Patent Application
20050080518
The present invention is directed to the field of power driven wheelchairs, in general, and more particularly to an integral joystick display therefor and a method of operating the same.
Power driven wheelchairs which may be of the type manufactured by Invacare Corporation of Elyria, Ohio, for example, generally include right and left side drive wheels driven by a motor controller via respectively corresponding right and left side drive motors, all of which being disposed on the wheelchair. An exemplary illustration of such a motor drive arrangement is shown in the schematic of
A user interface 16 Which may include a joystick 18 and selection switches (not shown) operable by a user is also disposed on the Wheelchair in a convenient location to the user. The user interface 16 is generally interfaced to the microcontroller 15 over a two wire serial coupling 20 to permit the user to select a drive program appropriate for operating the wheelchair in its environment and to adjust the direction and speed of the wheelchair within the selected drive program. In the present example, a main program of the microcontroller 15 which may contain the plurality of drive programs is stored in a non-volatile memory 19, like a read only memory (ROM), for example, -which may be integrated into the microcontroller 15 or may be a separate component thereof.
The motor controller 10 is generally powered by a battery source 22, which may be 24 volts, for example, also disposed on the wheelchair. The drive motors 12 and 14 may be of the permanent magnet type and may be either a gearless, brushless AC motor or a brush type DC motor. The microcontroller 15 is interfaced and responsive to the user interface 16 to control drive signals 24 and 26 to motors 12 and 14, respectively, via a power switching arrangement configured in accordance with the motor type being driven. The power switching arrangement may be powered by the 24V battery 22. Thus, as the user adjusts the speed and direction of the wheelchair via the joystick of interface 16, appropriate drive signals 24 and 26 are controlled by motor controller 10 via microcontroller 15 to drive the motors 12 and 14 accordingly.
Motor controller 10 generally controls motor speed to the user setting utilizing a closed loop controller programmed in the microcontroller 15. Actual speed of each motor 12 and 14 may be derived from signals 28 and 30 respectively sensed therefrom. For example, for AC motors, a Hall Effect sensor may be disposed at the motor for sensing and generating a signal representative of angular position. The signals 28 and 30 are coupled to the microcontroller 15 which may be programmed to derive motor speed from a change in angular position for use as the actual speed feedback signal for the closed loop speed control of the motor. For DC motors, the voltage Va across the armature and armature current Ia may be sensed from each motor 12 and 14 and provided to the microcontroller 15 via lines 28 and 30, respectively. Microcontroller 15 may under programmed control derive the actual speed of each motor 12 and 14 from the respective voltage Va and current Ia measurements thereof for use as the speed feedback signal for the respective closed loop speed control of each motor 12 and 14.
In addition, interaction with the motor controller 10 is performed through a remote programmer 34 which may be electrically coupled to a port of the microcontroller 15-via signal lines 36, for example. Each remote programmer 34 may include a screen 38 for displaying interactive text and graphics and a plurality of pushbuttons 40 for communicating with the microcontroller 15 which is programmed to interact with the programmer 34. A dealer is generally provided with one or more remote programmers for rendering the wheelchair unique to the user's safe operating capabilities.
Present joystick interface units 16, like the joystick unit interfaced to Invacre's MK IV controller, for example, do not have an interactive display, but rather are only capable of displaying an indication of battery discharge which may be a line bar representative of the charge remaining on the battery 22, for example. It is desirable from both a user and dealer standpoint to have a display which may selectively display screen images of current operational parameters of the wheelchair. Display of such operational parameters of the wheelchair will enhance the ability to know when to replace and service certain components of the wheelchair.
The present invention provides such a display integral to a joystick unit which is already interfaceable to and operable with the microcontroller 15 for hands-on control to render a more convenient and less costly add-on display.
