1. Field of the Invention
The present invention relates generally to manually controlling an apparatus and/or a multiplexer. More particularly, the present invention relates to controlling an apparatus and/or a multiplexer by signals that preferably include proportional-output signals, rate-of-change signals, and open/closed output signals.
2. Description of the Related Art
In recent years there has been an increasing awareness of the importance, not only providing for the needs of handicapped persons, but also of utilizing them as productive members of society, rather than keeping them partially or wholly dependent upon others.
Fortunately, this enlightened view has coincided with giant strides in technology, particularly electronics and computer-based technology, and this increase in technology has been reflected by giant strides in electrically-propelled wheelchairs.
The prior art includes electrically-propelled wheelchairs in which control of start, stop, and steering has been achieved by manually-actuated X-Y transducers, commonly called “joysticks.”
Lautzenhiser et al., in U.S. Pat. No. 4,906,906, issued 6 Mar. 1990, and in U.S. Pat. No. 4,978,899, issued 18 Dec. 1990, teach wheelchairs that are propelled by pulse-width-modulated voltages, that are dynamically braked by shorting the motors, that are made freewheeling without the expense and complexity of a clutch, and in which tremor control is provided, so that those who have hand tremors can easily and accurately control power wheelchairs.
The prior art includes attempts to control wheelchairs by sipping or puffing on a tube. However, controllability of sip-and-puff units has been marginal, especially for those who depend upon a respirator or ventilator for breathing, since they can puff into a tube only while exhaling, and sipping is even more difficult.
In U.S. Pat. No. 5,635,807, which issued on 3 Jun. 1997, Lautzenhiser teaches electric control systems that provide nonlinear relationships between X-Y mechanical inputs and resultant differential speeds of two propulsion motors. These nonlinear relationships between X-Y mechanical inputs and electrical outputs allow many handicapped persons, who otherwise would be limited to sip-and-puff systems, to control a wheelchair by joystick movement.
Perhaps even more significantly, when a joystick is replaced with two tiny transducers or input devices that are mounted to a person's head, or to an other body member, these nonlinear relationships allow easy and accurate control of both speed and steering of power wheelchairs by means of body-component movements. For instance, a person who is paralyzed from the neck down can perform all control functions of an electrically propelled wheelchair except for connecting and disconnecting power to the system.
In U.S. Pat. No. 5,635,807, Lautzenhiser also provides adjustable transducer sensitivity, steering sensitivity control that is adjustable, selectively-adjustable signal limiting so that maximum speeds can be selectively adjusted, and overrange shutdown.
In U.S. patent application Ser. No. 09/652,395, filed 31 Aug. 2000, Lautzenhiser et al. teach a tilt-axis X-Y input device that may be mounted to a body component, such as the head or a hand of a user, null compensators that automatically compensate for errors in attaching the X-Y input device to a head or other body component, a null-width generator that adjustably provides a neutral zone to help an operator find and hold a neutral position, a turn-signal conditioner that provides easier control of turns including elimination of “fishtailing,” tremor control for those with body tremors, adjustable tilt-axis sensitivity to selectively match the motor skills of the user, and overrange shutdown as a safety feature.
In the same patent, Lautzenhiser et al. teach control of a second device, such as a computer and its cursor, both of which may utilize voice-recognition technology to provide the required switching functions.
Even with the great strides that have been provided by head and other body-component control of both speed and turns of power wheelchairs, much still needs to be accomplished. Many still are unable to control their own safety except by the use of a call button. Many are unable to control their own comfort and productivity needs, such as adjusting leg supports, head supports, backrests, heating, cooling, and lighting. And many are unable to control productivity devices, such as computers, and entertainment devices, such as radio or television.
In the industry, apparatus for controlling safety, productivity, comfort, and entertainment devices have been called “Environmental Control Units” (ECU). Therefore, this terminology is used extensively in the detailed description.
Furthermore, there are many individuals whose condition has left them unable to operate a power wheelchair using normal control methods. These individuals may have very limited control over their head and other body-member. For these individuals, using their head or single body-member to control both X and Y movement may be difficult or impossible. What is needed is a control method to enable individuals with extremely limited physical ability to control a power wheelchair or ECU using only a single range of motion in their head or other body-member.
