Power plants – Pressure fluid source and motor – Manipulator for motive fluid control valve having load feel...
Reexamination Certificate
2001-03-15
2003-01-21
Look, Edward K. (Department: 3745)
Power plants
Pressure fluid source and motor
Manipulator for motive fluid control valve having load feel...
C091S434000, C414S005000
Reexamination Certificate
active
06508058
ABSTRACT:
FIELD OF THE INVENTION
This application relates to the field of control of hydraulic and pneumatic apparatus, and the feedback of position and effort exerted by hydraulic apparatus to an operator of such apparatus.
BACKGROUND OF THE INVENTION
Hydraulic and pneumatic powered machines require some means of translating the physical input of an operator into movement of the various members of the machine. Traditionally an operator manipulates the individual members of such a machine using some device (a manipulator) to operate directional valves that supply power to actuators that move each movable member comprising the machine. In the simplest of equipment, an operator is provided with a lever that is connected to a 4 way valve, one such assembly for every axis of motion the machine affords. Pushing or pulling a given lever moves a given machine member about its axis. The operator can also move the levers in sets or multiples to move more than one of the machine members simultaneously about their various axes. Generally, an operator visually inspects the machine to determine the position of the machine members (machine configuration). Feedback to the operator using such a scheme is limited to visual inspection of the machine and what the machine's performance and the operator's experience and his other senses impart to him regarding the conditions of load and resistance during any operation. Furthermore, in the simplest form of control, as the number of axes of movement are multiplied, the ability of the operator to visually inspect the response of the machine to his input and to manipulate multiple valves to move simultaneously about multiple axis becomes increasingly taxed. One example of such complexity is found in machines which are anthropomorphic (a machine the members of which are capable of the same range of motion as an analogous human anatomical feature such as a hand and arm). For a machine to duplicate the range of motion of a human hand and arm would require at least 27 axes of motion, which is probably beyond the ability of even the most skilled operator to operate smoothly if presented with a single lever control for every axis of motion.
Some schemes have been advanced wherein an operator inputs movement to a machine using a manipulator that is designed such that it breaks down the natural movement of the operator's input into motion of multiple machine members along multiple axis and transmits signals activating hydraulic cylinders to move a collection of machine members along a path that corresponds to the operator's movement applied to the manipulator. In such schemes the manipulator performs two functions, one function is to permit the machine to be operated by the use of “natural” or “intuitive” motions, that is controlled without the operator having to translate a desired motion into a series of lever manipulations, and the second function is that it limits the operator's movements to those motions that can be carried out by the machine interfaced to the manipulator. Thus, when manipulating machines that are not anthropomorphic, the manipulator constrains the natural movements of the operator to those which the associated machine can execute while providing the operator with an intuitive interface to the machine.
When manipulating more complex machinery a manipulator provides a method of utilizing intuitive or natural operator movements to control simultaneous motion of a plethera of machine members which would not be feasible to control using simple control schemes. These two aspects of a manipulator make it possible for an operator of lesser training to smoothly operate reasonably simple machinery using intuitive input movements, and at the same time make it possible for an operator of any skill level to control a machine with a larger number of machine members operating about a larger number of axes, than would otherwise be feasible.
One central-advantage of using such a manipulator to control a machine, regardless of the complexity of the machine or skill of the operator is that an operator does not have to mentally translate the motion he or she desires the machine member to make into a movement of several control levers, but has only to move the manipulator in a scale duplicate motion of the one the operator desires the machine to perform. One difficulty inherent in using natural motion lies in the fact that uncontrolled motion can lead to dangerous operating conditions in the vicinity of the machine executing an uncontrolled operator command. An operator requires position and force feedback to operate hydraulically and pneumatically powered equipment safely, particularly if the equipment being operated is much larger or smaller in size than the operator.
The prior art includes a number of schemes that provide load sensing along with positional and rate feedback using pressure and position sensors, differential amplifiers, and torque motors. These devices are employed to effect a system in which the application of hydraulic power to the drive device moving a related machine member is varied depending upon the degree in positional difference between the control element and its corresponding machine member, and the back pressure generated by the torque motors against the control elements varies with the operating pressure supplied to the drive devices.
Prior art systems which have been disclosed to help an operator with visual feedback follow. One such scheme is disclosed in U.S. Pat. No. 5,000,650 to Brewer et. al wherein a system of proximity switches and proximity targets is used to determine the position of machine members in machines comprised of jointed, movable members. The proximity switches are electrically connected to suitable devices to automatically cancel operator input to a control valve which has actuated a machine member once the machine member has reached a particular travel limit. No scheme of feedback to the operator of the control members is disclosed.
Several examples exist wherein complex motions can be input on multiple axis manipulators without the necessity of manipulating a multiplicity of input controls. One example of such a scheme is disclosed in U.S. Pat. No. 5,019,761, a manipulator arm with 6 degrees of freedom is disclosed for one handed manipulation of excavation tools having 6 axis of motion. It is claimed that this type of manipulator can be employed with any control and feedback scheme known in the prior art. No specific methods of control and feedback are disclosed.
In U.S. Pat. No. 5,002,454 to Hadank et.al. there is disclosed a configuration of multiple axis control levers which generate electrical signals in response to operator hand movements that are said to provide a more intuitive operation of equipment having multiple axis machine members. No specific scheme of converting the electrical signals into operation of the machine members is disclosed and no scheme of feedback to the control levers is disclosed.
U.S. Pat. No. 3,880,304 to Strickland discloses a system of valve actuating elements mounted on a scale model representation of a digging apparatus. The digging apparatus is comprised of a dipper, a dipper arm, and a crowd arm mounted on a rotating base (to use the descriptive language of the '304 patent). The valve actuating elements each ultimately control a hydraulic directional control valve that supplies hydraulic pressure to a hydraulic actuator which in turn moves one of the members of the digging apparatus. The components of the scale model are mechanically linked by a system of cables, chain drives, and levers to the components of the digging apparatus which they model in such a manner that the motion of the digging apparatus is transmitted to the scale model components. In this manner, the configuration of the digging apparatus is mapped onto the model components, giving a visual readout of the configuration of the digging apparatus to an operator. A system of control knobs and levers is arranged about the scale model of the digging apparatus such that by moving them
Leslie Michael
Look Edward K.
Martin Rick
Patent Law Offices of Rick Martin P.C.
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