Abstract:
An active suspension system for a truck cabin that actively responds to and mitigates external force inputs between the truck chassis and the cabin. The system greatly reduces pitch, roll, and heave motions that lead to operator discomfort. The assembly is comprised of two or more self-contained actuators that respond to commands from an electronic controller. The controller commands the actuators based on feedback from one or more sensors on the cabin and/or chassis.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application PCT/US2014/029654, entitled “ACTIVE VEHICLE SUSPENSION IMPROVEMENTS”, filed Mar. 14, 2014, which claims the benefit under 35 U.S.C. §119(e) of U.S. provisional application Ser. No. 61/913,644, entitled “WIDE BAND HYDRAULIC RIPPLE NOISE BUFFER”, filed Dec. 9, 2013, U.S. provisional application Ser. No. 61/865,970, entitled “MULTI-PATH FLUID DIVERTER VALVE”, filed Aug. 14, 2013, U.S. provisional application Ser. No. 61/815,251, entitled “ACTIVE SUSPENSION”, filed Apr. 23, 2013, and U.S. provisional application Ser. No. 61/789,600, entitled “ACTIVE SUSPENSION”, filed Mar. 15, 2013, the disclosures of which are incorporated by reference in their entirety. This application also claims the benefit under 35 U.S.C. §119(e) of U.S. provisional application Ser. No. 61/930,452, entitled “ELECTROHYDRAULIC SYSTEMS”, filed Jan. 22, 2014, the disclosure of which is incorporated by reference in its entirety. 
    
    
     FIELD 
     Disclosed embodiments are related to an active stabilization system for truck cabins. 
     BACKGROUND 
     Existing commercial trucking vehicles consist of a vehicle operator cabin that is suspended from the vehicle chassis in an attempt to passively or semi-actively mitigate the harsh mechanical road inputs that the chassis experiences. Some modern systems use passive dampers to reduce the amount of heave, pitch, and roll felt by the vehicle operator. Semi-active systems use sensors and control protocols that further reduce the effects of these inputs. Active cabin stabilization systems exist that use vibration isolators to mitigate small cabin motions and vibration. The active stabilization system detailed in this patent uses sensors such as accelerometers and gyroscopes to measure forces that result from the vehicle&#39;s interaction with its environment, such as mechanical road inputs, and transmits the inputs to a controller which interprets the inputs and commands the appropriate force responses to actuators located between the operator cabin and chassis of the vehicle. The system uses a feed-forward approach to predict movements that the cabin will experience and command the actuators to respond appropriately to isolate the movement. The system greatly reduces pitch, roll, and heave motions, which may lead to operator discomfort. 
     SUMMARY 
     Aspects of the invention relate to a commercial vehicle cabin stabilization system that actively responds to external force inputs from the road using sensors to monitor mechanical road input, and at least one or a plurality of controllers to command force outputs to at least one or a plurality of electro-hydraulic actuators to isolate the cabin from these inputs. 
     According to one aspect, the system is comprised of a plurality of electro-hydraulic actuators, each actuator comprising an electric motor operatively coupled to a hydraulic pump, and a closed hydraulic circuit, wherein each of the plurality of electro-hydraulic actuators is disposed between structural members of the chassis and cabin of the vehicle. 
     According to another aspect, the system has at least one sensor to sense movement in at least one axis of at least one of the cabin and the chassis. 
     According to another aspect, the system has a control program executing on at least one controller to activate at least one of the plurality of electro-hydraulic actuators in response to the sensed movement, wherein the activated at least one of the plurality of electro-hydraulic actuators operates to isolate at least a portion of the chassis movement from the cabin. 
     In some embodiments, the control program causes current to flow through the electric motor to at least one of induce rotation of the hydraulic motor thereby inducing hydraulic fluid flow through the actuator and retard rotation of the hydraulic motor thereby reducing movement of the actuator. 
     In some embodiments, the electro-hydraulic actuator hydraulic pump has a first port and a second port, wherein the first port is in fluid communication with the first side of a hydraulic cylinder, and the second port is in fluid communication with the second side of the hydraulic cylinder, and each actuator further comprises of an accumulator. 
     In some embodiments, each actuator further comprises a dedicated controller and each dedicated controller executes a version of the control program. 
     In some embodiments, at least one electro-hydraulic actuator operates to control roll, pitch, and heave of the cabin. 
     In some embodiments, at least one electro-hydraulic actuator is disposed perpendicular to the vehicle chassis and cabin. 
     In some embodiments, at least one electro-hydraulic actuator is disposed at a non-perpendicular angle between the chassis and cabin. 
     In some embodiments, the system can control fore and aft motion of the cabin. 
     In some embodiments, the plurality of sensors are adapted to detect vehicle acceleration in at least two axes. 
     In some embodiments, the plurality of sensors are feed-forward sensors and adapted to detect at least one of steering angle, brake application, and throttle. 
     In some embodiments, the plurality of sensors includes a sensor to detect movement of the operator&#39;s seat. 
