Abstract: An electronic control system for a stair climbing vehicle, such as a wheelchair is disclosed. Front and back sensors are provided for detecting a stairway or slope. The electronic control system determines from the sensor data whether the slope has an acceptable incline for traversing. If it is not acceptable, the vehicle will be prevented from entering onto the stairway or slope. A seat for a user is tilted in accordance with electronic controls to keep the user approximately vertical with respect to gravity as the vehicle traverses the stairs. The allowed operation of the vehicle is controlled via parameters which can be changed by removable memory which configures the vehicle for a particular user or group of users.

Abstract: The present invention provides a sensor for detecting the angle of an incline, such as a staircase, before it is reached by the wheelchair. A control signal is provided to a motor for tilting the seat to cause the seat to be tilted to a predetermined minimum safe angle before the wheelchair reaches the staircase. The minimum safe angle is an angle of tilt at which the wheelchair will not roll over if the tilting mechanism should fail to completely rotate the seat to a horizontal position and as the stairs are descended. The minimum safe angle is determined by the position of the center of gravity of the wheelchair which is affected by the users weight. If the seat does not achieve this minimum tilt, the wheelchair is prevented from going over the stairs.

Abstract: A motorized personal transport vehicle (PTV) with a removable, programmable memory which contains both a key code to enable only an authorized user to operate the PTV and contains constants for use in an algorithm which operates the PTV in accordance with a prescription for that particular user's needs. Control signals from an input, such as a joystick, are modified by the algorithm in accordance with the prescription for a particular user. This prescription is stored in the programmable memory and loaded into the computer when the memory is inserted. The key code in the memory can allow various levels of access, with access for a particular user, a particular group, physician access and technician access. In a preferred embodiment, an electrically erasable programamble read only memory (EEPROM) is used as the memory key.

Abstract: A latch for each of a pair of cushioning arms, respectively, of a stair-climbing wheelchiar. The latch for each arm includes a first member coupled to the arm and a second member coupled to a fixed support of the wheelchair, with the second member being coupled to the armature of a solenoid which is energized to unlatch the arm from latched relationship with the support when it is desired to use the arm for cushioning purposes. An ultrasonic transducer coupled to the wheelchair adjacent to each latch, respectively, provides signals to energize the respecting latch solenoid when the arm is to be unlatched. To latch each arm, the adjacent edge margins of the two members are bevelled so that, during upward movement of the arm, such as by movement of the wheelchair from an inclined position to a horizontal position, the members are spread apart and a first spring biases the two members back together in coupled relationship to each other.

Abstract: A stair-climbing wheelchair having a sensor at the front end thereof for sensing the presence of a stair step or an inclined ramp. The sensor emits signals which reflect from a surface and to a receptor in the sensor, the receptor being coupled to a microprocessor which determines not only the linear distance traveled by the wheelchair in a forward direction, but also the height of a stair step. Thus, when the tracks are down, a microprocessor associated with the sensor will shut off the drive motors to the tracks if the slope of the stairway is too great when the tracks are down. In such a case, the wheelchair backs away from the stairway and does not go down it. If the slope is less than a predetermined value, such as 30.degree.-35.degree., the wheelchair can move down the stairway in the normal fashion.

Abstract: A stair-climbing wheelchair having wheels defining a first wheel base and a pair of endless, flexible tracks providing a second wheel base, there being a motor-driven structure for moving the tracks into and out of ground-engaging positions. A first pivotal arm is pivotally mounted on the wheelchair near the front end thereof. The first arm is coupled to a fluid piston and cylinder assembly which actuates and cushions the pivotal movement of the arm as the wheelchair moves from a horizontal position to an inclined position, such as moving from the top of a stairway to the slope of the stairway as the wheelchair moves down the stairway. Similarly, a second arm coupled with a fluid piston and cylinder assembly is coupled to the wheelchair to cushion the movement of the wheelchair and its occupant as they move from an inclined position to a generally horizontal position, such as at the top of a stairway.