An in-the-wheel suspension system including a drive mechanism for coupling the rotational motion of a wheel rim to the drive shaft of an electric motor and for supporting the wheel rim with respect to the vehicle chassis using one or more springs and dampers. In a hubless version, a spring member supports extend between a frame member attached to the chassis and a bearing member that engages with the rim. In a version used with a wheel hub, the hub is supported by an axle and the spring member supports the axle in movable relation to the frame member. A pivoting support arm that is attached to the axel and pivots about a pivot point attached to the frame member at a location spaced from the wheel axis may be used to support the hub. A Peaucellier linkage may be used to support the axle for movement along a straight line vertical path, the linkage being attached to the frame member at two fixed pivot points. The wheel suspension units perform all the traditional drivetrain functions independently and can be attached to the chassis in a manner that allows for easy removal.

FIELD OF THE INVENTION

This invention relates to vehicle suspension and drive systems.

BACKGROUND OF THE INVENTION

Placing an electric motor on the hub of a motor vehicle results in space savings and better efficiency in power transmission when compared to other motor placements. There are normally significant disadvantages that flow from attaching the motor to the wheel hub. The resulting dramatic increase in unsprung and rotational mass both adversely affect safety and handling. Moreover, the conventional suspension used to support the combined hub and motor assembly uses space very inefficiently.

Because hub-mounted electrical motors add significant unsprung and rotational mass to a suspension, compromising handling and safety, and because motors mounted outside the hub increase the already large requirements of traditional suspensions for space and complicate production, there is a need for an improved suspension and drive mechanism for use with a wheel driven by an electric motor.

SUMMARY OF THE INVENTION

The present invention may be used to advantage to implement a self-contained, single-wheel, electric motor drive and suspension system that can be independently controlled. Such a self-contained “wheel robot” can incorporate every component needed to drive, steer, suspend and lean a car wheel as required in an automobile or other vehicle. Attached to a chassis with a minimal number of connection points, these self-contained wheel robots only require electrical power and driving data to propel a vehicle. The availability of such a self-contained wheel robot can radically simplify car design, especially chassis design and engineering which become much easier, faster and cheaper because the chassis no longer houses components such as the motor, drive shaft and gear box.

Instead of a rigid chassis holding the wheels in place, a central or distributed computing system may be used to coordinate the action of the wheel robots to perform that function. Using position sensor or the like, the computing system can control any number of wheel robots that work together to drive a vehicle or a set of connected vehicles so that each wheel is positioned relative to the others in a desired configuration, such as at the corners of a square where the wheels are typically positioned by a rigid automobile chassis. Using independently controlled and positioned wheel robots, the control system can be designed such that it directs those wheel robots to maintain that square, without the need for a rigid mechanical link to perform that function.

The present invention reduces the unsprung and rotational mass arising from the placement of an electric motor at the wheel hub of a motor vehicle while maintaining the significant space advantages that this motor placement provides.

As contemplated by the invention, the suspension, power transmission and braking components and, optionally, the motor, are mounted inside a hubless wheel so that the motor is not part of the unsprung mass. Alternatively, a hub can be used, as long as above mentioned advantages are maintained.

The wheel-embedded suspension drastically reduces space requirements compared to conventional suspension systems. Unsprung mass and rotational mass are significantly reduced, greatly improving safety and handling.

Forces are attacked where they are generated, allowing for lighter components, more precise suspension control (ride, handling, steering axis, reducing tire wear), and controlling different suspension aspects (camber, castor, toe in, ride height, steering angle, springing, damping) independently from each other. Therefore, steering, acceleration, and deceleration loads can be distributed equally to all wheels of the vehicle, increasing its balance, its limits of adherence to the road and therefore safety.

Independent toe in, castor, and steering control makes the suspension work equally well in the “forward” and “reverse” direction at any speed. The steering axis may be positioned in the center of the tire contact patch or at the linkage point between the suspension and the chassis, or both, permitting the construction of a truly omni directional vehicle.