     In some embodiments, the cabin is a front hinged cabin and the plurality of electro-hydraulic actuators comprises of two actuators operatively connected to the rear of the cabin. 
     In some embodiments, the cabin is four-point suspended cabin and the plurality of electro-hydraulic actuators comprises of four actuators operatively connected to each corner of the cabin. 
     In some embodiments, the system further is comprised of the least of one and a plurality of actuators disposed between a operator&#39;s seat and the cabin, wherein the least of one and a plurality of controllers for the least of one and a plurality of seat actuators communicate with the cabin suspension actuators. 
     In some embodiments, energy in the actuator is consumed in response to a command force. 
     According to one aspect, the system is a vehicle cabin stabilization system comprising a plurality of electro-hydraulic actuators, each actuator comprising an electric motor operatively coupled to a hydraulic pump, and a closed hydraulic circuit, wherein each of the plurality of electro-hydraulic actuators is disposed between structural members of the chassis and cabin of the vehicle; 
     According to another aspect, there is at least one sensor for determining movement of the vehicle in at least two axes. 
     According to another aspect, there is a control program executing on the controller to activate the plurality of electro-hydraulic actuators in response to the sensed vehicle movement, wherein the activated plurality of electro-hydraulic actuators cooperatively operate to isolate at least a portion of pitch, roll, and heave motions of the cabin from the determined vehicle movement. 
     In some embodiments, the plurality of sensors disposed to sense movement of the vehicle sense at least one of the chassis, the wheels, a seat, and the cabin. 
     In some embodiments, the control program causes current to flow through the electric motor to at least one of induce rotation of the hydraulic motor thereby inducing hydraulic fluid flow through the actuator and retard rotation of the hydraulic motor thereby reducing movement of the actuator. 
     In some embodiments, the electro-hydraulic actuator hydraulic pump has a first port and a second port, wherein the first port is in fluid communication with the first side of a hydraulic cylinder, and the second port is in fluid communication with the second side of the hydraulic cylinder, and each actuator further comprises of an accumulator. 
     In some embodiments, each actuator further comprises a dedicated controller and each dedicated controller executes a version of the control program. 
     In some embodiments, at least one electro-hydraulic actuator is disposed perpendicular to the vehicle chassis and cabin. 
     In some embodiments, at least one electro-hydraulic actuator is disposed at a non-perpendicular angle between the chassis and cabin. 
     In some embodiments, the system can control fore and aft motion of the cabin. 
     In some embodiments, the plurality of sensors are feed-forward sensors and adapted to detect at least one of steering angle, brake application, and throttle. 
     In some embodiments, the plurality of sensors includes a sensor to detect movement of the operator&#39;s seat. 
     In some embodiments, the cabin is a front hinged cabin and the plurality of electro-hydraulic actuators comprises of two actuators operatively connected to the rear of the cabin. 
     In some embodiments, the cabin is four-point suspended cabin and the plurality of electro-hydraulic actuators comprises of four actuators operatively connected to each corner of the cabin. 
     In some embodiments, the system is further comprised of the least of one and a plurality of actuators disposed between a operator&#39;s seat and the cabin, wherein the least of one and a plurality of controllers for the least of one and a plurality of seat actuators communicate with the cabin suspension actuators. 
     In some embodiments, energy in the actuator is consumed in response to a command force. 
     According to one aspect, the system is a method of secondary vehicle suspension wherein a plurality of controllable electro-hydraulic actuators are disposed between a structural member of a vehicle chassis and a structural member of a cabin of the vehicle. 
     According to another aspect, sensed movement information is received on at least one of the plurality of self-controllable electro-hydraulic actuators. 
     According to another aspect, the plurality of controllable electro-hydraulic actuators are controlled to mitigate the impact of the sensed vehicle movement on the cabin by applying current to at least one electric motor that controls movement of the hydraulic fluid through one of the plurality of actuators by at least one of resisting and assisting rotation of a hydraulic pump that engages the hydraulic fluid. 
     In some embodiments, the electric motor is immersed in hydraulic fluid with the pump. 
     In some embodiments, movement of the vehicle is measured the cabin, the chassis, the wheels, or some combination of the three. 
     According to one aspect, the system is a method of secondary vehicle suspension wherein a plurality of self-controllable electro-hydraulic actuators are disposed between a structural member of a vehicle chassis and a structural member of a cabin of the vehicle. 
     According to another aspect, sensed movement information is received on at least one of the plurality of self-controllable electro-hydraulic actuators. 
     According to another aspect, the movement of the cabin is mitigated by controlling rotation of a hydraulic motor of the self-controllable electro-hydraulic actuator that at least partially determines hydraulic fluid pressure within the self-controllable electro-hydraulic actuator in response to the sensed movement. 
     In some embodiments, each of the plurality of self-controllable electro-hydraulic actuators responds independently to the sensed movement. 
     In some embodiments, each of the plurality of self-controllable electro-hydraulic actuators comprises at least one local sensor to sense movement of the vehicle. 
