Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
2000-11-06
2001-10-23
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
C273S14800B, C341S020000
Reexamination Certificate
active
06307285
ABSTRACT:
BACKGROUND
This invention relates to actuators and mechanisms which can generate motion and force output. It relates more specifically to devices that use electromagnetic forces to generate actuator output. It relates to computer operated machines. It relates to machines that act as an interface between a human user and machines of all types, including computers and machine tools.
This invention relates to computer controlled machines, where a computer specifies the desired performance of a mechanism. The computer may use sensor feedback, where sensor measurement of a mechanism is used by the computer to control the mechanism. A computer may also use sensor-less, or open-loop control, where the computer controls the mechanism without sensor feedback. One such control method is open-loop stiffness control, where the stiffness of a mechanism is specified, without sensor measurement of force applied to or position of the mechanism.
Computer controlled mechanism have a wide variety of applications, including robotics, automatic machining, consumer products, and medical devices. In lieu of a computer control, actuators can be controlled from simple controllers, signals from other mechanisms, or directly by humans (or even animals).
A specific application of this invention is for actuated human interface devices. Many machines are controlled, either directly or indirectly, by a human operator. The interface through which the operator controls the machine and receives information from the machine should be as easy to use as possible. The user may input commands to, receive information from, and otherwise interact with such machines through various devices, such as a lever, joystick, foot pedal, mouse (having buttons and a tracking mechanism), exoskeleton, keyboard, touch screen, digitized pad or tablet, head mouse, haptic force reflecting mechanism, etc. In general the component that the user physically touches is referred to as an “interface member.”
In certain instances it is desirable that the interface device be actuated so that forces can be applied by the mechanism onto the user. A system that accomplishes this is sometimes referred to as a “force reflecting” system or a “haptic” interface, because it relates to the human system of touch.
An actuated interface device can function as both an input and output device. The user may input signals into a computer by manipulating the interface device, and the computer may output signals by imparting force and motion onto the user through the interface device. Thus, an interface member may also be referred to as an output device, or a display, etc. The format of the input and output signals can be in terms of force and torque, and position and rotation (and their time derivatives including velocity and acceleration).
Force reflecting interfaces are surveyed and described in general by Burdea, Grigore, in
Force and Touch Feedback For Virtual Reality,
John Wiley & Sons, Inc., New York (1996).
One use of actuated human interface devices is for telepresence and in teleoperated systems. Telepresence is when a person or teleoperator uses technology to mediate interactions with a remote physical environment. In the master/slave configuration, the user manipulates a “master” input device in the user's local environment. There may be a “slave” robot, typically in a different, non-local environment, which moves in accordance to the user's manipulations. The configuration of the master device may or may not conform to some degree to the conformation of the slave device. Teleoperation is useful in applications where direct interactions might be impossible because of physical conditions which are hazardous to humans, for example working with radioactive waste, or working in an underwater environment a mile deep. Other physically impossible conditions might be related to physical scale, such as nanomanipulation of a molecule, or the macromanipulation of an enormous crane. An example of telepresence is remote surgery, in which a surgeon uses a force-feedback scalpel at one location connected to a robotic scalpel in a surgical suite at another location. The surgeon's locally generated forces are transmitted to a remote actuator, and the remote forces generated by that actuator in contact with the patient are “fed back” to the surgeon's hand held scalpel, creating an effective, telemanipulative operation.
Another application of actuated human interface devices is “virtual presence.” In virtual presence human operators control and interact with “virtual” machines and environments, which are not physical, but rather are “embodied” or reside in a computer model. A virtual environment relates to an environment that bears some mapping to an actual physical instance of the environment. For instance, a computer representation of a real slave environment is considered herein to be a virtual environment that corresponds to the physical slave environment. Virtual presence may also be used for semi-autonomous control of interaction with physical objects. This might occur when communications lag time between a person and the remote environment is too long, such as when operating a remote device on the planet Mars.
One objective of an actuated interface is to increase the realism of human interaction with virtual representation of objects by expanding the scope of human sensation and perception to include physical characteristics such as interaction forces with an object; and for movable objects; heft and inertia. This increase in realism allows humans to perform tasks better by leveraging human motor skills, and a heightened experience related to the interaction.
Actuated interface devices can be used to convey general information to the user. The force interactions may not necessarily correspond to a remote slave environment, or to a virtual environment mapped from a physical environment. For example a force interaction may be used to indicate the misspelling of a word in a word processing program. Actuated interface devices may also be used in computer games, by providing force-feedback to the users.
This invention also relates to actuators and mechanisms with numerous Degrees of Freedom (DOF). Each rigid body may have up to six DOF including translation and rotation. Moreover, the interface mechanisms may have numerous rigid members or flexible members. Thus, the overall number of DOF of such a mechanism may be greater than six. For example a master arm may have a hand portion, with several fingers, each with several joints.
For actuators in general, and especially for actuated interface mechanisms, high fidelity is often an important design consideration. A high fidelity actuator will have an output that is as close as possible to the desired output. The fidelity of the output relates to both accuracy in magnitude and in timing. Accordingly, a high fidelity mechanism will have a high bandwidth, and a minimum time delay from the instance that an output is desired and when the actuator responds. To achieve a high fidelity in the magnitude of the output it is desirable to minimize detrimental friction and backlash, which are often inherent in systems with transmissions between the actuators and the interface member.
Much of the engineering design effort related to force-feedback has centered on reducing the costs of present force-feedback input devices and development of software for authoring haptic cues, rather than basic force-feedback actuator design. Many present force-feedback input device rely on traditional motor actuators and closed-loop control, despite their many limitations, such as backlash and limited bandwidth. Therefore, there is a need for a high fidelity, robust, and low-cost actuator for use in these applications.
Known actuators meet many current needs. Most known mechanisms actuate a single DOF with a single powered actuator. However, many of the limbs of humans and animals function by a balancing between two opposed actuators (flexor and extensor muscles), which can be energized independently or simultaneously. Moreove
Delson Nathan J.
Houston John S
Coactive Drive Corporation
Jones Judson H.
Ramirez Nestor
Weissburg Steven J.
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