Attached to the chassis with “legs”, the wheel-embedded suspension combines excellent on-road performance, economy, and speed with off road capabilities.

The suspension mounting points are designed so that changing a wheel/suspension unit is a easy as changing a tire on a typical car, and such suspension units can be produced, stored, and repaired independently form the rest of the vehicle.

The functions performed by the suspension unit may be controlled electronically, further permitting units to be used on different vehicles by electronically adapting these functions according to the vehicle's dimensions, weight, and weight distribution. Placing the suspension, drivetrain and motor inside a (hubless) wheel results in tremendous space savings compared to conventional suspension systems, even when the electric motor is placed inside the hub of the wheel.

Placing the motor placement inside the rim is more energy and space efficient while placing the motor outside the wheel allows maximum suspension travel, allows a larger motor to be used, and creates the opportunity but is not a prerequisite for a second steering axis controlled by a second motor.

By attaching the wheel-embedded suspension to actively movable legs, the behavior of the system may be dynamically controlled to provide improved on-road speed and handling with excellent off-road capability.

In one embodiment, suspension springs and dampers connect a motor mount rigidly attached to the chassis to one or more members that engage with the wheel rim and a belt, chain or other mechanism transmits rotational forces between the wheel rim and the motor. The drive mechanism can take the form of a transmission shaft one or both ends of which engage with a rim gear that slidably engages with a motor gear that engages with the chassis-mounted motor while permitting the drive shaft to move with the wheel.

In other embodiments, the wheel is attached to a support arm that pivots about an axis off-center axis positioned near the wheel rim and spaced from the axis of rotation of the wheel, and the motor drives the wheel directly or through a rim gear at the off-center pivot point, or via drive shaft at the pivot point that transmits power to the wheel. Alternatively, the wheel axis may be supported by a Peaucellier linkage that is attached to the motor mount at fixed points and constrains the wheel axis to move along a straight line vertical path.

The ability to move each wheel independently in both direction and steering angle results in an omni-directional vehicle with the steering axis located either in or outside the wheel, or both.

These and other features and advantages of the invention may be more clearly understood by considering the detailed description which follows. In the course of this description, frequent reference will be made to the attached drawings which are summarized below.

DETAILED DESCRIPTION

An in-the-wheel, hubless suspension mechanism shown inFIGS. 1-8controls suspension movement, such as, springing, damping, and optionally, steering, camber, castor, toe-in and toe-out. The suspension system is placed inside a hubless rim101on which a tire103can be mounted. The suspension mechanism is partially or completely contained inside the space of the hubless rim101.

Ideally, the suspension mechanism consists of three active suspension elements mounted to a bracket104at the bottom of the hubless wheel. The three active elements seen at106provide the forces needed to meet all the requirements for springing and damping while providing all degrees of freedom necessary for steering, toe in, toe out, camber, and castor. Alternatively, two brackets, one at the top (at108) and one at the bottom (at104), can connect to the rim of the hubless wheel as seen inFIG. 8. The brackets104and108are connected by two guides, seen at116inFIG. 8. The sprung mounting frame118which is rigidly attached to the chassis travels vertically on the guides116.

If desired, the components of the assembly can be designed so that the steering axis goes through the center of the contact patch of the tire103, placing the tire in the optimal position relative to the road at all times, independently of the degree of steering, suspension travel, or vehicle roll and yaw. If desired, steering related functions, springing, damping, ride height, camber and castor, can be controlled independently from each other using the active components106.

The in-the-wheel suspension system attaches to the rim101by means of one (or several) clamping mechanisms104so that the hubless rim101and the tire103can rotate around their virtual axis relative the clamp104and the suspension mechanism but are otherwise rigidly connected to clamp104.

One side of a support118attaches to the suspension components106so that support118is not part of the unsprung mass. The other side of support118connects to the vehicle chassis either by means of a rigid connection or by a mechanism for adjusting castor and/ or ride height, or by a steering mechanism illustrated inFIGS. 9-12located partially or completely outside the mechanism of the hubless wheel, or by means of a leg-like mechanism seen inFIGS. 12 and 14.