     In some embodiments, each of the plurality of self-controllable electro-hydraulic actuators responds cooperatively to the sensed movement by communicating with at least one other of the plurality of self-controllable electro-hydraulic actuators. 
     According to one aspect, the system is a method of secondary vehicle suspension, which senses movement of a vehicle chassis. 
     According to another aspect, a reactive movement of a cabin of the vehicle based on the sensed movement is predicted. 
     According to another aspect, a plurality of controllable electro-hydraulic actuators disposed between a structural member of the vehicle chassis and a structural member of the cabin are controlled to counteract a portion of the predicted reactive movement that impacts at least one of roll, pitch and heave of the cabin. 
     In some embodiments, controlling comprises applying current to at least one electric motor that controls movement of the hydraulic fluid through one of the plurality of actuators by at least one of resisting or assisting rotation of a hydraulic pump that engages the hydraulic fluid. 
     According to one aspect, the system is a method of secondary vehicle suspension wherein movement of a vehicle cabin is sensed using an accelerometer, a gyroscope, a position sensor, or some combination of the three. 
     According to another aspect, a plurality of controllable electro-hydraulic actuators disposed between a structural member of the vehicle chassis and a structural member of the cabin are controlled to counteract a portion of the cabin movement in the roll, pitch and heave modes of the cabin. 
     In some embodiments, controlling comprises applying current to at least one electric motor that controls movement of the hydraulic fluid through one of the plurality of actuators by at least one of resisting or assisting rotation of a hydraulic pump that engages the hydraulic fluid. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numerical. For purposes of clarity, not every component may be labeled in every drawing. 
         FIG. 1  is a schematic representation of a four point active truck cabin stabilization system. Shown in the breakout view are four electro-hydraulic actuators, four springs (represented here as air springs but can be any type of self-contained device acting as a spring), a plurality of sensors, a plurality of controllers, and the main structures that make up the vehicle. 
         FIG. 2  is a schematic representation of a three point active truck cabin stabilization system. Shown in the breakout view are two electro-hydraulic actuators, two springs (represented here as air springs but can be any type of self-contained device acting as a spring), a plurality of sensors, a plurality of controllers, a hinge mechanism, and the main structures that make up the vehicle. 
         FIG. 3  is an isometric view of an isolated assembly of a three point active truck cabin stabilization system. 
         FIG. 4  is an embodiment of an active suspension actuator that comprises a hydraulic regenerative, active/semi-active damper smart valve. 
         FIG. 5  is an embodiment of a regenerative active/semi-active smart valve. 
     
    
    
     DETAILED DESCRIPTION 
     The secondary vehicle stabilization system detailed herein uses a feed forward approach to receiving road inputs and triggering actuator response prior to the mechanical road input reaching the operator cabin. The system is able to accurately predict the motion of the operator cabin with ample time to apply force responses to the actuators. The system detailed herein provides for optimal stabilization of an operator cabin on a truck. The electro-hydraulic actuators included in the system are detailed below. 
     Referring to  FIG. 1 , as a truck drives over a road event such as a pothole or unevenness in the road, a mechanical force input is introduced into the chassis of the vehicle  10 - 108  through the wheel  10 - 112 . By placing sensors (accelerometers, position sensors, gyroscopes, etc.)  10 - 110  on the vehicle chassis  10 - 108  or on the suspension to measure wheel motion, the mechanical input is registered by a controller(s)  10 - 114 . By sensing these external force inputs on the vehicle chassis or suspension, the sensors provide information to the controller pertaining to the forces that may generate cabin disturbances, before they can affect the cabin and far enough in advance of the input being transmitted to the cabin  10 - 104  that the system is able to predict the pitch, roll, and heave motions that will be transmitted to the operator cabin. This allows ample time for one or more controllers  10 - 114  to deliver commands for force outputs to one or more electro-hydraulic actuators  10 - 102 . The system is therefore able to eliminate the pitch, roll, and heave motions felt by the vehicle operator, making the active stabilization system a feed-forward system. 
     The electro-hydraulic actuator  10 - 102  comprises an electric motor operatively coupled to a hydraulic pump and a closed hydraulic circuit that is able to create controlled forces in multiple (e.g., typically three or four) quadrants of a damper/actuator force-velocity curve, whereby the four quadrants of the force-velocity profile of the hydraulic actuator correspond to compression damping, extension damping, active extension, and active compression. When an active force output is commanded to an actuator, energy is consumed by the actuator; conversely, when the actuator is operating in the damping regime, the actuator is regenerative, and energy is generated by the actuator that can be stored or used by the system. 
     In the embodiment shown in  FIG. 1  the electro-hydraulic actuators  10 - 102  are coupled between the chassis  10 - 108  and the cabin  10 - 104 . Springs  10 - 106  are also coupled between the chassis and the cabin and operate mechanically in parallel with the actuators  10 - 102 . The electro-hydraulic actuators  10 - 102  and the springs  10 - 106  may be the only structural members between the chassis  10 - 108  and the cabin  10 - 104 , or there may be additional supporting structures that do not inhibit the actuation of the actuators  10 - 102  or the springs  10 - 106 . 
