| Historically robotic manipulators are built to interact with objects and their environment, not with humans. Presently robots are being further integrated into our lives for human power augmentation, as robotic nurses, haptic interfaces, and assistive devices for physical therapy. With over one billion people worldwide suffering from neurological disorders, and ;Even with their benefits, passively actuated haptic robots have not been considered competitors with motor driven haptic displays because they are perceived to only impede motion or used solely as additional physical damping to increase the range of stability for rendering impedance. This dissertation aims to change this definition and demonstrate that display of high fidelity and rich virtual interactions are possible while preserving safety.;To accomplish this goal we have designed and built the Brake Actuated Manipulator along with its controllers and virtual environments. The Brake Actuated Manipulator is used as a tool for investigating and expanding the boundaries of passively actuated devices in a large three dimensional workspace. This dissertation explores how these boundaries can be surmounted through mechanics, controller design, and haptic rendering. In addition, the importance of human perception within the control system is recognized and used to expand the capabilities of passively actuated devices.;The major contributions are the control and rendering strategies which produce transparent interaction with a variety of virtual environments, as well as the evolution of perceptual manipulation as an additional element to manipulate movement. These outcomes directly impact the capabilities of passively actuated devices for haptic display while retaining safety in a large workspace.;Assistive robots require intimate physical human robot interaction. With this intimate contact comes the need for a redefinition of safety. The chance that such devices can physically strike, overpower, or otherwise injure a human during interaction is unacceptable. One solution to this problem is passive actuation. Passive actuation enables safe large workspaces with low effective inertia, stable stiff virtual constraints, low power requirements, and robust wear characteristics. |