The present invention includes rate-of-change control devices, timed-opportunity switches, and multiplexers.
More particularly, the present invention provides rate-of-change control devices that actuate in response to adjustable rate-of-change thresholds, timed-opportunity switches that can be actuated by one or more appropriately-timed inputs, and multiplexers, that can be used by physically-handicapped persons to control such things as wheelchair and hospital bed positioning actuators, lighting, entertainment, communication, computer and productivity devices.
The timed-opportunity switches and the multiplexers can be actuated by any type of momentary-contact switch. However, preferably, the rate-of-change control devices of the present invention are used in combination with mechanical-to-electrical transducers.
With regard to the rate-of-change control devices, repeated ones of output signals, from transducers such as X-Y tilt sensors, are differentiated with respect to time, and then discriminated to provide rate-of-change switching functions that can be used to control start-up (power on) of power wheelchairs, to control additional external devices, and/or to provide a safety shutdown for power wheelchairs. Additionally, the rate-of-change control devices may be used to control wheelchair and hospital bed positioning actuators, lighting, entertainment, communication, computer and productivity devices
If an input position of a mechanical-to-electrical transducer is “y,” then the output is equal to f(y). Thus, it is equally accurate to speak of differentiating the input or the output, although from a practical standpoint, the electrical output is differentiated.
While highly successful results have been achieved by differentiating only once, thereby producing values that are a function of the velocity of the input “y,” alternately, the electrical outputs are differentiated twice, thereby providing values that are a function of the acceleration of the input “y.”
The rate-of-change control devices have two basic advantages. One is that they can use the output of transducers, such as head-attached X-Y tilt sensors that are used to control speed and steering of wheelchairs, to provide switching functions. An other advantage is that the rate-of-change control devices are self-centering, or self-nulling. That is, they function by differentiating an output, and the differential of a constant is zero. Therefore, when an output of a transducer is constant, the rate-of-change control device does not produce an output.
By differentiating signals generated by a two-axis transducer, such as an X-Y tilt sensor, two rate-of-change signals are produced for each axis, one for an increase in the output signal, and one for a decrease in the output signal.
Preferably, the rate-of-change control device that is used with the timed-opportunity switch and the signal conditioner that is shown herein, produces a single switching output from the four rate-of-change signals.
That is, switching occurs when any one of four rates-of-change is beyond a preselected threshold. For instance, when used with a head-attached X-Y input device, a nod of the head can be used to produce a logic “1” output, and returning the head to a level position can be used to produce a second logic “1” output.
In a simplified embodiment of the rate-of-change control devices that are included herein, two rate-of-change switching outputs are produced in response to outputs from a single-axis transducer. One rate-of-change output is produced whenever the rate-of-change of an increasing output exceeds a predetermined magnitude. And, the other rate-of-change output is provided whenever the rate-of-change of a decreasing output exceeds a predetermined magnitude. However, this embodiment can be simplified further by eliminating one comparator. Then, only one output will be produced.
In a slightly more complex embodiment of the rate-of-change control devices, two rate-of-change switching outputs are produced from a single-axis transducer, the two rate-of-change outputs are combined to produce a single switching output, and the single switching output is used to control a relay.
In other embodiments of the rate-of-change control devices, switching outputs are produced that are combinations of one or more sequential rate-of-change signals. For instance, an “1” output can be made to equal A AND B, by holding A until B occurs, or visa versa.
Or a logic “1” can be made to equal “A AND A,” where “A AND A” refers to two “A” signals that are sequential, and the first “A” signal is held until the second “A” signal occurs.
Therefore, although only four logic “1” signals are available from a two-axis transducer, by using digital logic, a large number of logic outputs can be produced.
One of the rate-of-change control devices, or any momentary-contact switch, may be used to initiate the timed-opportunity switch. If a switched signal is provided within a first window-of-opportunity, power is supplied to a first apparatus, such as an electrically-propelled wheelchair. Or, if a switched signal is provided within a second window-of-opportunity, the environmental control unit becomes controllable by the rate-of-change control device, or any momentary-contact switch.