In accordance with one aspect of the present invention, apparatus of a power driven wheelchair for displaying operational parameters thereof comprises: a programmed controller operative to monitor a plurality of operational parameters of the wheelchair; a joystick unit coupled to the programmed controller; and a display screen integral to the joystick unit, wherein the programmed controller being operative to interact with the joystick unit to display a user selected operational parameter of the plurality on the display screen of the joystick unit.
In accordance with another aspect of the present invention, a method of displaying operational parameters of a power driven wheelchair on a display screen integral to a joystick unit of the wheelchair comprises the steps of: monitoring a plurality of operational parameters of the wheelchair by a programmed controller; coupling the joystick unit to the programmed controller; utilizing the joystick unit to select an operational parameter of the plurality; and operating the programmed controller to interact with the joystick unit to display the selected operational parameter of the plurality on the display screen of the joystick unit.
The microcontroller 15 further responds to movement of a drive select momentary switch 58 via signals over the cable 20 to control the wheelchair in a drive program selected by the user. The unit 50 additionally includes a one-eighth inch diameter phono plug or jack 60 located at the rear of the unit. In the present embodiment, a momentary switch 62, which may be an ability switch, for example, may be plugged into the jack 60 such that when the contacts of switch 62 are closed a representative signal is conducted over the cable 20 to the microcontroller 15. Usually, an ability switch includes a flexible stem and an integral switch which is normally open. Moreover, a bending of the flexible stem momentarily closes the integral switch thereof.
A block diagram schematic of an exemplary joystick unit 50 suitable for use in the embodiment of
An external analog to digital converter (A/D) 306 may be used to read and digitize voltage signals from the joystick 56 and rotary knob 54 of the unit 50. The digitized signals are received by the microcontroller 300 which transmits them serially over cable 20. Also, input/output (I/O) circuits 308 of the microcontroller 300 are coupled to the switches 58 and 62 for reading the states thereof which may be also transmitted serially over cable 20 by the microcontroller 300. Additional I/O circuits 310 of the microcontroller 300 are coupled to the LCD 52 which is controlled by address (A), data (D), and control (C) lines of the microcontroller 300. At times, data may be temporarily stored in a scratch pad or random access memory (RAM) 312 of the microcontroller 300. Serial protocols, such as CAN and RS232, for example, may be used by the microcontroller 300 for serial communication.
In the present embodiment, the LCD 52 may be of the type manufactured by Hantronix under the part no. HDM12216L, for example. As will become more evident from the following description, all of the data that appears on the display 52 is determined by the microcontroller 15 and transmitted to the joystick unit 50 over cable 20. In the unit 50, the microcontroller 300 receives and translates the serial data from cable 20 and delivers the data directly to the LCD 52 for display in an appropriate screen image format. In the alternative, the microcontroller 300 may receive data from the microcontroller 15 via serial lines 20, process and/or store it in the RAM 312, then transfer it to the LCD 52 for display.
Returning to
Still further, a battery circuit 68, which may be part of the motor controller 10, for example, may be connected to the battery 22 for monitoring certain operational parameters thereof, like voltage and current, for example. In the present embodiment, circuit 22 may generate signals representative of the current battery voltage and battery current being used, and provide such signals to the AID unit 64 wherein such signals may be sampled and digitized. The sampled, digitized voltage and current data of the battery 22 may be stored in memory 66. The microcontroller 15 is also programmed to derive from the battery voltage and current data trip battery consumption or battery capacity consumed since the wheelchair was last powered on in parametric units of amp-hours (AH). The derived and measured values may be stored in designated registers of memory 66.
Further yet, the battery circuit 68 may be controlled by the microcontroller 15 to perform a load test on the battery 22 from time to time and measure the current battery condition (BATT) based on each load test. In the present embodiment, the battery load test is performed automatically and without user intervention. For example, the microcontroller 15 may execute a routine which monitors the battery voltage, time and current load on the battery. During the routine, when the right sequence of events occurs during normal usage of the wheelchair, the load test data is captured and the display is updated as will become more evident from the description below. Factors in the sequence are: battery fully charged, a five minute rest period before the load test, a load on the batteries of 30-40 amperes, and the load is stable long enough for the data to be considered valid.
