady headwind at a user position in the scaled Treadport Active Wind Tunnel (TPAWT). The TPAWT adds a wind display system to the previously developed Treadport virtual environment, and this research builds upon prior work to provide improved control of headwind angle at the user position. Key to this research is the addition of a negative pressure plenum at the rear of the treadport to improve nominal flow stability. The previous controller based upon the small gain theorem with a dynamic extension is then modified to provide wind angle feedback control. A conditional angular rate-switching controller is added to reduce wind angle oscillations at the user. A vorticity-meter is developed to assure that the wind flow is centered at the user position. As a result, this research reduces wind angle error by 75% compared to previous work.

Combined wind speed and angle control in a virtual environment using a static observer

“…In this paper, we combine the input-output feedback controller for wind speed developed in [3] and the feedback controller for wind angle developed in [4] as shown in Fig. 5.…”

“…In order to resolve the rapid nonlinear oscillations of wind angle, the Conditional Angular Rate Switching controller [4], shown in Fig. 5 is used.…”

“…The Treadport Virtual Environment [1] already has a locomotion interface, which allows the user to walk through the virtual environment while viewing realistic rendering on a 180 o CAVE-like display provided by visual screens on the front and the sides. Current works [2][3][4] on augmenting the haptic interface to the original Treadport Virtual Environment [1], termed TreadPort Active Wind Tunnel (TPAWT) involve creating wind flow at the user. A haptic interface improves the sense of immersion for the user [5].…”

“…An air column flows between two counter-rotating vortices towards the user. In [4], a return plenum shown in Fig. 2, is augmented to the scaled model to stabilize wind flow and allow input-output control of wind angle using a version of Small Gain Theorem (SGT) [6] and dynamic extension in combination with a conditional angular rate switching control.…”

“…We incorporate the static observer in the speed controller developed in [3], combine it with the headwind angle controller from [4] and achieve simultaneous wind speed and headwind angle control at the user. From [4] and Fig. 2, observe that the headwind flow diverges at the user.…”