     The actuators  10 - 102  may be disposed such that they are oriented perpendicular to the chassis  10 - 108  and the cabin  10 - 104 , for example along the y axis as it is shown in  FIG. 1 . When installed in this orientation, the actuators  10 - 102  may impart force outputs on the chassis  10 - 108  and the cabin  10 - 104  in the direction of the y axis. In some embodiments, this orientation may be sufficient to mitigate the effects of external force inputs on the cabin such as pitch, roll, and heave. In other embodiments where this may not be sufficient the actuators  10 - 102  may be disposed such that they are oriented at a non-perpendicular angle between the chassis  10 - 108  and the cabin  10 - 104 . In this orientation, the actuators  10 - 102  may impart a force output with some component in any of the x, y, or z directions, which may further assist in controlling fore and aft motions of the cabin. 
     The electro-hydraulic actuator  10 - 102  may comprise of an integral (or dedicated) motor controller  10 - 114 , wherein the electronic controller  10 - 114  may comprise of both power and logic capabilities and may also include sensors, such as a rotary position sensor, accelerometer, gyroscopes, or temperature sensors etc. The controller may comprise a control program (or protocol) whereby the controller executes a program in response to the sensed vehicle movement or other input that causes current to flow through the electric motor to either induce rotation of the hydraulic motor thereby inducing hydraulic fluid flow through the actuator or to retard rotation of the hydraulic motor thereby reducing movement of the actuator to isolate at least a portion of pitch, roll, and heave motions of the cabin from the determined vehicle movement. 
     The electronic controller  10 - 114  may utilize signals from the integral sensors and/or utilize signals from external sensors such as suspension position sensors, chassis accelerometers, wheel accelerometers, vehicle speed sensors and the like to isolate at least a portion of pitch, roll, and heave motions of the cabin from the determined vehicle movement. The electronic controller may also have the capability to communicate with other vehicle systems (via the controller area network (CAN) bus, FLEXRAY or other communication protocols). These systems may include the other electro-hydraulic actuator controllers installed on the vehicle, an electro-hydraulic actuator central controller etc., as well as non-suspension related vehicle systems such as steering, brake and throttle systems etc. The system may use at least one of the accelerometers, position sensors or gyroscopes for monitoring chassis disturbances from wheel events or inertial effects on the cabin in any combination of axes, whereby any of these sensors may be able to detect vehicle acceleration in at least two axes. Other sensors may assist in predicting the movement of the vehicle or portions of the vehicle, which can aid in the mitigation of the sensed movements on the cabin  10 - 104 . These sensors can be mounted in various locations, wherein sensors mounted on the wheels or suspension members that are coupled to the wheels may be the first to experience external force inputs from the road. Sensors mounted on the chassis  10 - 108  or the cabin  10 - 104  can monitor the inputs felt by their respective structures. Sensors mounted on the operator&#39;s seat may provide an accurate mapping of the inputs felt by the operator. Sensors mounted on the controlling instrumentation of the vehicle such as the steering system, the braking system, or the throttle system can provide input which might allow the system to predict disturbances that may affect the cabin. Sensors mounted near the actuators  10 - 102  can provide realistic data pertaining to the appropriate force output that should be commanded to the respective actuator  10 - 102 . The term “sensor” should be understood, except where context indicates otherwise, to encompass all such analog and digital sensors, as well as other data collection devices and systems, such as forward-looking cameras, navigation and GPS systems that provide advance information about road conditions, and the like that may provide input to the controllers described herein. 
     The system may comprise of a plurality of self-controllable electro-hydraulic actuators  10 - 102 , wherein a self-controllable actuator  10 - 102  may comprise an integral sensor  10 - 110 , a controller  10 - 114 , accumulator, hydraulic pump, and electric motor, and may further comprise local power storage. The controller  10 - 114  may comprise an independent control algorithm to control the actuator  10 - 102  based solely on input gathered by the integrated sensor, thereby each actuator  10 - 102  may operate independently of the other actuators  10 - 102  in the system. In some embodiments, the self-controllable actuators  10 - 102  may operate in unison to improve the ability of the system to mitigate cabin  10 - 104  movement. 
     In the embodiment of  FIG. 1  a four point active stabilization system is disclosed. The system comprises four electro-hydraulic actuators  10 - 102 , four springs  10 - 106  (in the embodiment disclosed the springs are represented as air springs, but these may be mechanical springs such as coil springs, torsion springs leaf springs etc. as the disclosure is not limited in this regard), at least one controller(s)  10 - 114 , and at least one sensor(s)  10 - 110  (accelerometers, etc.), wherein the four electro-hydraulic actuators may be located proximal to the four corners of the cabin  10 - 104 , wherein the four springs operate mechanically in parallel with the actuators. 
     An actuator(s)  10 - 102  may be mounted between the operator&#39;s seat (not shown) and the vehicle cabin  10 - 104 . These actuators  10 - 102  can be self-controllable or they can communicate with the actuators disposed between the cabin  10 - 104  and the chassis  10 - 108 . In the latter case, the actuators  10 - 102  located at the operator&#39;s seat can be substantially more predictive of the movements that will be experienced by the operator and can respond appropriately. The seat actuators  10 - 102  may be coupled to a spring  10 - 106  in a similar fashion to the cabin actuators  10 - 102 . 
