Material or article handling – Article manipulator moves analogous with human hand – finger,... – Electric or fluid motor drive for manipulator
Reexamination Certificate
2001-06-29
2002-08-20
Olszewski, Robert P. (Department: 2167)
Material or article handling
Article manipulator moves analogous with human hand, finger,...
Electric or fluid motor drive for manipulator
C414S730000, C340S407100, C703S005000, C703S007000, C600S595000
Reexamination Certificate
active
06435794
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to human machine interfaces, particularly to those interfaces that measure human body positions and display forces to the human operator.
BACKGROUND OF THE INVENTION
Teleoperation refers to a mode of enhanced human control of remote manipulators. In teleoperation, the human operator utilizes a controller device or “master” in combination with his or her body to control the positions of a remote manipulator or “slave” device. The slave or remote manipulator may be a physical robotic gripper, or a virtual computer generated representation of a human body part, most commonly a human hand. In teleoperation, relative positions or forces of the human body are measured at the master and used to control the remote manipulator positions or forces at the slave. Most often positions are measured at the master and used to control the slave positions, and forces are measured at the slave to be displayed to the human operator through the master. In virtual slave environments, the forces are calculated within the virtual reality computer, while in robotic slave environments, the forces of contact between the slave and any object are measured via forces sensors. One human body part that is very well suited for teleoperation control is the human hand. The hand is most commonly used for highly dexterous manipulation tasks in interaction with our everyday surroundings. Because of this human ability several instrumented master devices have been developed in order to measure the time varying positions of the fingers on the human hand, utilizing the position data to control the finger positions of a virtual or robotic slave hand. Some of these devices have been developed to also provide a means for display of forces that occur in the slave environment to the human operator in the master environment. However the prior art is lacking in the simplicity necessary to allow large scale acceptance of this method of interaction, and/or are not capable of displaying force sensations that match those of real world interactions, especially at the high rate of speed these sensations are processed by the human operator.
The present invention relates to a master device capable of measurement of finger angular position and display of forces of contact experienced by the slave to the human operator. Both position measurement and force display are performed locally to the fingertips with respect to the hand. Many methods exist for measuring the global position and orientation of the human hand and using this data to control the position and orientation of the slave hand. Some methods include: attaching the master of the present invention to a joystick, attaching the master of the present invention to a six degree of freedom robot, or the use of a magnetic type tracking device.
The research in the area of local finger position measurement and force display dates back at least as far as 1963, when Jones and Thousand (U.S. Pat. No. 3,263,824) disclosed a device for providing the operator with a kinesthetic sensation which simulates the force being placed on a object controlled by the manipulator. This device consisted of an air bladder attached to the interior finger surfaces of an operator worn glove. The bladder is controlled to inflate at a pressure proportional to the force measured at a remote robotic manipulator. One deficiency in this device is that it is difficult to apply and remove the bladder pressure at very high frequencies necessary to approximate real time interaction. A second drawback is that the bladder material gathers and bunches up as the operator moves their finger from the extended position toward the palm to the retracted position, not permitting full finger-retraction.
Previous attempts at hand mounted single controlled degree of freedom finger tip force displays have provided forces that vary widely with finger bend angle, and/or are able to represent motion through only a fraction of the 180 degrees of real finger bend motion. For example, the palm mounted air cylinder method of Burdea's (1996) Rutger's Master I and Rutger's Master II provide a force at an angle that widely varies with finger bend angle, and can only represent finger bend from approximately 40 to 90 degrees. The cylinder mounted to the palm also provides a force to the operator's palm for all slave/object interactions, even those in which there is no contact between an object and the slave palm area. The angle of applied force also varies with finger bend angle for the tendon approach of Kramer (U.S. Pat. No. 5,184,319). The Kramer device uses tendons that pass along the outer surface of the operator's hand, thus utilizing the outer surface of the knuckles as a fulcrum point for application of forces to resist finger retraction. With this approach, the tendon force must be very high to restrict finger retraction, and consequently, it is difficult to maintain the tendons in their desired position. Additionally with the Kramer device, the forces applied to the operator's fingertips are substantially directed along the longitudinal axis of the finger distal digit, when the finger approaches the fully extended and fully retracted positions. In contrast, during real grasp operations, the force of contact between grasped objects and the human fingers are substantially normal (perpendicular) to the longitudinal axis of the finger distal digit. The tendon with additional moment arm modification of Virtual Technologies (1997), more closely provides normal direction fingertip forces throughout full finger bend range, but at the expense of applying ghost forces to the back of the second finger phalange.
Other approaches to finger force display masters employ devices that do not permit a large workspace for hand motion, attach heavy actuators to the human body, provide forces at widely varying angles with respect to the longitudinal axis of the distal finger digit, limit finger bend position to only a small portion of its full range, or are very expensive to manufacture. Additionally prior approaches fail to provide a force display signal to the operator at a high enough rate of speed to simulate real world touch sensations, thus resulting in jerky or lively object sensations, unstable oscillatory force applications, or require very slow human command motions.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the invention to provide a means of displaying forces substantially normal to the fingertip through out the full range of finger bend, for use in robotic and virtual reality environments, without the aforementioned shortcomings. The application of forces will permit simulation of grasping tasks, touching surfaces with the fingers extended, deforming virtual object shapes and simulating the removal of material from a virtual body such as virtual sculpting.
It is an object of the present invention to provide a master device which is of simple construction and requires the minimum number of controlled degrees of freedom to accurately measure fingertip positions and provide force display thereto, and thus require the minimum number of measured control variables and the minimum number of actuators.
It is an object of the present invention to provide a device for force display that without modification can be effectively used by people with a wide range of hand sizes.
It is also an object of the invention to provide to provide a master device for teleoperation that exhibits a high degree of transparency to the operator, such that unobstructed motion of the slave, is represented to the operator as free unobstructed motion of the fingers throughout a large range of finger motion.
It is another object of the invention to provide a master device that is portable and thus provides the operator with a large workspace.
It is a further object of the invention to provide a master device that is comfortable to wear for long periods of time and thus is light weight, has low apparent (to the user) inertia, and yet maintains a high stiffness so as to provide rea
O'Connor Gerald J.
Olszewski Robert P.
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