A drive motor120is connected to the support118. Drive motor120is placed either completely, partially, or not at all inside the space of the hubless rim. A flexible power transmission mechanism (e.g. the belt drive see at122inFIG. 2), which is designed to function under suspension travel and steering movement, such as a belt with a tensioner, transmits power from the drive motor120to the drive mechanism124(FIG. 2) which is connected to the drive clamp(s)104and transmits power to the rim101. If minimal power transmission losses are desired, the motor can be hub-mounted as shown inFIG. 7so that the rotating components126of the motor rotate around the virtual axis of rim101, either as part of rim101or rigidly attached to rim101, while the stator elements128of the motor do not rotate around the virtual axis of rim101.

Other drive train options may be used, including: a variable-length driveshaft, a chain drive, a hydraulic drive, a scissor mechanism drive, a pneumatic muscle type drive, and others. Selected preferred drive and in-the-wheel suspension mechanisms having particular advantages include the triangular drive shaft arrangement described below in connection withFIGS. 23-29, the direct drive hinged system shown inFIG. 20, an off-center axis drive system shown inFIGS. 31-33, and an arrangement using a Peaucellier linkage that supports the wheel axis for straight line vertical motion as described in connection withFIGS. 34-36.

Braking forces are generated in one or both of two ways: by regenerative braking in the motor and by a brake disc mounted inside the wheel rim, with friction pad actuators located in the bottom bracket mechanism104. If desired, the drive mechanism, the power transmission mechanism, and the electric drive motor can be used to slow the rotation of wheel by regenerative braking, and the electricity resulting from this process can be either used directly, or it can be (temporarily) stored one or more batteries or capacitors.

Braking can also be achieved by increasing the mechanical friction between the clamping mechanism in the bracket104and the rim101, either by means of a mechanism contained in clamp104or by means of a brake disc (not shown) attached to the inside face of rim101. In case two clamps104and108are uses as illustrated inFIG. 8, they can be connected by one or more rigid elements116and these in turn connect to the vehicle chassis by the support118.

If desired, the support118or the clamping mechanism(s) in the bracket(s)104can incorporate control functions for steering, toe-in, toe-out, and camber in a way that the position of the tire relative to the ground is optimal at all times. As illustrated by the mechanism shown at130inFIGS. 5 and 6, active actuators may be used to orient the suspension supports132relative to the chassis mount134. The actuators130located at the connection bearings where the four arms connecting to the motor/chassis hold the two vertical guides132and perform all directional functions and adjustments (camber, etc). During suspension travel, the arms carrying the actuators130and the motor136remain stationary respective to the chassis at mount134. This configuration provides the following advantages:(1) space savings;(2) lower unsprung and rotational masses;(3) exact suspension geometry;(4) weight savings: since the forces are being attacked where they are being generated, the suspension components can be much lighter than in conventional suspensions;(5) steering: the steering axis is in the ideal place; and(6) independent electronic control of every wheel can improve braking and acceleration characteristics in comers and emergencies.

Since the forces are being attacked where they are being generated, they can be handled much more precisely than in conventional suspensions. castor, camber, ride height, springing, damping, and the steering axis can be controlled precisely and independently from each other at all times.

All mechanical functions of the assembly are preferably controlled electronically in a manner that results in optimal wheel position and acceleration at all times. The mounting point(s) to the vehicle are designed so that the complete wheel assemblies can be attached and detached to the vehicle rapidly and with simple means. The electronics are designed so that a given wheel assembly can function optimally for different vehicles with different weights and different dimensions at all times. The mounting point of the wheel-embedded suspension to the chassis is made in a way that the suspension unit can be removed or exchanged very easily, comparable to changing a tire on today's typical road or racing cars.