       FIG. 2  depicts an embodiment of a truck with three point assembly active stabilization system, wherein the system comprises of two electro-hydraulic actuators  10 - 102  coupled between the chassis and the cabin, two springs  10 - 106  operating mechanically in parallel with the actuators (in the embodiment disclosed these are represented as air springs but may be any form of spring), at least one and at most three controllers  10 - 114 , and at least one and at most four sensors  10 - 110  (e.g. accelerometers, position sensors, gyroscopes etc.), wherein the two rear corners of the vehicle operator cabin  10 - 104  are coupled to the vehicle chassis  10 - 108  via actuators  10 - 102  and springs  10 - 106 , wherein the front of the vehicle operator cabin  10 - 104  is pivotally connected to the vehicle chassis  10 - 108  via a hinge mechanism  10 - 202 , whereby the cabin  10 - 104  has the ability to translate and rotate in at least one of the x, y, and z axes. 
     Actuators  10 - 102  may be mounted between the operator&#39;s seat (not shown) and the vehicle cabin  10 - 104 . These actuators  10 - 102  can be self-controllable or they can communicate with the actuators disposed between the cabin  10 - 104  and the chassis  10 - 108 . In the latter case, the actuators  10 - 102  located at the operator&#39;s seat can be substantially more predictive of the movements that will be experienced by the operator and can respond appropriately. The seat actuators  10 - 102  may be coupled to a spring  10 - 106  in a similar fashion to the cabin actuators  10 - 102 . 
     In  FIG. 3  is an isometric view of an isolated assembly of a three point active truck cabin stabilization system is disclosed showing the two electro-hydraulic actuators  10 - 102 , the two air springs  10 - 106 , a vehicle chassis member  10 - 108 , the pivoting hinge mechanism  10 - 202  and an articulating cabin support member  10 - 204 . 
     In  FIG. 4  an example of an actuator  10 - 102  utilized in a three point and four point active truck cabin stabilization system is disclosed. The actuator  10 - 102  is driven by a hydraulic pump that is coupled to an electric motor. The actuator  10 - 102  has a central axis of actuation  10 - 432 . As a current is applied to the electric motor by the controller  10 - 114 , to either assist or resist in the rotation of a hydraulic pump. This rotation causes the hydraulic pump to channel fluid through the actuator  10 - 102 . Depending on the direction of the applied rotational torque, the channeling of hydraulic fluid causes the piston of the actuator  10 - 102  to translate in either the compression stroke or the rebound stroke along the central axis of actuation  10 - 432 . The actuator  10 - 102  is coupled between the vehicle operator cabin  10 - 104  and the vehicle chassis  10 - 108  by means of a top mounting mechanism and a bottom mounting mechanism. An example of a top mounting mechanism is provided for mounting to the vehicle operator cabin. An example of a bottom mounting mechanism is provided for mounting to the vehicle chassis. The location of the mounting point on the vehicle operator cabin for affixing the top mounting mechanism and the location of the mounting point on the vehicle chassis for affixing the bottom mounting mechanism may be located such that the central axis of actuation  10 - 432  has some component in each of the x, y, and z axes. This enables each actuator  10 - 102  to affect the movement of the vehicle operator cabin in each of the aforementioned axes. 
       FIG. 4  shows an embodiment of the electro-hydraulic actuator that comprises a hydraulic regenerative, active/semi-active smart valve  10 - 406  and a hydraulic actuator  10 - 402 . The hydraulic actuator  10 - 402  comprises an actuator body (housing)  10 - 404 . The smart valve  10 - 406  is close coupled to the actuator body  10 - 404  so that there is a tight integration and short fluid communication between the smart valve and the actuator body, and is sealed so that the electro-hydraulic smart valve assembly becomes a single body actuator. In the embodiment shown in  FIG. 4  the smart valve  10 - 406  is coupled to the actuator body  10 - 404  so that the axis of the smart valve (i.e. the rotational axis of the integrated HSU and electric motor)  10 - 430  is parallel with the actuator body, although the smart valve may be orientated with its axis  10 - 430  perpendicular to the actuator axis  10 - 432  or at some angle in between. 
     The integrated smart valve  10 - 406  comprises of an electronic controller  10 - 408 , an electric motor  10 - 410  that is close coupled to a hydraulic pump/motor (HSU)  10 - 412 . The HSU has a first port  10 - 414  that is in fluid communication with a first side  10 - 416  in the actuator body  10 - 404  and a second port  10 - 418  that is in fluid communication with a second side  10 - 420  in the actuator body  10 - 404 . The first port and second port comprises a fluid connection to the actuator wherein, the hydraulic connection comprises a first tube inside a second tube, wherein the first port is via the first tube, and the second port is via the annular area between the first tube and second tube. In an alternate embodiment the hydraulic connection may comprise of two adjacent ports. Hydraulic seals are used to contain the fluid within the first and second hydraulic connections as well as to ensure that fluid is sealed within the actuator. It is well understood to anyone skilled in the art that many other permutations of hydraulic connection arrangements can be constructed and the patent is not limited in this regard. 
