6 research outputs found
Docking Haptics: Extending the Reach of Haptics by Dynamic Combinations of Grounded and Worn Devices
Grounded haptic devices can provide a variety of forces but have limited
working volumes. Wearable haptic devices operate over a large volume but are
relatively restricted in the types of stimuli they can generate. We propose the
concept of docking haptics, in which different types of haptic devices are
dynamically docked at run time. This creates a hybrid system, where the
potential feedback depends on the user's location. We show a prototype docking
haptic workspace, combining a grounded six degree-of-freedom force feedback arm
with a hand exoskeleton. We are able to create the sensation of weight on the
hand when it is within reach of the grounded device, but away from the grounded
device, hand-referenced force feedback is still available. A user study
demonstrates that users can successfully discriminate weight when using docking
haptics, but not with the exoskeleton alone. Such hybrid systems would be able
to change configuration further, for example docking two grounded devices to a
hand in order to deliver twice the force, or extend the working volume. We
suggest that the docking haptics concept can thus extend the practical utility
of haptics in user interfaces
Design and Analysis of a Fast Steering Mirror for Precision Laser Beams Steering
Precision laser beam steering is critical in numerous applications. Also, precise pointing of laser beams is essential in challenging environments. The optical signal may be deflected, drift and wander due to environmental influences. The core problem of steering performances is to deal with the jitter disturbance. Based on the analysis of the beam angle steering system, some important factors to design the structure of a Fast Steering Mirror (FSM) and the layout of laser optics steering system are presented. Flexure hinges with compliant mechanisms are used to build the FSM structure. A 4-quadrant detector is used as the sensor for the incoming light. A design of the developed control loop and concepts of the FSM model are discussed. A comparison between the measured gain response and the simulation model of the FSM reveals similarity between the theoretical simulation model and the real system, and offers a way to improve the model to better resemble the real system. A laser beam jitter control test bed is also introduced to improve jitter control techniques
A Study on Dynamic Stiffening of a Rotating Beam with a Tip Mass
Flexible structure, Dynamic stiffening, Assumed mode method, Flexible beam
This paper presents a dynamic model of a rotating beam with a tip mass undergoing large angle, high speed maneuvering. This type of model may also be useful in modeling, analysis and development of various inertial sensors and transducers with similar operating principles. With the consideration of the second-order term of the coupling deformation field, the complete first-order approximated model (CFOAM) of a flexible spacecraft system is developed by using assumed mode method (AMM) and Lagrangian principle. A first-order approximated model (FOAM) is obtained by neglecting the high order terms of the generalized coordinates in CFOAM. A lower order simplified first-order approximated model (SFOAM) is derived by deleting the terms related to the axial deformation. Numerical simulations and theoretical analysis show that: (i) the second-order term has a significant effect on the dynamic characteristics of the system and the dynamic stiffening is accounted for, while the traditional linear approximated model (TLAM) presents invalid simulation results; (ii) the end mass has a ‘stiffening’ effect on the flexible system in FOAM, but a ‘softening’ effect in TLAM; and (iii) the SFOAM describes the dynamic behavior well and can be used for controller design