As illustrated inFIGS. 15-22, to save costs, an adaptor, such as the adapter140seen inFIG. 16, can be used to fit a mechanism of standard size (seen at142inFIG. 15) to a wheel of large inside rim diameter seen at144inFIG. 17. The resulting assembly is seen inFIG. 18.FIGS. 19-22show how a larger adapter can be used to fit the standard in-the-wheel suspension assembly to an even larger wheel using a larger adapter seen inFIG. 20. Alternatively, a different clamping mechanism104may be used with different sized rims fitting different size tires, with each clamping assembly being designed to mate with a standard size suspension mechanism.

Steering: The in-wheel steering axis may advantageously pass through the center of the wheel's contact patch. This reduces steering forces and reduces tire wear. Since the steering of all four wheels is independently controlled, the vehicle can travel diagonally while facing “forward”. The external steering axis increases the possibilities for wheel articulation, enabling the vehicle to travel in any direction on the XY plane.

By independently controlling the speed and direction of the driving motor, as well as of the in-wheel steering mechanism and the external steering mechanism on all wheels, very precise control of direction, braking, and acceleration may be achieved, especially in corners. For example, the inside wheels can brake a little more, or the outside wheels can accelerate a little more.

The control mechanism for any number of wheel robots working in conjunction to drive a vehicle can be designed so that said wheel robots know their relative positions and are able to maintain or change their relative positions in spacial and temporal patterns given specified by the control system. Instead of a (rigid) chassis providing the positioning of the wheel robots relative to each other, the control system drives each wheel robot so that desired spatial positions can be achieved at any point in time.

The motor placement options include:(1) the motor may be placed next to and inside the rim;(2) the motor may be placed next to the chassis or connectors to the chassis, (partially) inside the wheel space;(3) the motor may be placed next to the chassis-connectors, outside the wheel space (as seen inFIGS. 9-12), with an additional motor (not shown) for steering control with an external steering axis relative to the wheel such that the drive and steering operate under independent electronic control at each wheel; or(4) the motor can also be placed next to the rim, inside the wheel space.

Other Drive Mechanisms

There are additional ways to bring power from the sprung motor (which does not travel with the wheel or move with the suspension) to the unsprung wheel, which follows the road and therefore travels relative to the motor.

A second embodiment described in connection withFIGS. 23-29employs a triangular shaft201that transmits power from the motor to the wheel200from an electric motor (not shown) transmits power to the shaft201via a gear assembly203that is rotated by a motor drive gear202seen inFIG. 25. The bearing assembly houses three bearings (seen at205inFIG. 25) which make contact with the triangular shaft201, allowing little play between the bearing assembly203and the shaft201so that power may be transmitted, but allowing the shaft201to rotate with the bearing assembly203about the shaft axis, and also allowing the shaft201to move longitudinally along the axis of the triangular shaft201. In this way, the shaft201can travel along its longitudinal axis relative to gear assembly203, and hence relative to the motor and chassis, as the wheel rim204moves up and down. One or both ends of the triangular shaft201form a gear as seen at206inFIG. 23that engages with a crown gear207that is attached to the rim204, thereby transmitting power between the shaft201and the rim204. This mechanism allows transmission of power both from the motor to the wheel and from the wheel to the motor during deceleration when energy is regeneratively returned to the battery from the electric motor that acts as a generator.

As seen inFIG. 23, the triangular shaft201is aligned at a slight angle with respect to the vertical, allowing the two ends of the shaft to engage with one of the two crown gear207and209. The suspension supporting springs, one of which is indicated at210inFIG. 24, are aligned parallel to the triangular shaft201. As the wheel moves up and down during vehicle travel, the entire wheel and hub assembly move laterally by a slight amount with respect to the sprung chassis as the triangular shaft201moves up and down through the bearing assembly203.

Alternatively, as shown inFIG. 26, the wheel may be tilted at an angle so that the camber is equal to the tilt of the shaft with respect to the wheel. Any additional camber would be added by adjusting the suspension system (tilting the motor, etc) using a mechanism of the type shown inFIGS. 5 and 8. As seen inFIG. 27, the angle of tilt can be designed to be very small (less than two degrees).