In an other application of the rate-of-change control devices, a rate-of-change signal exceeding a preset threshold will shut down the electrically-propelled wheelchair. This signal will occur in such instances as an X-Y transducer being knocked off of the head of a user, if some force jars the head of the user, and even if the cord from the X-Y transducer is given a sudden jerk.
It is important to remember that a constant value, differentiated as a function of time, is zero. Therefore, no matter what constant output a transducer may produce when it is at null, or is not being actuated, dy/dt is zero.
Therefore, while rate-of-change control devices have been shown and described in conjunction with proportional-output transducers that are used to control apparatus, such as a power wheelchair, the rate-of-change control devices of the present invention may be used with any transducer that will produce a change in output in response to an input.
Further, since the neutral position of a transducer, that is used with the rate-of-change control device, is whatever input position the transducer has immediately preceding a rate-of-change that is of sufficient magnitude to cause switching, there is no requirement that the transducer have a neutral position, that its output be even relatively repeatable, that its output be even relatively free of drift, or that it be even relatively free of hysteresis.
In another embodiment of the invention, motion control is provided through one or more switches. The switches can be any combination of switches including infrared, magnetic, mechanical, optical, proximity, ultrasonic or any type of switches capable of providing an open/closed output. A device, such as a powered wheelchair, may be operated optimally by 4 switches configured to provide motion control or alternatively by 3, 2 or 1 switch(es) similarly configured. Full control using fewer than four switches is enabled through the use of a set of one or more flip-flop circuits that allow the input from one or more of the switches to step through a series of control means.
As defined herein, a rate-of-change control device includes a differentiator and whatever additional components may be required to perform the desired switching functions in response to an input received from a transducer. When a transducer is included with the rate-of-change control device, the combination is a rate-of-change switch.
In a first embodiment, the invention provides a method which comprises: actuating a switch; disabling control of a device in response to the actuation of the switch; selectively actuating a transducer; generating a control signal in response to the actuation of the transducer; storing a voltage offset proportional to the control signal generated by the actuation of the transducer; enabling control of the device; selectively increasing or decreasing the voltage of the control signal; and operating the device using the control signal from the transducer wherein the signal is modified by the voltage offset.
In a second embodiment, the invention provides an apparatus comprising: means, comprising first and second transducers that are connected to a powered wheelchair, for moving said powered wheelchair in X and Y direction in response to body member actuating said transducers; means for conditioning a control signal generated by the selective actuating of said transducers; means for storing and applying a voltage offset to the control signal; means for selecting control of either an external device or the powered wheelchair; and means for selectively increasing or decreasing the voltage of the control signal to enable operation one of a set of unique powered wheelchairs.
In a third embodiment, the invention provides a method which comprises: actuating a switch; powering on a device in response to said actuation; if a specified number of input switches are connected to the device, operating the device in a first mode of operation by selectively operating at least one control switch connected to the device wherein the operation of the at least one control switch generates a control signal; if fewer than the specified number of input switches are connected to the device, selecting a second mode of operation in response to a unique operation of the at least one control switch connected to the device; selectively increasing or decreasing the voltage of the control signal; and operating the device in the second mode of operation by selectively operating the at least one control switch connected to the device. The switch used in this method may be either an active or a passive switch.
In a fourth embodiment, the invention provides an apparatus comprising: means, comprising at least one active or passive switch that are connected to a powered wheelchair, for moving said powered wheelchair in X and Y direction in response to body member actuating said at least one active or passive switch; means, comprising at least one active or passive switch, for alternating control of the powered wheelchair between positive X, negative X, positive Y, and negative Y directions in response to body member actuating said at least one active or passive switch; means for conditioning a control signal generated by the selective actuating of said at least one active or passive switch; means for selecting control of either an external device or the powered wheelchair; and means for selectively increasing or decreasing the voltage of the control signal to enable operation one of a set of unique powered wheelchairs.
In order to facilitate a full understanding of the present invention, reference is now made to the accompanying drawings, in which like elements are referenced with like numerals. These drawings should not be construed as limiting the present invention, but are intended to be exemplary and for reference.