A voltage difference or drop between the rest battery voltage and the loaded battery voltage is read by the microcontroller 15 via A/D 64 and stored in a non-volatile portion of the memory 66, which may be EEPROM, for example. In the present battery load test routine, if the voltage drop under load is in the approximate range of 0-2.0V, the battery or batteries are considered good. If the voltage drop under load is in the range of 2-2.5V, the battery is considered poor, and if the voltage drop is more that 2.5V, the battery is considered bad. The resulting measured battery status of “GOOD”, “POOR” or “BAD” is stored in memory 66 for display when selected as will become better understood from the following description.
In accordance with the present invention, certain operational parameters of the wheelchair, like current speed (speedometer), trip miles or kilometers (trip odometer), total distance in miles or kilometers (odometer), battery capacity consumed since the chair was last powered on (trip amp-hour meter), current battery voltage (battery volts), battery current being used (battery amps), and load test results (good, poor or bad), for example, may be selectively displayed on the integral joystick display 52 via communication over the serial communication cable 20.
An exemplary screen image displayed by the microcontroller 15 on the LCD 52 via microcontroller 300 of unit 50 is shown in
To accomplish the foregoing described left side image screen display, the microcontroller 15 is pre-programmed to function in accordance with the following steps. The microcontroller 15 determines the drive program selected by the switch 58 of the joystick unit 50 and stored in memory 66, and sends serial data over cable 20 to render the selected drive program displayed on the top line of the left side screen image section 80 as shown in
On the right side section 82 of the exemplary screen image of
The selection between English and metric units may be made with the programmer 34 described in connection with the embodiment of
A benefit of integrating the display 52 in the joystick unit 50 is to allow the user to interact via the microcontroller 15 with the display 52 through movement of the joystick 56 and/or other switches on the unit 50, for example. One of the user interactions is the selection of the operational parameter to be displayed as will become more evident from the following description. Thus, the microcontroller 15 is programmed to detect a command to enter a display select mode which is transmitted over cable 20 from the microcontroller 300 of joystick unit 50 to the microcontroller 15. While in such mode, the microcontroller 15 is further programmed to detect commands transmitted over cable 20 from the microcontroller 300 of unit 50 to determine the operational parameter selected by the user for display in the information center 82. And, in response, the microcontroller 15 is operative to send the associated operational parameter data serially over cable 20 to the microcontroller 300 of joystick unit 50 to render the units and value of the selected parameter displayed on the top and bottom lines of the information center 82 of the screen image as described above.
An exemplary program suitable for use in the microcontroller 15 for interacting with the joystick unit 50 and display 52 is shown in the flowchart of
When the display select mode is entered as determined by block 100, decision block 102 determines if the joystick 56 is moved to a predetermined position, like to the left, for example. In the present embodiment, the microcontroller 300 of unit 50 detects a joystick movement to the left and sends a command to the microcontroller 15 over cable 20, which command being identified by block 102. If no command is present after a predetermined time period as determined by decision block 104, then execution is returned to block 100 awaiting for the next command for entry into the display select mode. Otherwise, program execution continues at block 106 wherein data of the parametric units and value of an operational parameter next in a predetermined sequence is provided to the microcontroller 300 of unit 50 over cable 20 for display in the screen image of the display 52. For example, if speed of the wheelchair is the next parameter in the predetermined sequence, then the screen image exhibited in
If in block 102, it is identified that the joystick 56 remains in the left position, then data of the operational parameter next in sequence is again provided to the microcontroller 300 of unit 50 for display in the information center of display 52. If the next parameter is trip odometer, then the screen image will appear as shown in
While the present invention has been described herein above in connection with one or more embodiments, it is understood that such description is presented by way of example with no intent of limiting the invention in any way. Rather, the invention should be construed in breadth and broad scope in accordance with the recitation of the claims appended hereto.