To totally eliminate lateral movement, the triangular shaft may be aligned vertically, and employ only one shaft gear and rim gear as seen inFIG. 28, or the two rim gears207and209on the inner and outer sides of the hub may be of different diameters so that each shaft-end gear engages with one of the rim gears but is vertically displaced from the other rim gear as illustrated inFIG. 29.

The drive arrangements shown inFIGS. 26-29, as with the drive arrangements described above in connection withFIGS. 1-25, employ suspension springs and dampers seen at210inFIG. 24. The springs/dampers210support a sprung motor mount212and extend between the upper and lower portions of a bracket frame216. The bracket frame216engages with the inside of the rim via the roller bearings218. The triangular drive shaft201is journaled to a supportframe217which holds it in proper position so that its end gears engage with the rim gears.

A third embodiment shown inFIG. 30employs three drive gears303,305and306arranged in a triangular formation so that one gear303(the motor gear) is driven by the motor and transmits power to a middle gear305which in turn transmits power to a third gear306(the rim gear) which is in constant contact with and engages the crown gear309attached to the rim. The angle between the links311and313which support the gears, and therefore the distance between the motor gear303and the rim gear306, is variable, allowing the gears to be continuously engaged and deliver power during up and down travel of the wheel315. The motor gear is rigidly attached to the sprung frame member320that is supported by the springs322.

Off-center Traveling Suspension Axis

As more components are added to the hub or the unsprung portions of the suspension, unsprung mass increases. The arrangements described above suspend the tire and the rim in a way that allows maximum suspension travel while keeping all other components (motor, drive-force transmission, steering, suspension and activators) inside the wheel stable and consequently sprung. The fourth embodiment shown inFIGS. 31 and 32employ an off-center suspension traveling axis indicated along the dashed line403as shown inFIG. 31. The axis403sitting near the rim and outside the wheel center axis405allows the wheel to travel up and down as the support arm407pivots about the off-center axis403. The advantage of this wheel suspension design is that the suspension axis can easily be used to drive the wheel directly or function as the drive force transmission axis. As seen inFIG. 31, the shaft of the drive motor411drives the belt413which is coupled to a drive shaft that rotates about the off-center axis403and in turn drives the wheel hub using a second drive belt seen at415.

This suspension mechanism uses a single simple mechanical link, the pivoting support arm407. The motor support member seen at420is rigidly attached to the chassis and supports both the motor411and the pivot shaft at off-center suspension axis403. The pivoting support arm407and the motor411are thus supported inside the wheel hub and all of the attached components remain stable. The wheel hub rotates about a shaft at423journaled by ball bearings to pivoting support arm407. The hub drive shaft423is driven by the drive belt415. When the wheel hits a bump, the wheel axis at shaft423is urged upwardly and the pivoting support arm407pivots upwardly about the off-center axis403, compressing a support spring/damper at425. Alternatively, one or several rotational springs and/ or dampers can be located on or near off-center axis403.

Steering can be achieved by rotating one or several support members420relative to chassis connectors429around steering axis427. Steering axis427may or may not pass through the center of the contact patch, and steering axes as shown inFIGS. 9 to 12, as well as movable legs, as shown inFIGS. 13 to 14, may or may not be employed. The movable legs shown inFIGS. 13-14may be coupled to actuators (not shown) which permit the position and orientation of the steering axis, and the location of the wheel relative to the chassis, to be moved to change the handling characteristics of the vehicle.

Camber and castor may be achieved by moving the mounts of steering axis427relative to chassis connectors429. Alternatively, camber can be achieved by having two parallel support members420, rotating in conjunction around a common steering axis427for steering, and rotating independently around the virtual center axis of motor411, thereby tilting off-center axis403relative to motor411and chassis connectors429.

In an alternative “hubless” arrangement illustrated inFIG. 35, an inner rim560is positioned inside and is separated from the wheel rim by roller bearings (not shown). The entire wheel and the inner rim560pivots about the off-center suspension axis seen at570. A mounting bracket at580is rigidly attached to the chassis and to the motor seen at585. A drive gear590rotates about the off-center axis570to engages with and drive a rim gear (not shown) rigidly attached to the outer wheel rim. The drive gear590is driven by the motor585by a belt, gears, or the like (not shown). A support spring/damper at595is compressed when the wheel pivots upwardly about the off-center pivot axis570.