The present invention will now be described in more detail with reference to exemplary embodiments as shown in the accompanying drawings. While the present invention is described herein with reference to the exemplary embodiments, it should be understood that the present invention is not limited to such exemplary embodiments. Those possessing ordinary skill in the art and having access to the teachings herein will recognize additional implementations, modifications, and embodiments, as well as other applications for use of the invention, which are fully contemplated herein as within the scope of the present invention as disclosed and claimed herein, and with respect to which the present invention could be of significant utility.
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The system 1000 is powered on using power control 1300. When the system 1000 is powered on using power control 1300, the latch and delay controller 1350 is also activated. When the latch and delay controller 1350 is activated, the input voltage into the system 1000 is held at a neutral voltage until the input from the transducer 1050a is determined to be centered or within a determined null width. More specifically, a resistor biases the circuit high and switches between buffer 1770a and buffer/splitter 1425a is closed. The voltage downstream from the switch is held at a neutral signal voltage of 5 volts. Upstream from the switch a capacitor, in this embodiment a 6.8 μF 100 volt ceramic capacitor, stores an offset voltage from the tilt transducer 1050a's input signal voltage. When the delay in the latch and delay controller 1350 times out it pulls the voltage on the circuit low, opening the switch between buffer 1770a and buffer/splitter 1425a, and buffer/splitter 1425a begins to receive the voltage signals from the transducer 1050a that are offset by the voltage offset stored in the capacitor. Alternatively, an activator/detector module may be attached to a BNC connection port between buffer 1770a and buffer/splitter 1425a. The activator/detector module detects any reclining or tilting of the seat of a powered wheelchair device. If the seat is reclined or tilted by the user, a switch is closed causing a neutral voltage of 5 volts to be sent downstream, halting user control. A new voltage offset is stored in a capacitor, and when the switch is opened the new voltage offset is applied to the input signal voltage from tilt transducer 1050a.
Before being routed by buffer/splitter 1425a the signal is processed by both the over-range limiter 1200 and over-rate limiter 1250. The function of the over-range limiter 1200 is to halt signal input if the input signal is over a predetermined limit. The over-range limiter 1200 will send a signal to the lockout circuit 1650 if the input signal from either of the tilt transducers 1050a or 1050b is over an acceptable input range. The signal from the over-range limiter 1200 to the lockout circuit 1650 will be sent until the signal from the tilt transducers is back within the acceptable input range. The function of the over-rate limiter 1250 is to filter out unwanted or unsafe acceleration signals from either the X or Y input. The over-rate limiter 1250 will send a signal to the lockout circuit 1650 if rate of change in the input signal from the tilt transducers 1050a or 1050b is over an acceptable limit.
The voltage signal from the buffer/splitter 1425a is limited by the signal limiter 1400a and 1450a. If an external device is connected to the system 1000, real time, unbuffered, input can be sent to the USP connected external device through real-time input circuit 1600a. The voltage signal is simultaneously processed by the buffer 1760a and null width generator 1525a.
The null width generator 1525a receives a null width voltage from null width adjustment circuit 1500. The null width voltage is used to specify a null width or “dead zone” wherein any voltage signal from the tilt transducer 1050a will be interpreted as “null” or neutral. The null width adjustment circuit 1500 can be used to adjust the upper and lower limits of the null width voltage to be used in comparisons by the null width generator 1525a. The null width generator 1525a compares the signals from the buffer/splitter 1425a, which has been limited by signal limiters 1400a and 1450a, to the null voltage provided by the null width adjustment circuit 1500. If the voltage signal is within the null voltage range, the null voltage generator 1525a will supply a null or neutral voltage signal, effectively ignoring the original voltage signal. If the voltage signal exceeds the limits of the null voltage the voltage signal will be further conditioned by the signal conditioner 1950a. The null width generator 1525a may also be adapted to send a signal to a display device to provide a visual indication that the tilt transducer 1050a is in a centered or neutral position.
The attack/decay conditioner 1575a provides for a rapid decay and return to neutral of the signal voltage when the tilt transducer 1050a begins to return to a centered position. This feature prevents over-steering and provides for rapid braking or deceleration.
