1. Field of the Invention
This invention relates to the field of systems for the operation of motor vehicles with specialized control systems. More particularly, this invention relates to systems whereby the steering, acceleration and braking functions of a conventional motor vehicle are controlled by a single device through the mediation of microprocessors.
2. Description of the Prior Art
The mobility of the individual is considered an essential element in the educational, business and recreational aspects of life in our society. In particular, this mobility permits the individual to be self-sufficient and, therefore, less reliant upon society for his or her well-being. The principal basis for the realization of this individual mobility, which has essentially occurred within the last fifty years, has been the proliferation of motor vehicles. Currently it is estimated that there are more than 120 million individually-owned vehicles in this country alone. Typically, these vehicles are produced, en mass, and sold to individuals who use them to travel from home to school, or to work, or to any other location of choice.
For most individuals this mobility is achieved simply by stepping into their production-line automobiles, turning on the engine and driving away. Unfortunately, within our society there are several hundred thousand Americans who are paraplegic or quadriplegic (i.e., suffer from restricted motion and strength in one or more limbs of the body) and who therefore cannot simply step into their autombiles and drive away. For these individuals the production-line automobile does not provide the mobility most take for granted. Since one of our societal goals, as evidenced by recent legislation--see the AMERICANS WITH DISABILITIES ACT OF 1990, enacted July 26, 1990--is to provide all physically-impaired individuals with equal access to all those activities which are available to the population as a whole, there is great pressure to provide equivalent mobility. To this end, several devices have been developed in order to transform production-line vehicles into accessible and useable vehicles for the physically-impaired. Nevertheless, the prior art devices directed to this end suffer from various deficiencies which make them unsuitable. Generally, these devices have problems related to the electronics and to the user/vehicle interfaces which either render the vehicles inoperable, or at least very difficult to operate by the seriously impaired individual. Confronted with such problems, the handicapped individual may minimize his or her use of the vehicle and this, in turn, undercuts the goal of selfsufficiency.
One particular prior art means for control of a vehicle by a physically-impaired individual is the control device of Ahnafield (U.S. Pat. No. 4,722,416). Ahnafield discloses the use of hydraulic cylinders for operating the steering, acceleration and braking of a vehicle. Control of all of the hydraulic cylinders is achieved through the operation of a remote manipulator and the hydraulic pressure used in the cylinders is delivered by the vehicle's own hydraulic pump. The remote manipulator described by Ahnafield comprises a single joystick of the type well known in the field of motorized wheelchairs. Such manipulators provide two axes of motion wherein side-to-side motion is translated into left and right turns, and forward and backward motion are translated into acceleration and braking.
Another type of control device is the one disclosed by Johnson et al. (U.S. Pat. No. 4,476,954). This device also operates by means of a single joystick, similar to the one described by Ahnafield. The joystick controls input to DC motors which are then used to rotate the steering wheel and to depress the accelerator and brake pedals. In particular, the joystick has a range of motion that approximates the range of motion of an airplane joystick. Although the use of such a joystick for controlling a vehicle is of particular interest to the physically-impaired individual, such a range of motion may limit the usage of the Johnson device to those individuals with the dexterity to reach and maintain full extension as the driving situation dictates.
The prior art devices which provide a joystick method of operating a vehicle all fail in one particular aspect: they do not fully address the needs of the physically-impaired individual. Although such individuals have physical deficiencies, they respond to driving stimuli utilizing the same mental processes as fully functional individuals. In order to provide vehicle access to all but the most severely impaired, there must be a control system which translates the limited movement and strength of the individual into commands that direct the vehicle to operate as a function of the mental process rather than the physical process. To do so, the translation from electronic input, initiated by the physically-impaired individual, to operation of the vehicle must be as smooth as the translation from the brain to the hands and feet of the normal individual.
Additionally, to make the vehicle completely adapted for physically-impaired use, there must be means by which the impaired individual may control the vehicle in the event of catastrophic failure of the control system. In the prior art devices, failure of one or more major components disables the control system and prevents the physically-impaired individual from controlling the vehicle entirely. Such catastrophic failures are often caused by environmental exposure of system components placed external to the passenger compartment of the vehicle. It is therefore essential that any backup system be placed within the passenger compartment of the vehicle. Also, any backup system which permits continuous operation by the impaired individual after catastrophic failure of a primary component must continue to account for the similarities in mental processing as described above.
A further problem associated with the prior art devices is the difficulty in switching control of the vehicle from a unitary mode of control to a conventional able-bodied mode of control. These devices often require hours of servicing by an expert mechanic to remove all the disabled-body features and reset the standard steering and acceleration/braking functions.
Therefore, what is needed is a control device for the operation of a vehicle by a physically-impaired individual that: (1) provides a means by which the normal thought processes used in steering, accelerating and braking a vehicle can be implemented smoothly regardless of the physical impairment of the operator; (2) provides multiple redundant backup systems to guard against catastrophic failure of the system; (3) accommodates the full range of impairments associated with the particular individual; (4) is contained within the passenger compartment of the vehicle; and (5) can be easily switched, in a short period of time, from disabled-body control to conventional able-body control.