     In the embodiment disclosed in  FIG. 4  the first side represents an extension volume and the second side represents a compression volume; however, these chambers and volumes may be transposed and the disclosure is not limited in this regard. The HSU  10 - 412  is in hydraulic communication with a piston  10 - 422  and piston rod  10 - 424  so that when the piston and piston rod moves in a first direction (i.e. an extension stroke) the HSU rotates in a first rotation, and when the piston and piston rod moves in a second direction (i.e. a compression stroke) the hydraulic motor rotates in a second rotation. The close coupling of the HSU first and second ports with the extension and compression chambers of the actuator allows for a very stiff hydraulic system, which is very favorable for the responsiveness of the active suspension actuator. 
     The active suspension actuator  10 - 402  may have a high motion ratio from the linear speed of the piston  10 - 422  and piston rod  10 - 424  to the rotational speed of the close coupled HSU and electric motor, and during high velocity events extremely high rotational speeds may be achieved by the closely coupled HSU and electric motor, which may cause damage to the HSU and electric motor. To overcome this issue and allow the actuator to survive high speed suspension events, passive valving may be incorporated to act hydraulically in either parallel, in series, or combination of both, with the HSU. Such passive valving may include a diverter valve(s)  10 - 426 . The diverter valve(s)  10 - 426  is configured to activate at fluid flow rate (i.e. a fluid diversion threshold) and will divert hydraulic fluid away from the HSU  10 - 412  that is operatively connected to the hydraulic actuator in response to the hydraulic fluid flowing at a rate that exceeds the fluid diversion threshold. The fluid diversion threshold may be selected so that the maximum safe operating speed of the HSU and motor is never exceeded, even at very high speed suspension events. When the diverter activates and enters the diverted flow mode, restricting fluid flow to the hydraulic pump, a controlled split flow path is created so that fluid flow can by-pass the hydraulic pump in a controlled manner, thereby creating a damping force on the actuator so that wheel damping is achieved when the diverter valve is in the diverted flow mode. A diverter valve may be incorporated in at least one of the compression and extension stroke directions. The diverter valve(s) may located in the extension volume and compression volumes as shown in the embodiment of  FIG. 4  or elsewhere in the hydraulic connection between the actuator body  10 - 404  and the HSU  10 - 406 , and the disclosure is not limited in this regard. Other forms of passive valving may be incorporated to act hydraulically in either parallel, in series (or combination of both) with the HSU, such as a blow-off valve(s)  10 - 428 . The blow off valve(s) can be adapted so that can operate when a specific pressure drop across the piston  10 - 422  is achieved, thereby limiting the maximum pressure in the system. The blow off valve(s)  10 - 428  may located in the piston as shown in the embodiment of  FIG. 4  or elsewhere in the hydraulic connection between the actuator body  10 - 404  and the HSU  10 - 406 , and the disclosure is not limited in this regard. The passive valving used the active suspension actuator  10 - 402  can be adapted so as to provide a progressive actuation, thereby minimizing any NVH (noise, vibration, or harshness) induced by their operation. The passive valving that may be incorporated the in the active suspension actuator may comprise of at least one of progressive valving, multi-stage valving, flexible discs, disc stacks, amplitude dependent damping valves, volume variable chamber valving, baffle plate for defining a quieting duct for reducing noise related to fluid flow. Other forms of controlled valving may also be incorporated the in the active suspension actuator, such as proportional solenoid valving placed in series or in parallel with the HSU, electromagnetically adjustable valves for communicating hydraulic fluid between a piston-local chamber and a compensating chamber, and pressure control with adjustable limit valving. These types of arrangements and constructions of passive and controlled valving are well known in the art, and anyone skilled in the art could construct and adapt such arrangements, and as such the patent is not limited in this regard. 
     Since fluid volume in the actuator body  10 - 404  changes as the piston  10 - 424  enters and exits the actuator, the embodiment of  FIG. 4  includes an accumulator  10 - 434  to accept the piston rod volume. In one embodiment disclosed, the accumulator is a nitrogen-filled chamber with a floating piston  10 - 436  able to move in the actuator body and sealed from the hydraulic fluid with a seal  10 - 438 . In the embodiment shown the accumulator is in fluid communication with the compression chamber  10 - 416 . The nitrogen in the accumulator is at a pre-charge pressure, the value of which is determined so that it is at a higher value than the maximum working pressure in the compression chamber. The floating piston  10 - 436  rides in the bore of an accumulator body  10 - 440  that is rigidly connected to the actuator body  10 - 404 . A small annular gap  10 - 442  may exist between the outside of the accumulator body  10 - 440  and the actuator body  10 - 404  that is in fluid communication with the compression chamber, and hence is at the same pressure (or near same pressure) as the accumulator, thereby negating or reducing the pressure drop between the inside and outside of the accumulator body. This arrangement allows for the use a thin wall accumulator body, without the body dilating under pressure from the pre-charged nitrogen. 