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The voltage signal is then further buffered by buffer 1750a before being checked by watch dog circuit 1800. The watch dog circuit 1800 functions as a system safeguard. If any circuits or modules upstream of the watch dog circuit 1800 malfunction, the watch dog circuit 1800 will determine that the voltage signal at the watch dog circuit is in an error state. If the voltage signal is in an error state, the watch dog circuit 1800 will send a signal to the emergency stop circuit 1675, which will then activate the lockout circuit 1650a. If the emergency stop circuit 1675 is activated by the watch dog circuit 1800 or through any other means, the entire system 1000 must be powered off and on to reset the emergency stop circuit 1675.
If the lockout circuit 1650a has not been activated and the voltage signal is not in an error state as determined by the watch dog circuit 1800, the voltage signal is further conditioned by the X/Y proportioner 1850. The X/Y proportioner 1850 compares the voltage signals from the transducers 1050a and 1050b representing control of the Y and X axes respectively. The purpose of the X/Y proportioner is to keep the device controlled by the system 1000 from performing undesirable turning or acceleration maneuvers. For example, if the signal voltage for control of the Y axis is in a high positive state for a high rate of forward motion, the X/Y proportioner 1850 will condition the signals for the Y signal voltage to prevent the signal voltage for the Y axis from also being in a high positive state. The Y input signal is conditioned non-linearly as a function of the X input signal, and the X input signal is not changed or reduced. This proportional conditioning prevents a device controlled by the system 1000 from “fishtailing” or performing other undesirable or unsafe actions.
A final voltage offset is applied to the signal voltage by the final offset and Z-axis circuit 1900. The offset to be applied is selectable by the user. The voltage offset allows the control system 1000 to be used with a variety of different devices to enable compatibility with a variety of different devices. The voltage offset and Z-axis circuit 1900 can also be used to supply a reference voltage signal for a “Z-axis” to be used with certain devices.
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Operation of the control system 2000 is enabled when the user operates a switch connected to the active/standby port on switch control 2100. When this switch is operated, a signal is sent to the active/standby circuit 2400. When the signal is received at the active/standby circuit 2400, flip-flop circuits 2200, 2250, 2300, and 2350 are reset to their starting state, and user control of the control system 2000 is enabled. However, no reset is performed if the flip flop circuits are in their default state.
The user may connect one or more switches to switch control 2100 to enable control of a device connected to the control system 2000. For motion control, a maximum of four (4) switches can be used. This can be any combination of switches including mechanical, proximity, ultrasonic, infrared, or any type of switches capable of providing an open/closed output. By selecting multiple switch ports, the control system 2000 can be operated with 3, 2, or 1 switch(es) for motion or device control in the event of a progressive illness such as ALS. The switch connectors, switch jacks and/or switch ports will accommodate and interface with both passive switches such as an Able Net Jelly Bean Twist 10033400, and active switches such as an Omron capacitive proximity sensor requiring a source of power such as E2K-F10MC1. If three or fewer switches are used, one or more of the input switches used for motion control are used to control motion in more than one direction. For example, a flip-flop circuit may be used to allow a single switch to step through the control outputs, and the resulting movement of the power wheelchair would step through forward and reverse and/or left and right motion control. Any combination of input switches may be used and the input switches may be placed anywhere on the user's body or wheelchair where the user has adequate body or body member control to operate the switches.
In a two switch configuration for the Y axis, a first switch allows the user to control the +Y axis, and a second switch allows the user to control the −Y axis. If the first switch is operated by the user, a signal is sent from the switch control 2100 to Y-axis common control circuit 2600 for +Y axis control. In this state, input from the switch will be conditioned to provide +Y axis control. If the second switch is operated by the user, a signal is sent from the switch control 2100 to Y-axis common control circuit 2600 for −Y axis control. In this state, input from the second switch conditioned to provide only −Y axis control.
In a single switch configuration for the Y axis, a switch allows the user to control either the + or −Y axis control by stepping through both control methods. In the default, or starting state, Y+/− flip-flop circuit 2300 provides for user control of the +Y axis. If the user operates the switch, a signal is sent from switch control 2100 to the Y+/− flip-flop circuit 2300 which switches to enable user control of the −Y axis. The next operation of the switch will return the Y+/− flip-flop circuit 2300 to the default state, providing user control of the +Y axis.
