GB2390065A

GB2390065A - An active level control system for electrically propelled vehicles

Info

Publication number: GB2390065A
Application number: GB0210689A
Authority: GB
Inventors: Simon Griffin
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-05-10
Filing date: 2002-05-10
Publication date: 2003-12-31
Also published as: GB0210689D0

Abstract

An electrically powered wheelchair has a mainframe chassis CH3 that supports the seating, armrests and footrest components, and can be controlled to remain laterally horizontal as the wheelchair traverses across slopes of varying inclination. This is achieved automatically by means of a level sensor device 4 interfacing with an adjustable link 6 which can articulate the mainframe chassis CH3 relative to the rear wheeled chassis CH1. The handicapped user benefits from such a system in that they are not disorientated by a continuous disturbance of posture when driving over unleveled terrain. Also on such terrain an improved level of lateral stability is achieved and consequently an improved level of drive wheel traction.

Description

An Active Level Control System for Electrically Propelled Vehicles

Description

The present invention relates to an active level control system for any electrically propelled vehicle whose maximum speed does not exceed 7mph, and more particularly, the present invention relates to an active level control system for an electrically powered wheelchair Electrically powered wheelchairs for handicapped people are perhaps the most well known of the electrically powered vehicles which comprise of a wheeled chassis upon which are mounted the seating, armrests and footrest components.

lathe forward and reverse drive, steering and braking are usually achieved by controlling independently the drive to each of the two drive wheels, which may be either the front pair or the rear pair of wheels.

For all wheelchairs, even those which have suspension systems, when the main wheeled chassis travels over ground which is not horizontally level, the seating, armrests, and footrest components and hence the occupant, move in unison with the main wheeled chassis. Hence as the wheelchair begins to traverse across a slope, the following three undesirable events occur, and fig 1 helps to illustrate this where fig l(a) shows the wheelchair happily on level ground, fig 1 (b) illustrates a wheelchair traversing across a slope with an Active Level Control system off and fig 1 (c) shows a wheelchair traversing across a slope with the Active Level Control system on.

Three Undesirable Events: 1. The posture of the occupant will be disturbed.

This disturbance in posture can be both

\ disconcerting and undesirable for many handicapped people.

2. The wheelchair tends towards a more unstable position due to the shift of the Centre of Mass relative to the contact points of the wheels to the ground.

3. The weight distribution to the drive wheel uppermost on the slope reduces as the slope increases. This leads eventually to a loss of traction of that wheel. Consequently the ability to steer a straight course or to steer up the slope is lost and a potentially dangerous situation exists.

By using an Active Level Control system, as described herein, and so maintaining the occupant always laterally level to the horizontal, point 1, above ceases to occur whilst points and 3, above are no longer problematic.

According to the present invention there is provided an active level control system for electrically propelled vehicles, whose maximum speed does not exceed 7mph, comprising of a main frame chassis, the purpose of which is to support the seating armrests and footrest components, and which can rotate, independently of a wheeled chassis, about a longitudinal for and aft axis, but where the main frame chassis is adjustably linked to the wheeled chassis so that by means of a level sensor signal or a tilt angle signal, the adjustable link can extend retract or rotate to maintain the main frame chassis, and hence the occupant, laterally horizontally level.

Advantageously the wheeled chassis can be a four wheeled chassis and which may comprise of a rear wheeled chassis and a front wheeled chassis linked together in such a way that they may rotate relative to one another about a for and aft longitudinal axis so as to maintain always four wheel ground contact when on terrain with normally occurring bumps and undulations.

A specific embodiment of the invention will now be described by way of an example with reference to the accompanying drawing in which Fig 2 shows a side and end elevation of an electrically propelled wheelchair.

Fig 2 shows a mainframe chassis CH3 that is constructed in such a way as to support the seating, armrests and footrest components. CH1 in this example can be described as the rear axle to which are connected the drive motors 9 and 10 and the wheels 11.

Whilst CH2 in this example can be described as the front axle to which are connected the front castor wheels 12. At each end of the main spar 5, which forms a part of the main frame chassis CH3, is a hub bearing arrangement 1 and 8 onto which chassis CH1 and CH2 are assembled and can both articulate. Attached and fixed to the main frame CH3 is a level sensing device 4 which in this case indicates when the chassis CH3 deviates away from the horizontal laterally and in which direction.

At this point the front axle CH2 is free to rotate relative to the rear axle CH1, which is a requirement in order that a four-wheel contact with the ground over undulating terrain is always maintained. Whilst the main frame chassis CH3, is allowed to freely rotate quite independently from both the front and rear axles CH2 and CH1, but for an adjustable link 6 which car control the relative movement between the main frame chassis CH3 and the rear axle CH1.

The adjustable link 6 between CH1 and CH3, in this example, is an electronic linear actuator which can extend or retract according to the signal it receives from the level sensing device 4 and in so doing will control and maintain the seating, footrest and hence occupant in a level attitude.

Claims

Claims

An Active Level Control System For Electrically Propelled Vehicles 1.An active level control system for electrically propelled vehicles, whose maximum speed does not exceed 7mph, comprising of a main frame chassis, the purpose of which is to support the seating armrests and footrest components, and which can rotate, independently of a wheeled chassis, about a longitudinal for and aft axis, but where the main frame chassis is adjustably linked to the wheeled chassis so that by means of a level sensor signal or a tilt angle sensor, the adjustable link can extend retract or rotate to maintain the main frame chassis, and hence the Occupant, laterally horizontally level
2.An active level control system for Electrically Propelled Vehicles as in Claim 1, substantially as described hereinbefore and where the wheeled chassis can be a fourwheeled chassis.
3.An active level control system for Electrically Propelled Vehicles as in Claims 1 & 2, substantially as described hereinbefore and where the four wheeled chassis may comprise of a rear wheeled chassis and a front wheeled chassis linked together in such a way that they may rotate relative to one another about a for and aft longitudinal axis so as to maintain always four wheel ground contact.
4 An active level control system for Electrically Propelled Vehicles as in Claims 1, & 3 substantially as described hereinbefore and where the axes of rotation of the three chassis members, namely the mainframe chassis the rear

wheeled chassis and the front wheeled chassis, are parallel and concentric with one another.
5.An active level control system for Electrically Propelled Vehicles as in Claims 1, 2, 3, & 4 substantially as described hereinbefore and where the level sensor device can detect continuously when the main frame chassis deviates laterally away from the horizontal and in which direction and can subsequently cause the adjustable link to extend, retract or rotate in the correct direction until such point when the level sensor device detects the main frame chassis no longer deviates laterally away from the horizontal.
6. An active level control system for Electrically Propelled Vehicles as in Claims 1, 2, 3, & 4, substantially as described hereinbefore and where the level sensor device can measure continuously and precisely the degree of tilt of the linked wheeled chassis and in which direction and subsequently with this data can instruct the adjustable link to be set precisely in a specific position according to and as a function of this data which will as a consequence maintain the main frame chassis laterally horizontal.
7.An active level control system for Electrically Propelled Vehicles as in claims 1, 2, 3, 4, 5 & 6 substantially as described hereinbefore and where the adjustable link is a linear electrically powered actuator.
8. An active level control system for Electrically Propelled Vehicles as in Claims 1, 2, 3, 4, 5r 6 & 7 substantially as described hereinbefore with reference to Fig 1 of 2 and Fig 2 of 2 - the accompanying drawings.