     While an internal accumulator has been depicted, any appropriate structure, device, or compressible medium capable of accommodating a change in the fluid volume present within the actuator  10 - 404 , including an externally located accumulator, might be used, and while the accumulator is depicted being in fluid communication with the compression chamber, the accumulator could be in fluid communication with the extension chamber, as the disclosure is not so limited. 
     The compact nature and size of the electro-hydraulic actuator enables the electro-hydraulic actuator to be readily installed into a cabin stabilization application. 
       FIG. 5  shows an embodiment of an electro-hydraulic regenerative/active smart valve  10 - 502 , as disclosed in the embodiment of  FIG. 4 , comprising a fluid filled housing  10 - 504  coupled with the control housing  10 - 506 , wherein the control housing is integrated with the electro-hydraulic regenerative/active smart valve  10 - 502 . The smart valve assembly comprises a hydraulic pump/motor assembly (HSU)  10 - 508  closely coupled and operatively connected to a rotor  10 - 510  of an electric motor/generator, wherein the stator  10 - 512  of the electric motor/generator is rigidly located to the body of the smart valve assembly  10 - 502 . The HSU comprises of a first port  10 - 514  that is in fluid communication with a first chamber of the actuator and a second port  10 - 516  that is in fluid communication with a second chamber of the actuator, wherein the second port  10 - 516  is also in fluid communication with fluid  10 - 518  that is contained within the volume of the housing  10 - 504 . The HSU and electric motor/generator assembly is contained within and operates within the fluid  10 - 518  that is within the fluid filled housing  10 - 504 . For reasons of reliability and durability the electric motor/generator may be of the BLDC type (although other type of motor are anticipated), whereby electric commutation is carried out via the electronic controller and control protocols, as opposed to using mechanical means for commutation (such as brushes for example), which may not remain reliable in an oil filled environment. As the fluid  10 - 518  is in fluid communication with the second port  10 - 516  of the HSU  10 - 508 , any pressure that is present at the second port of the HSU will also be present in the fluid  10 - 518 . The fluid pressure at the second port may be generated by the pressure drop that exists across the HSU (and hence across the piston of the actuator of the embodiment of  FIG. 4 ) and may change accordingly with the pressure drop (and hence force) across the piston. The pressure at the second port may also be present due to a pre-charge pressure that may exist due to a pressurized reservoir (that may exist to account for the rod volume that is introduced or removed from the working volume of the actuator as the piston and piston rod strokes, for example). This pre-charge pressure may fluctuate with stroke position, with temperature or with a combination of both. The pressure at the second port may also be generated as a combination of the pressure drop across the HSU and the pre-charge pressure. 
     The control housing  10 - 506  is integrated with the smart valve body  10 - 502  and comprises a controller cavity  10 - 520 . The controller cavity  10 - 520  is separated from the hydraulic fluid  10 - 518  that is contained within the housing  10 - 504  by a bulkhead  10 - 522  whereby the pressure within controller cavity  10 - 520  is at atmospheric (or near atmospheric) pressure. The bulkhead  10 - 522  contains the fluid  10 - 518  within the fluid-filled housing  10 - 504 , by a seal(s)  10 - 524 , acting as a pressure barrier between the fluid-filled housing and the control cavity. The control housing  10 - 506  comprises a controller assembly  10 - 526  wherein, the electronic controller assembly may comprise of a logic board  10 - 528 , a power board  10 - 530 , and a capacitor  10 - 532  among other components. The controller assembly is rigidly connected to the control housing  10 - 506 . The electric motor/generator stator  10 - 512  comprises winding electrical terminations  10 - 534 , and these terminations are electrically connected to a flexible electrical connection (such as a flex PCB for example)  10 - 536  that is electrical communication with an electronic connector  10 - 538 . The electronic connector  10 - 538  passes through the bulkhead  10 - 522 , while containing the hydraulic fluid  10 - 518  that is in the fluid filled housing via a sealed pass-through  10 - 540 . 
     As the bulkhead  10 - 522  contains the fluid  10 - 518  within the fluid filled housing  10 - 504 , the bulkhead is subjected to the pressure of the fluid  10 - 518 , and hence the pressure of the second port  10 - 516  of the HSU, on the fluid side of the bulkhead, and the bulkhead is subjected to atmospheric (or near atmospheric) pressure on the controller cavity side of the bulkhead. This may create a pressure differential across the bulkhead which may cause the bulkhead to deflect. Even if the bulkhead is constructed from a strong and stiff material (such as steel for example), any change in the pressure differential between the fluid  10 - 518  and the controller cavity  10 - 520  may cause a change in the deflection of the bulkhead. As the sealed pass-through  10 - 540  passes through the bulkhead, any change in deflection of the bulkhead may impart a motion on the sealed pass-through, which may in turn impart a motion on the electronic connector  10 - 538 , that is contained within the sealed pass-through. The flexible electrical connection  10 - 536  is adapted so that it can absorb any motions that may exist between the electrical connector  10 - 538  and the winding electrical terminations  10 - 534  so that the connections between the winding electrical terminations  10 - 534  and the flexible electrical connection  10 - 536  and between flexible electrical connection  10 - 536  and the electronic connector  10 - 538  do not become fatigued over time which may cause these connections to fail. 
     The electrical connector  10 - 538  is in electrical connection with the power board  10 - 530  via another compliant electrical member (not shown). The compliant electrical member is adapted so that it can absorb any motions that may exist between the electrical connector  10 - 538  and the power board  10 - 530  so that the connections between the power board  10 - 530  and the compliant electrical member and between compliant electrical member and the electronic connector  10 - 538  do not become fatigued over time which may cause these connections to fail. 
     The control housing  10 - 506  comprises the control assembly  10 - 526  which may be comprised of a logic board, a power board, capacitors and other electronic components such as FETs or IGBTs. To offer an efficient means of heat dissipation for the control assembly  10 - 526 , the control housing  10 - 506  may act as a heat sink, and may be constructed from a material that offers good thermal conductivity and mass (such as an aluminum or heat dissipating plastic for example). To ensure that an efficient heat dissipating capability is achieved by the control housing  10 - 506 , the power components of the control assembly  10 - 526  (such as the FETs or IGBTs) may be mounted flat and in close contact with the inside surface of the control housing  10 - 506  so that it may utilize this surface as a heat sink. The construction of the control housing  10 - 506  may be such that the heat sink surface may be in thermal isolation from the fluid filled housing  10 - 504 , by constructing the housing from various materials by such methods as over-molding the heat sink surface material with a thermally nonconductive plastic that is in contact with the housing  10 - 504 . Or conversely the control housing  10 - 506  may be constructed so that the heat sink surface may be thermally connected to the fluid filled housing  10 - 504 . The heat sink feature of the control housing  10 - 506  may be adapted and optimized to use any ambient air flow that exists in the cabin installation to cool the thermal mass of the heat sink. 
     A rotary position sensor  10 - 542 , that measures the rotational position of a source magnet  10 - 544  that is drivingly connected to the electric motor/generator rotor  10 - 510 , is mounted directly to the logic board  10 - 528 . The rotary position sensor may be of a Hall effect type or other type. A non-magnetic sensor shield  10 - 546  is located within the bulkhead and lies in between the source magnet  10 - 544  and the rotary position sensor  10 - 542 , whereby the sensor shield contains the fluid  10 - 518  that is in the fluid filled housing while allowing the magnetic flux of the source magnet  10 - 544  to pass through unimpeded so that it can be detected by the rotary position sensor  10 - 542  so that it can detect the angular position of the rotor  10 - 510 . 
     The signal from the rotary position sensor  10 - 542  may be used by the electronic controller for commutation of the BLDC motor as well as for other functions such as for the use in a hydraulic ripple cancellation algorithm (or protocol); all positive displacement hydraulic pumps and motors (HSUs) produce a pressure pulsation that is in relation to its rotational position. This pressure pulsation is generated because the HSU does not supply an even flow per revolution, the HSU produces a flow pulsation per revolution, whereby at certain positions the HSU delivers more flow than its nominal theoretical flow per rev. (i.e. an additional flow) and at other position the HSU delivers less flow than its nominal theoretical flow per rev. (i.e. a negative flow). The profile of the flow pulsation (or ripple) is known with respect to the rotary position of the HSU. This flow ripple then in turn generates a pressure ripple in the system due to the inertia of the rotational components and the mass of the fluid etc. and this pressure pulsation can produce undesirable noise and force pulsations in downstream actuators etc. Since the profile of the pressure pulsation can be determined relative to the pump position, and hence the rotor and hence the source magnet position, it is possible for the controller to use a protocol that can vary the motor current and hence the motor torque based upon the rotor position signal to counteract these pressure pulsations, thereby mitigating or reducing the pressure pulsations and hence reducing the hydraulic noise and improving the performance of the system. Another method of reducing hydraulic ripple from the HSU may be in the use of a port timed accumulator buffer. In this arrangement the HSU comprises ports that are timed in accordance with the HSU flow ripple signature so that in positions when the HSU delivers more flow than its nominal (i.e. an additional flow) a port is opened from the HSU first port to a chamber that comprises a compressible medium so that there is fluid flow from the HSU to the chamber to accommodate this additional flow, and at positions when the HSU delivers less flow than its nominal (i.e. a negative flow) a port is opened from the HSU first port to the reservoir that comprises a compressible medium so that the fluid can flow from the reservoir to the HSU first port, to make up for the negative flow. The chamber with the compressible medium thereby buffers out the flow pulsations and hence the pressure pulsations from the HSU. It is possible to use the hydraulic ripple cancellation algorithm described earlier with the port timed accumulator buffer described above to further reduce the pressure ripple and noise signature of the HSU thereby further improving the performance of the smart valve.