User selection of X axis control is performed in a similar manner to Y axis control. The user may connect one or two switches to provide the user with + and −X axis control. In a two switch configuration for the X axis, a first switch allows the user to operate +X axis control, and a second switch allows the user to operate −X axis control. If the first switch is operated by the user, a signal is sent from the switch control 2100 to X-axis common control circuit 2650 for +X axis control. In this state, input from the first switch will be conditioned to provide +X axis control. If the second switch is operated by the user, a signal is sent from the switch control 2100 to X-axis common control circuit 2650 for −X axis control. In this state, input from the second switch conditioned to provide −X axis control.
In a single switch configuration for the X axis, a switch allows the user to operate either + or −X axis control by stepping through both control methods. In the default, or starting state, X+/− flip-flop circuit 2350 provides for user control of the +X axis. If the user operates the switch, a signal is sent from switch control 2100 to the X+/− flip-flop circuit 2350 which switches to enable user control of the −X axis. The next operation of the switch will return the X+/− flip-flop circuit 2350 to the default state, providing user control of the +X axis.
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Additional switches may be connected to switch control 2100 to enable additional features of the control system 2000. A switch may be connected to switch control 2100 to enable control of the Y lo/hi flip-flop circuit 2250. Operation of a switch connected to the Y lo/hi flip-flop circuit 2350 will enable the user the input higher values for the +Y control signal. In normal operation, the absolute value of the Y axis voltage signal is limited to a certain value. A user may wish to increase the limit to enable, for example, faster movement of a powered wheelchair when outdoors. If the switch connected to the Y lo/hi circuit 2250 is operated, the Y lo/hi circuit 2250 switches to the higher Y signal voltage limit value. A second operation of the switch will return the limit to the original, lower value, and additional operation of the switch will step through the signal voltage limits as described above.
A switch may also be connected to switch control 2100 to enable control of an external device connected to USP control 2700. Operation of a switch connected to USP control 2700 will provides the user with the ability to select between control of a powered wheelchair device and an external device connected to the control system 2000. A switch may also be connected to switch control 2100 to enable an emergency stop feature. If a switch for an emergency stop feature is operated, lock-out circuit 2800 supplies the device connected to control system 2000 with a neutral voltage, disabling user control until the control system is powered off and on.
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A further control system 2000 safety feature is the rapid deceleration inhibitor 2750. The rapid deceleration inhibitor 2750 prevents rapid deceleration via a rapid drop in signal from the +/−X or Y signal voltages due to the user operating a switch connected to switch control 2100. This feature prevents, for example, rapid braking or overly sharp turning due to the user switching from forward to reverse control, or from forward to left control, by operating a switch connected to switch control 2100 while the voltage signal from an input switch is at a high absolute value. The rapid deceleration inhibitor 2750 is engaged whenever any control switch, e.g., forward, forward plus, forward/reverse, or reverse in Y-axis common control 2600, is operated. When a control switch is operated, a switch in the Y-axis common control 2600 is opened, removing the resistor that enables a rapid bleed-off of the signal voltage out of the circuit. When a control switch is no longer operated, the switch is closed and the resistor is reconnected to the circuit, enabling a rapid bleed-off of the input signal voltage. In the Y-axis common control 2600 this prevents jerky motion and unwanted rapid deceleration.
A final voltage offset is applied to the signal voltage by the final offset circuit 2900. The offset to be applied is selectable by the user. The voltage offset allows the control system 2000 to be used with a variety of different devices. The voltage offset circuit 2900 can also be used to supply a reference voltage signal for a “Z-axis” necessary for the operation of certain devices.
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While specific apparatus and method have been disclosed in the preceding description, it should be understood that these specifics have been given for the purpose of disclosing the principles of the present invention and that many variations thereof will become apparent to those who are versed in the art. Therefore, the scope of the present invention is to be determined by the appended claims and their respective recitations.
The present application claims benefit of priority to and is a continuation of U.S. Provisional Pat. Application Ser. No. 61/770,904, filed Feb. 28, 2013, and entitled METHOD AND SYSTEM FOR CONTROL OF APPARATUS (Lautzenhiser), which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | |
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61770904 | Feb 2013 | US |