Electricity: motive power systems – Plural – diverse or diversely controlled electric motors
Reexamination Certificate
2001-03-10
2002-07-30
Masih, Karen (Department: 2837)
Electricity: motive power systems
Plural, diverse or diversely controlled electric motors
C318S625000, C318S068000, C180S065510
Reexamination Certificate
active
06426600
ABSTRACT:
STATEMENT RE FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
SEQUENCE LISTING
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to user-actuated control of apparatus. More particularly, the present invention relates to proportional control of rotary and/or linear actuators by body-component-actuated transducers.
2. Description of the Related Art
Control of linear and rotary actuators often includes the requirement that rotational speeds of rotary actuators or linear velocities of linear actuators be precisely controlled.
For instance, when both the speed and steering of a vehicle are controlled by controlling speeds and rotational directions of a pair of electric motors, it is important to separately and precisely control their rotational speeds and differences between their rotational speeds.
Conveyances, or electrically-propelled wheelchairs, provide mobility for a multitude of persons ranging in age from children less than three years old who will never walk, to adults who have been injured in accidents or afflicted with a debilitating illness to elderly people who have acquired infirmities as they have aged.
To these people, their freedom of mobility, and to a large extent their ability to be productive citizens in society, depend upon the mobility afforded by a power wheelchair. Included in this large group of people are some who lack either the use of limb or the motor skills to use the kinds of controls common on power wheelchairs.
Typically, power wheelchairs have been propelled by separate electric motors drivingly connected to left and right wheels of the wheelchair.
By controlling both the equivalent voltage and polarity to the motors, control of forward and reverse directions, speeds, and steering have been controlled. This control of steering includes turns in which the wheelchair pivots around one wheel, and pivot turns in which the wheels rotate in opposite directions at the same or unequal speeds.
Typical control of electrically-propelled wheelchairs has been by an X-Y input device in which a joystick is manually positioned with respect to X and Y axes to selectively provide mechanical inputs to transducers.
While some degree of control can be achieved by simple on-off and forward-reverse control of the driving wheel motors, and while a severely handicapped person may be grateful for the freedom and the personal achievement, on-off controls severely limit the speed, maneuverability, and controllability of the wheelchair.
Perhaps more importantly, this type of simplistic control fails in an area that can be more important to a handicapped person. By failing to allow him to control speeds and steering proportionally, it fails to allow him to use his full physical and mental capabilities.
A problem in achieving satisfactory control of a wheelchair by joystick control has been hand tremors of the user. Lautzenhiser et al., in U.S. Pat. No. 5,012,165, solves the problem of hand tremors by integrating signal variations caused by hand tremors, thereby providing an integrated, or averaged, output.
Even for those with good dexterity with at least one hand, skillful control of power wheelchairs by X-Y input devices has not been as easy as would be desired. It has been difficult, even for those with good motor skills, to drive in a straight path and to make minor changes in direction without overcorrecting.
Included in attempts to overcome this steering problem, is Klimo, U.S. Pat. No. 4,634,941, who has provided a diamond-shaped guide to help the user find the joystick position that results in driving a straight path.
Bell, in U.S. Pat. No. 4,667,136, attempted to overcome this steering problem by placing a resistor between the outputs of two potentiometers, to reduce the differences between the two electrical signals, and thereby to reduce steering sensitivity.
While Bell's use of a resistor does achieve a decrease in steering sensitivity, it is important to notice that the decrease in differences between the electrical signals produced by the two potentiometers is linear. That is, a small difference in electrical signals produces a small decrease in the difference between the electrical signals, and larger differences result in proportionally larger decreases in the differences.
When differences between the electrical signals are small, such as when attempting to steer a straight path, a large percentage decrease in the differences in the electrical signals is needed to effectively reduce steering sensitivity, but Bell's resistor provides a relatively small, and therefore insufficient, reduction in the differences between the two electrical signals unless the resistance of Bell's resistor is relatively small.
However, when attempting to make a sharp turn or a pivot turn, and the differences between the electrical signals are large, a relatively low resistance makes a large decrease in the differences in the electrical signals, thereby decreasing steering sensitivity so severely that it is impossible to effect sharp turns and pivot turns.
Therefore, the use of any fixed resistance that adequately reduces sensitivity for steering a straight path, so severely reduces the difference between the two electrical signals when differences between the signals are large that it is impossible to make sharp turns or pivot turns.
Lautzenhiser, in U.S. Pat. No. 5,635,807 solves the problem of difficult steering control. Instead of allowing the high-side signal to be reduced by flowing through a resistor to the low-side, as taught by Bell, differences in the two control signals are reduced as an inverse, nonlinear, and steady-state function of the differences in the two control signals.
Prior to the teaching of Lautzenhiser as discussed in the preceding paragraph, not only has manual control of a joystick been difficult for many handicapped persons, it has been impossible for others. For those lacking the physical capability of using a joystick, various devices have been proposed.
Witney et al., in U.S. Pat. No. 4,323,829, disclose a “waffle board” control. In use, pressing fingers on selective portions of the horizontally-disposed “waffle board” provides control of speed and steering of a wheelchair.
Others have proposed controls that are actuated by body components other than a hand of the user. Glaser et al., in U.S. Pat. No. 4,523,769, teach a wheelchair in which the feet are used to achieve control of speeds and steering of a wheelchair. The footrests are moveable to positions wherein drive pawls are engaged, providing on-off control of the speeds of each motor.
Mogle, in U.S. Pat. No. 3,965,402, teaches a headrest proportional control. Although his device appears to be tedious to use because of constriction of the user by the headrest control, it seems to advance the art to some degree. Miller, III, in U.S. Pat. No. 4,093,037, also teaches a headrest control for wheelchairs.
Brown et al., in U.S. Pat. No. 4,078,627, teach a chin rest, and control of a wheelchair by chin movement. This device appears to be even more constrictive than those of Mogle and Miller, III.
A still more constrictive device is the “sip and puff” device taught by Muller in U.S. Pat. No. 4,865,610. In addition, it is highly impractical for those who depend upon a ventilator for breathing.
Loveless et al., in U.S. Pat. No. 4,260,035, teach chin control in which the transducers may be mechanical or optical, with the optical device being somewhat less constrictive. Fetchko, in U.S. Pat. No. 4,486,630, teaches a device in which the user wears a rather complex and cumbersome headset, and control of various devices is achieved by moving the user's jaw or eyebrows.
Johnston, U.S. Pat. No. 4,281,734, frees the user of the cumbersome headset of Fetchko by teaching the use of light sensors that are attached behind the head of the user. Simmons et al., in U.S. Pat. No. 3,993,154, seem to advance the art by teaching apparatus in which an energy field is directed toward the user's body, and a field pickup element senses change
Lautzenhiser John L.
Lautzenhiser Lloyd L.
Magitek.com,LLC
Masih Karen
Miller Wendell E.
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