Both designs seen inFIGS. 34 and 35thus include an off-center suspension axis and drive shaft combination and both form a self-contained wheel robot with an off-center axial traveling suspension using the suspension axis as the drive shaft (as inFIG. 35), or as the drive-force transmission shaft (as inFIG. 34).

FIG. 33shows how the off-center suspension moves relative to the wheel as the vehicle is driven over an uneven surface. Comparing the wheel position at the left with the elevated wheel position in the center, it can be seen that the support arm (seen at407inFIG. 31) pivots upwardly, compressing the spring/damper, as the wheel moves up. The wheel position at the right has dropped, pivoting the support arm in a clockwise direction about the off-center pivot point, and the support spring is fully elongated. Thus, as the wheel pivots vertically when the vehicle is driven over an uneven surface, only the tire, rim and hub (if a hub is used), and the pivoting support arm move, thus minimizing the unsprung mass.

The embodiment of the invention shown inFIGS. 34-36employs a Peaucellier mechanism to support the axis of a wheel hub at two fixed pivot points by an arrangement of links. The Peaucellier mechanism is described in “Mechanisms, Linkages, and Mechanical Controls”, edited by Nicholas P. Chironis, published by McGraw-Hill, Inc. 1965; and “Ingenious Mechanisms For Designers and Inventors”, Vols. I and II, edited by Franklin D. Jones, The Industrial Press, 1935. In one illustrative form shown inFIG. 34, the mechanism consists of seven pieces or links joined at the points designated by the letters A-F. There are two long links AD and AE of equal length, four short links that form a rhombus CDEF, and a link BC which pivots about a fixed point B. The points A is also fixed. The point C is thus constrained by the link BC to move in a circular path indicated at601about point B as the link BC rotates. The remaining links constrain point F to move in along a straight line path603.

Rotary motion of arm BC around Point B is thus translated into vertical motion of Point F. Point A can also lie within the parallelogram formed by CEFD, without affecting the function of the mechanism. The resultant linear motion of point F is along a true straight line, not just an approximation as it is for other mechanisms such as the well known Watt linkage described, along with other straight line linkage mechanisms, in U.S. Pat. No. 4,545,266 issued to Brems on Oct. 8, 1985 entitled “Straight line linkage.” True vertical travel is an important component of suspension system and use of the Peaucellier mechanism accordingly provides an improvement over the pivot arm embodiments seen inFIGS. 31 and 32which use a pivot point that carries the axis of the wheel hub in along an arc-shaped path.

FIG. 35illustrates the manner in which a Peaucellier linkage may be used to support a wheel hub axis for straight line vertical motion. The linkage mechanism is attached to the motor mount plate700at the two fixed pivot points701and702as seen inFIG. 36. The motor mounting plate700is rigidly attached to motor706and the vehicle chassis (not shown). The four links joined at pivot points703,705,707and709form a rhombus (a parallelogram with four equal length sides). The pivot point at705is constrained to move in a circular path by the link between point705and the fixed pivot point702. The linkage then constrains the pivot point709attached to the wheel hub axis to move along a straight vertical path as indicated by the arrow711inFIG. 36which shows how the linkage moves when the wheel is forced upward as seen at the right when the wheel strikes a bump.

Because all of the links are of fixed length, power can be transmitted from the motor shaft to the wheel using two belts, the first of which connects the motor drive an intermediate shaft which rotates about fixed point701and the second of which follows a path around the pivot points701,707,709and703. Because these four points are joined by fixed length links, the path length of the belt is fixed. The belt rotationally engages the drive shaft the rotates about point701as well as the hub axis that rotates about point709, and idler pulleys (not shown) at pivot points703and707maintain the drive belt tension.

A conventional spring and damper (not shown) may be positioned to absorb forces between the fixed motor mount (chassis)700and the wheel hub axis at709. Alternatively, or in addition, one or more rotary springs may be positioned at either or both of the fixed position pivot points701and702. Each such rotational spring absorbs the rotational forces applied between the mounting plate700and the link attached at that fixed pivot point.

Alternatively to roller or ball bearings, fluid bearings or magnetic mechanisms may be used to support the hubless wheel. Any bearings or other moving mechanisms may be covered appropriately to protect them from the elements, or to reduce hazards arising from moving parts or parts carrying electricity or generating high magnetic fields.

Control System

The present invention provides a self-contained, single-wheel, electric motor drive and suspension system that can be independently controlled. Such a self-contained “wheel robot” can used for each wheel of a four wheeled automobile as illustrated inFIG. 37(or in a two wheeled motorcycle, or a train of articulated multi-wheeled vehicles such as a tractor-trailer-like vehicle). Each wheel assembly incorporates every component needed to drive, steer, suspend and lean a car wheel as required in an automobile or other vehicle. Attached to a chassis with a minimal number of connection points, these self-contained wheel robots only require electrical power and driving data to propel a vehicle. For example, as seen inFIG. 37, a central controller801receives signals from sensors802located in the vicinity of the wheel (including both displacement sensors and accelerometers for monitoring the dynamic state of the wheel system) and delivers control signals to actuators within each wheel robot. The availability of such a self-contained wheel robot can radically simplify car design, especially chassis design and engineering which become much easier, faster and cheaper because the chassis no longer houses components such as the motor, drive shaft and gear box.

Instead of a rigid chassis holding the wheels in place, the central wheel controller801(or a distributed computing system using separate controllers at each wheel which communicate with one another as needed) coordinates the action of the wheel robots to perform that function. Using position sensors at each wheel location, the computing system can control any number of wheel robots that work together to drive a vehicle or a set of connected vehicles so that each wheel is positioned relative to the others in a desired configuration, such as at the corners of a square where the wheels are typically positioned by a rigid automobile chassis. Using independently controlled and positioned wheel robots, the control system can be designed such that it directs those wheel robots to maintain that square, without the need for a rigid mechanical link to perform that function. The control signals from the central controller delivered to each wheel robot controls the amount of power applied to the drive motor803, the amount of braking created regeneratively by the motor803and a disk brake mechanism805or the like, and the rotation of the wheel about its steering axis controlled by a steering actuator807.

The dynamic forces to which each wheel is subjected during driving are attacked where they are generated, allowing for lighter components, more precise suspension control (ride, handling, steering axis, reducing tire wear). The suspension elements, generally indicated at808inFIG. 37, that have been described above can control different suspension aspects (camber, castor, toe in, ride height, steering angle, springing, damping) independently from each other. The suspension elements which support the wheel with respect to the chassis may consist of both conventional passive spring and shock absorbing systems, as well as active suspension elements which include powered actuators which apply forces between the chassis and each wheel, the magnitude of the forces being continuously computed by the controller801in accordance with optimization routines which may themselves be adaptively altered in response to changing driving conditions. For example, an active suspension control system of the type described in U.S. Pat. No. 5,519,612 issued on May 21, 1996 to Liubakka et al entitled “Active Suspension System with Adaptive Actuator Gain Adjustment” describes a system for adaptively controlling suspension forces and ride heights to improve passenger comfort and handling over a variety of road surfaces. By independently controlling wheel position variables including toe-in, toe-out, castor, and steering, the suspension elements can be adjusted to perform equally well in the “forward” and “reverse” direction at any speed. The steering axis may be positioned in the center of the tire contact patch or at the linkage point between the suspension and the chassis, or both, permitting the construction of a truly omni directional vehicle. As previously discussed, the position and orientation of each wheel may be adjusted using actively movable “legs” which attach each wheel assembly to the chassis, allowing the behavior of the system may be dynamically controlled to provide improved on-road speed and handling with excellent off-road capability.

CONCLUSION

It is to be understood that the methods and apparatus which have been described above are merely illustrative applications of the principles of the invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention.