Patent Publication Number: US-11028861-B2

Title: Hydraulic system and method for reducing boom bounce with counter-balance protection

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a Continuation of U.S. patent application Ser. No. 15/804,542, filed Nov. 6, 2017, now U.S. Pat. No. 10,502,239, which is a continuation of U.S. patent application Ser. No. 14/894,662 filed on Nov. 30, 2015, which is a National Stage Application of PCT/US2014/037879 filed on May 13, 2014, which claims benefit of U.S. Patent Application Ser. No. 61/829,796 filed on May 31, 2013, and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications. 
    
    
     BACKGROUND 
     Various off-road and on-road vehicles include booms. For example, certain concrete pump trucks include a boom configured to support a passage through which concrete is pumped from a base of the concrete pump truck to a location at a construction site where the concrete is needed. Such booms may be long and slender to facilitate pumping the concrete a substantial distance away from the concrete pump truck. In addition, such booms may be relatively heavy. The combination of the substantial length and mass properties of the boom may lead to the boom exhibiting undesirable dynamic behavior. In certain booms in certain configurations, a natural frequency of the boom may be about 0.3 Hertz (i.e., 3.3 seconds per cycle). In certain booms in certain configurations, the natural frequency of the boom may be less than about 1 Hertz (i.e., 1 second per cycle). In certain booms in certain configurations, the natural frequency of the boom may range from about 0.1 Hertz to about 1 Hertz (i.e., 10 seconds per cycle to 1 second per cycle). For example, as the boom is moved from place to place, the starting and stopping loads that actuate the boom may induce vibration (i.e., oscillation). Other load sources that may excite the boom include momentum of the concrete as it is pumped along the boom, starting and stopping the pumping of concrete along the boom, wind loads that may develop against the boom, and/or other miscellaneous loads. 
     Other vehicles with booms include fire trucks in which a ladder may be included on the boom, fire trucks which include a boom with plumbing to deliver water to a desired location, excavators which use a boom to move a shovel, tele-handlers which use a boom to deliver materials around a construction site, cranes which may use a boom to move material from place to place, etc. 
     In certain boom applications, including those mentioned above, a hydraulic cylinder may be used to actuate the boom. By actuating the hydraulic cylinder, the boom may be deployed and retracted, as desired, to achieve a desired placement of the boom. In certain applications, counter-balance valves may be used to control actuation of the hydraulic cylinder and/or to prevent the hydraulic cylinder from uncommanded movement (e.g., caused by a component failure). A prior art system  100 , including a first counter-balance valve  300  and a second counter-balance valve  400  is illustrated at  FIG. 1 . The counter-balance valve  300  controls and/or transfers hydraulic fluid flow into and out of a first chamber  116  of a hydraulic cylinder  110  of the system  100 . Likewise, the second counter-balance valve  400  controls and/or transfers hydraulic fluid flow into and out of a second chamber  118  of the hydraulic cylinder  110 . In particular, a port  302  of the counter-balance valve  300  is connected to a port  122  of the hydraulic cylinder  110 . Likewise, a port  402  of the counter-balance valve  400  is fluidly connected to a port  124  of the hydraulic cylinder  110 . As depicted, a fluid line  522  schematically connects the port  302  to the port  122 , and a fluid line  524  connects the port  402  to the port  124 . The counter-balance valves  300 ,  400  are typically mounted directly to the hydraulic cylinder  110 . The port  302  may directly connect to the port  122 , and the port  402  may directly connect to the port  124 . 
     The counter-balance valves  300 ,  400  provide safety protection to the system  100 . In particular, before movement of the cylinder  110  can occur, hydraulic pressure must be applied to both of the counter-balance valves  300 ,  400 . The hydraulic pressure applied to one of the counter-balance valves  300 ,  400  is delivered to a corresponding one of the ports  122 ,  124  of the hydraulic cylinder  110  thereby urging a piston  120  of the hydraulic cylinder  110  to move. The hydraulic pressure applied to an opposite one of the counter-balance valves  400 ,  300  allows hydraulic fluid to flow out of the opposite port  124 ,  122  of the hydraulic cylinder  110 . By requiring hydraulic pressure at the counter-balance valve  300 ,  400  corresponding to the port  122 ,  124  that is releasing the hydraulic fluid, a failure of a hydraulic line, a valve, a pump, etc. that supplies or receives the hydraulic fluid from the hydraulic cylinder  110  will not result in uncommanded movement of the hydraulic cylinder  110 . 
     Turning now to  FIG. 1 , the system  100  will be described in detail. As depicted, a four-way three position hydraulic control valve  200  is used to control the hydraulic cylinder  110 . The control valve  200  includes a spool  220  that may be positioned at a first configuration  222 , a second configuration  224 , or a third configuration  226 . As depicted at  FIG. 1 , the spool  220  is at the first configuration  222 . In the first configuration  222 , hydraulic fluid from a supply line  502  is transferred from a port  212  of the control valve  200  to a port  202  of the control valve  200  and ultimately to the port  122  and the chamber  116  of the hydraulic cylinder  110 . The hydraulic cylinder  110  is thereby urged to extend and hydraulic fluid in the chamber  118  of the hydraulic cylinder  110  is urged out of the port  124  of the cylinder  110 . Hydraulic fluid leaving the port  124  returns to a hydraulic tank by entering a port  204  of the control valve  200  and exiting a port  214  of the control valve  200  into a return line  504 . In certain embodiments, the supply line  502  supplies hydraulic fluid at a constant or at a near constant supply pressure. In certain embodiments, the return line  504  receives hydraulic fluid at a constant or at a near constant return pressure. 
     When the spool  220  is positioned at the second configuration  224 , hydraulic fluid flow between the port  202  and the port  212  and hydraulic fluid flow between the port  204  and the port  214  is effectively stopped, and hydraulic fluid flow to and from the cylinder  110  is effectively stopped. Thus, the hydraulic cylinder  110  remains substantially stationary when the spool  220  is positioned at the second configuration  224 . 
     When the spool  220  is positioned at the third configuration  226 , hydraulic fluid flow from the supply line  502  enters through the port  212  and exits through the port  204  of the valve  200 . The hydraulic fluid flow is ultimately delivered to the port  124  and the chamber  118  of the hydraulic cylinder  110  thereby urging retraction of the cylinder  110 . As hydraulic fluid pressure is applied to the chamber  118 , hydraulic fluid within the chamber  116  is urged to exit through the port  122 . Hydraulic fluid exiting the port  122  enters the port  202  and exits the port  214  of the valve  200  and thereby returns to the hydraulic tank. An operator and/or a control system may move the spool  220  as desired and thereby achieve extension, retraction, and/or locking of the hydraulic cylinder  110 . 
     A function of the counter-balance valves  300 ,  400  when the hydraulic cylinder  110  is extending will now be discussed in detail. Upon the spool  220  of the valve  200  being placed in the first configuration  222 , hydraulic fluid pressure from the supply line  502  pressurizes a hydraulic line  512 . The hydraulic line  512  is connected between the port  202  of the control valve  200 , a port  304  of the counter-balance valve  300 , and a port  406  of the counter-balance valve  400 . Hydraulic fluid pressure applied at the port  304  of the counter-balance valve  300  flows past a spool  310  of the counter-balance valve  300  and past a check valve  320  of the counter-balance valve  300  and thereby flows from the port  304  to the port  302  through a passage  322  of the counter-balance valve  300 . The hydraulic fluid pressure further flows through the port  122  and into the chamber  116  (i.e., a meter-in chamber). Pressure applied to the port  406  of the counter-balance valve  400  moves a spool  410  of the counter-balance valve  400  against a spring  412  and thereby compresses the spring  412 . Hydraulic fluid pressure applied at the port  406  thereby opens a passage  424  between the port  402  and the port  404 . By applying hydraulic pressure at the port  406 , hydraulic fluid may exit the chamber  118  (i.e., a meter-out chamber) through the port  124 , through the line  524 , through the passage  424  of the counter-balance valve  400  across the spool  410 , through a hydraulic line  514 , through the valve  200 , and through the return line  504  into the tank. The meter-out side may supply backpressure. 
     A function of the counter-balance valves  300 ,  400  when the hydraulic cylinder  110  is retracting will now be discussed in detail. Upon the spool  220  of the valve  200  being placed in the third configuration  226 , hydraulic fluid pressure from the supply line  502  pressurizes the hydraulic line  514 . The hydraulic line  514  is connected between the port  204  of the control valve  200 , a port  404  of the counter-balance valve  400 , and a port  306  of the counter-balance valve  300 . Hydraulic fluid pressure applied at the port  404  of the counter-balance valve  400  flows past the spool  410  of the counter-balance valve  400  and past a check valve  420  of the counter-balance valve  400  and thereby flows from the port  404  to the port  402  through a passage  422  of the counter-balance valve  400 . The hydraulic fluid pressure further flows through the port  124  and into the chamber  118  (i.e., a meter-in chamber). Hydraulic pressure applied to the port  306  of the counter-balance valve  300  moves the spool  310  of the counter-balance valve  300  against a spring  312  and thereby compresses the spring  312 . Hydraulic fluid pressure applied at the port  306  thereby opens a passage  324  between the port  302  and the port  304 . By applying hydraulic pressure at the port  306 , hydraulic fluid may exit the chamber  116  (i.e., a meter-out chamber) through the port  122 , through the line  522 , through the passage  324  of the counter-balance valve  300  across the spool  310 , through the hydraulic line  512 , through the valve  200 , and through the return line  504  into the tank. The meter-out side may supply backpressure. 
     The supply line  502 , the return line  504 , the hydraulic line  512 , the hydraulic line  514 , the hydraulic line  522 , and/or the hydraulic line  524  may belong to a line set  500 . 
     SUMMARY 
     One aspect of the present disclosure relates to systems and methods for reducing boom dynamics (e.g., boom bounce) of a boom while providing counter-balance valve protection to the boom. 
     Another aspect of the present disclosure relates to a hydraulic system including a hydraulic cylinder, a first counter-balance valve, a second counter-balance valve, a first control valve, a second control valve, and a selection valve arrangement. The hydraulic cylinder includes a first chamber and a second chamber. The first counter-balance valve fluidly connects to the first chamber at a first node, and the second counter-balance valve fluidly connects to the second chamber at a second node. The first control valve fluidly connects to the first counter-balance valve at a third node, and a second control valve fluidly connects to the second counter-balance valve at a fourth node. The selection valve arrangement is fluidly connected to the first node and the second node and is adapted to self-configure to a first configuration set when a net load is supported by the second chamber of the hydraulic cylinder and is further adapted to self-configure to a second configuration set when the net load is supported by the first chamber of the hydraulic cylinder. When the selection valve arrangement is enabled and at the first configuration set, the first control valve is adapted to fluctuate a first hydraulic fluid flow to the first chamber and thereby cause the hydraulic cylinder to produce a first vibratory response. 
     In certain embodiments, when the selection valve arrangement is enabled and at the second configuration set, the second control valve is adapted to fluctuate a second hydraulic fluid flow to the second chamber and thereby cause the hydraulic cylinder to produce a second vibratory response. In certain embodiments, the first chamber is a rod chamber and the second chamber is a head chamber. In other embodiments, the first chamber is a head chamber and the second chamber is a rod chamber. In certain embodiments, the first counter-balance valve, the second counter-balance valve, and the selection valve arrangement are physically mounted to the hydraulic cylinder. 
     Still another aspect of the present disclosure relates to a hydraulic valve set including a first counter-balance valve, a second counter-balance valve, and a selection valve arrangement. The first counter-balance valve provides a first back-flow protection to a first node. The first counter-balance valve includes a first counter-balance valve opening node. The second counter-balance valve provides a second back-flow protection to a second node. The second counter-balance valve includes a second counter-balance valve opening node. The selection valve arrangement is fluidly connected to the first node, the second node, the first counter-balance valve opening node, and the second counter-balance valve opening node. The selection valve arrangement is adapted to self-configure in response to a net spool force produced by a first fluid pressure of the first node and a second fluid pressure of the second node. When the net spool force is in a first direction, the selection valve arrangement connects the first node of the first counter-balance valve to the second counter-balance valve opening node of the second counter-balance valve. When the net spool force is in a second direction, the selection valve arrangement connects the second node of the second counter-balance valve to the first counter-balance valve opening node of the first counter-balance valve. 
     Yet another aspect of the present disclosure relates to a hydraulic boom control system including a pair of counter-balance valves, a selection valve arrangement, and a pair of control valves. The pair of counter-balance valves is hydraulically coupled to opposite sides of a hydraulic actuator of a boom. The selection valve arrangement senses a net unloaded side of the opposite sides of the hydraulic actuator and opens a one of the pair of counter-balance valves corresponding to the net unloaded side. The pair of control valves corresponds to the opposite sides of the hydraulic actuator. A one of the pair of control valves corresponds to the net unloaded side and transmits a vibratory hydraulic fluid flow to the net unloaded side of the hydraulic actuator. 
     Still another aspect of the present disclosure relates to a method of controlling vibration in a boom. The method includes: 1) providing a valve arrangement that includes a pair of counter-balance valves, a pair of control valves, and a selector valve set; 2) providing a hydraulic actuator that includes a pair of chambers; 3) configuring the selector valve set with a net load that is applied on the hydraulic actuator and thereby configures the pair of counter-balance valves; 4) locking a loaded chamber of the pair of chambers with a respective one of the pair of counter-balance valves that has been configured by the configuring of the pair of counter-balance valves; and 5) transmitting vibrating hydraulic fluid with a respective one of the pair of control valves to an unloaded chamber of the pair of chambers. 
     A variety of additional aspects will be set forth in the description that follows. These aspects can relate to individual features and to combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad concepts upon which the embodiments disclosed herein are based. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a prior art hydraulic system including a hydraulic cylinder with a pair of counter-balance valves and a control valve; 
         FIG. 2  is a schematic illustration of a hydraulic system including the hydraulic cylinder and the counter-balance valves of  FIG. 1  configured with a hydraulic cylinder control system according to the principles of the present disclosure; 
         FIG. 3  is an enlarged portion of  FIG. 2 ; 
         FIG. 4  is a schematic illustration of a hydraulic cylinder suitable for use with the hydraulic cylinder control system of  FIG. 2  according to the principles of the present disclosure; 
         FIG. 5  is a schematic illustration of a vehicle with a boom system that is actuated by one or more cylinders and controlled with the hydraulic system of  FIG. 2  according to the principles of the present disclosure; and 
         FIG. 6  is a flow chart illustrating an example method for controlling a cylinder used to position a boom, such as the hydraulic cylinder of  FIG. 4 , according to the principles of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     According to the principles of the present disclosure, a hydraulic system is adapted to actuate the hydraulic cylinder  110 , including the counter-balance valves  300  and  400 , and further provide means for counteracting vibrations to which the hydraulic cylinder  110  is exposed. As illustrated at  FIG. 2 , an example system  600  is illustrated with the hydraulic cylinder  110  (i.e., a hydraulic actuator), the counter-balance valve  300 , and the counter-balance valve  400 . The hydraulic cylinder  110  and the counter-balance valves  300 ,  400  of  FIG. 2  may be the same as those shown in the prior art system  100  of  FIG. 1 . The hydraulic system  600  may therefore be retrofitted to an existing and/or a conventional hydraulic system. Certain features of the hydraulic cylinder  110  and the counter-balance valves  300 ,  400  will not be redundantly re-described. 
     According to the principles of the present disclosure, similar protection is provided by the counter-balance valves  300 ,  400  for the hydraulic cylinder  110  and the hydraulic system  600 , as described above with respect to the hydraulic system  100 . In particular, failure of a hydraulic line, a hydraulic valve, and/or a hydraulic pump will not lead to an uncommanded movement of the hydraulic cylinder  110  of the hydraulic system  600 . The hydraulic architecture of the hydraulic system  600  further provides the ability to counteract vibrations using the hydraulic cylinder  110 . 
     The hydraulic cylinder  110  may hold a net load  90  that, in general, may urge retraction or extension of a rod  126  of the cylinder  110 . The rod  126  is connected to the piston  120  of the cylinder  110 . If the load  90  urges extension of the hydraulic cylinder  110 , the chamber  118  on a rod side  114  of the hydraulic cylinder  110  is pressurized by the load  90 , and the counter-balance valve  400  acts to prevent the release of hydraulic fluid from the chamber  118  and thereby acts as a safety device to prevent uncommanded extension of the hydraulic cylinder  110 . In other words, the counter-balance valve  400  locks the chamber  118 . In addition to providing safety, the locking of the chamber  118  prevents drifting of the cylinder  110 . Vibration control may be provided via the hydraulic cylinder  110  by dynamically pressurizing and depressurizing the chamber  116  on a head side  112  of the hydraulic cylinder  110 . As the hydraulic cylinder  110 , the structure to which the hydraulic cylinder  110  is attached, and the hydraulic fluid within the chamber  118  are at least slightly deformable, selective application of hydraulic pressure to the chamber  116  will cause movement (e.g., slight movement) of the hydraulic cylinder  110 . Such movement, when timed in conjunction with a system model and dynamic measurements of the system, may be used to counteract vibrations of the system. 
     If the load  90  urges retraction of the hydraulic cylinder  110 , the chamber  116  on the head side  112  of the hydraulic cylinder  110  is pressurized by the load  90 , and the counter-balance valve  300  acts to prevent the release of hydraulic fluid from the chamber  116  and thereby acts as a safety device to prevent uncommanded retraction of the hydraulic cylinder  110 . In other words, the counter-balance valve  300  locks the chamber  116 . In addition to providing safety, the locking of the chamber  116  prevents drifting of the cylinder  110 . Vibration control may be provided via the hydraulic cylinder  110  by dynamically pressurizing and depressurizing the chamber  118  on the rod side  114  of the hydraulic cylinder  110 . As the hydraulic cylinder  110 , the structure to which the hydraulic cylinder  110  is attached, and the hydraulic fluid within the chamber  116  are at least slightly deformable, selective application of hydraulic pressure to the chamber  118  will cause movement (e.g., slight movement) of the hydraulic cylinder  110 . Such movement, when timed in conjunction with the system model and dynamic measurements of the system, may be used to counteract vibrations of the system. 
     The load  90  is depicted as attached via a rod connection  128  to the rod  126  of the cylinder  110 . In certain embodiments, the load  90  is a tensile or a compressive load across the rod connection  128  and the head side  112  of the cylinder  110 . 
     As is further described below, the system  600  provides a control framework and a control mechanism to achieve boom vibration reduction for both off-highway vehicles and on-highway vehicles. The vibration reduction may be adapted to reduced vibrations in booms with relatively low natural frequencies (e.g., the concrete pump truck boom). The hydraulic system  600  may also be applied to booms with relatively high natural frequencies (e.g., an excavator boom). Compared with conventional solutions, the hydraulic system  600  achieves vibration reduction of booms with fewer sensors and a simplified control structure. The vibration reduction method may be implemented while assuring protection from failures of certain hydraulic lines, hydraulic valves, and/or hydraulic pumps, as described above. The protection from failure may be automatic and/or mechanical. In certain embodiments, the protection from failure may not require any electrical signal and/or electrical power to engage. The protection from failure may be a regulatory requirement (e.g., an ISO standard). The regulatory requirement may require certain mechanical means of protection that is provided by the hydraulic system  600 . 
     Certain booms may include stiffness and inertial properties that can transmit and/or amplify dynamic behavior of the load  90 . As the dynamic load  90  may include external force/position disturbances that are applied to the boom, severe vibrations (i.e., oscillations) may result especially when these disturbances are near the natural frequency of the boom. Such excitation of the boom by the load  90  may result in safety issues and/or decrease productivity and/or reliability of the boom system. By measuring parameters of the hydraulic system  600  and responding appropriately, effects of the disturbances may be reduced and/or minimized or even eliminated. The response provided may be effective over a wide variety of operating conditions. According to the principles of the present disclosure, vibration control may be achieved using minimal numbers of sensors. 
     According to the principles of the present disclosure, hydraulic fluid flow to the chamber  116  of the head  112  side of the cylinder  110 , and hydraulic fluid flow to the chamber  118  of the rod side  114  of the cylinder  110  are independently controlled and/or metered to realize boom vibration reduction and also to prevent the cylinder  110  from drifting. According to the principles of the present disclosure, the hydraulic system  600  may be configured similar to a conventional counter-balance system (e.g., the hydraulic system  100 ). 
     In certain embodiments, the hydraulic system  600  is configured to the conventional counter-balance configuration when a movement of the cylinder  110  is commanded. As further described below, the hydraulic system  600  enables measurement of pressures within the chambers  116  and/or  118  of the cylinder  110  at a remote location away from the hydraulic cylinder  110  (e.g., at sensors  610 ). This architecture thereby may reduce mass that would otherwise be positioned on the boom and/or may simplify routing of hydraulic lines (e.g., hard tubing and hoses). Performance of machines such as concrete pump booms and/or lift handlers may be improved by such simplified hydraulic line routing and/or reduced mass on the boom. 
     The counter-balance valves  300  and  400  may be components of a valve arrangement  840 . The valve arrangement  840  may include various hydraulic components that control and/or regulate hydraulic fluid flow to and/or from the hydraulic cylinder  110 . The valve arrangement  840  may further include a control valve  700  (e.g., a proportional hydraulic valve), a control valve  800  (e.g., a proportional hydraulic valve), and a selector valve arrangement  850 , described in detail below. The control valves  700  and/or  800  may be high bandwidth and/or high resolution control valves. 
     In the depicted embodiment of  FIG. 2 , a node  51  is defined at the port  302  of the counter-balance valve  300  and the port  122  of the hydraulic cylinder  110 ; a node  52  is defined at the port  402  of the counter-balance valve  400  and the port  124  of the hydraulic cylinder  110 ; a node  53  is defined at the port  304  of the counter-balance valve  300  and the port  702  of the hydraulic valve  700 ; a node  54  is defined at the port  404  of the counter-balance valve  400  and the port  804  of the hydraulic valve  800 ; a node  55  is defined at the port  306  of the counter-balance valve  300  and a port  352  of a hydraulic valve  350 ; and a node  56  is defined at the port  406  of the counter-balance valve  400  and a port  452  of a hydraulic valve  450 . The hydraulic valves  350  and  450  are described in detail below. 
     Turning now to  FIG. 4 , the hydraulic cylinder  110  is illustrated with valve blocks  152 ,  154 . The valve blocks  152 ,  154  may be separate from each other, as illustrated, or may be a single combined valve block. The valve block  152  may be mounted to and/or over the port  122  of the hydraulic cylinder  110 , and the valve block  154  may be mounted to and/or over the port  124  of the hydraulic cylinder  110 . The valve blocks  152 ,  154  may be directly mounted to the hydraulic cylinder  110 . The valve block  152  may include the counter-balance valve  300 , and the valve block  154  may include the counter-balance valve  400 . The valve blocks  152  and/or  154  may include additional components of the valve arrangement  840 . The valve blocks  152 ,  154 , and/or the single combined valve block may include the selector valve arrangement  850  and/or components thereof. 
     Turning now to  FIG. 5 , an example boom system  10  is described and illustrated in detail. The boom system  10  may include a vehicle  20  and a boom  30 . The vehicle  20  may include a drive train  22  (e.g., including wheels and/or tracks). As depicted at  FIG. 5 , rigid retractable supports  24  are further provided on the vehicle  20 . The rigid supports  24  may include feet that are extended to contact the ground and thereby support and/or stabilize the vehicle  20  by bypassing ground support away from the drive train  22  and/or suspension of the vehicle  20 . In other vehicles (e.g., vehicles with tracks, vehicles with no suspension), the drive train  22  may be sufficiently rigid and retractable rigid supports  24  may not be needed and/or provided. 
     As depicted at  FIG. 5 , the boom  30  extends from a first end  32  to a second end  34 . As depicted, the first end  32  is rotatably attached (e.g., by a turntable) to the vehicle  20 . The second end  34  may be positioned by actuation of the boom  30  and thereby be positioned as desired. In certain applications, it may be desired to extend the second end  34  a substantial distance away from the vehicle  20  in a primarily horizontal direction. In other embodiments, it may be desired to position the second end  34  vertically above the vehicle  20  a substantial distance. In still other applications, the second end  34  of the boom  30  may be spaced both vertically and horizontally from the vehicle  20 . In certain applications, the second end  34  of the boom  30  may be lowered into a hole and thereby be positioned at an elevation below the vehicle  20 . 
     As depicted, the boom  30  includes a plurality of boom segments  36 . Adjacent pairs of the boom segments  36  may be connected to each other by a corresponding joint  38 . As depicted, a first boom segment  36   1  is rotatably attached to the vehicle  20  at a first joint  38   1 . The first boom segment  36   1  may be mounted by two rotatable joints. For example, the first rotatable joint may include a turntable, and the second rotatable joint may include a horizontal axis. A second boom segment  36   2  is attached to the first boom segment  36   1  at a second joint  38   2 . Likewise, a third boom segment  36   3  is attached to the second boom segment  36   2  at a joint  38   3 , and a fourth boom segment  36   4  is attached to the third boom segment  36   3  at a fourth joint  38   4 . A relative position/orientation between the adjacent pairs of the boom segments  36  may be controlled by a corresponding hydraulic cylinder  110 . For example, a relative position/orientation between the first boom segment  36   1  and the vehicle  20  is controlled by a first hydraulic cylinder  110   1 . The relative position/orientation between the first boom segment  36   1  and the second boom segment  36   2  is controlled by a second hydraulic cylinder  110   2 . Likewise, the relative position/orientation between the third boom segment  36   3  and the second boom segment  36   2  may be controlled by a third hydraulic cylinder  110   3 , and the relative position/orientation between the fourth boom segment  36   4  and the third boom segment  36   3  may be controlled by a fourth hydraulic cylinder  110   4 . 
     According to the principles of the present disclosure, the boom  30 , including the plurality of boom segments  36   1-4 , may be modeled and vibration of the boom  30  may be controlled by a controller  640 . In particular, the controller  640  may send a signal  652  to the valve  700  and a signal  654  to the valve  800 . The signal  652  may include a vibration component  652   v , and the signal  654  may include a vibration component  654   v . The vibration component  652   v ,  654   v  may cause the respective valve  700 ,  800  to produce a vibratory flow and/or a vibratory pressure at the respective port  702 ,  804 . The vibratory flow and/or the vibratory pressure may be transferred through the respective counter-balance valve  300 ,  400  and to the respective chamber  116 ,  118  of the hydraulic cylinder  110 . 
     The signals  652 ,  654  of the controller  640  may also include move signals that cause the hydraulic cylinder  110  to extend and retract, respectively, and thereby actuate the boom  30 . As depicted at  FIG. 3 , the controller also sends an enable signal  642  to the selector valve arrangement  850 . As shown, the enable signal  642  is transmitted to an enabler  630  which, in turn, sends a valve signal  632  to each of the valves  350  and  450 . Upon receiving the valve signal  632 , the valves  350  and  450  enable the selector valve arrangement  850 . Upon enablement, the selector valve arrangement  850  selects one of the counter-balance valves  300 ,  400  as a holding counter-balance valve and selects the other of the counter-balance valves  400 ,  300  as a vibration flow/pressure transferring counter-balance valve. In the depicted embodiment, a loaded one of the chambers  116 ,  118  of the hydraulic cylinder  110 , that is loaded by the net load  90 , corresponds to the holding counter-balance valve  300 ,  400 , and an unloaded one of the chambers  118 ,  116  of the hydraulic cylinder  110 , that is not loaded by the net load  90 , corresponds to the vibration flow/pressure transferring counter-balance valve  400 ,  300 . In certain embodiments, the vibration component  652   v  or  654   v  may be transmitted to the control valve  800 ,  700  that corresponds to the unloaded one of the chambers  118 ,  116  of the hydraulic cylinder  110 . 
     The controller  640  may receive input from various sensors, including the sensors  610 , position sensors, LVDTs, vision base sensors, etc. and thereby compute the signals  652 ,  654 , including the vibration component  652   v ,  654   v . The controller  640  may include a dynamic model of the boom  30  and use the dynamic model and the input from the various sensors to calculate the signals  652 ,  654 , including the vibration component  652   v ,  654   v . In certain embodiments, the enable signal  642  is transmitted directly to the valves  350  and  450  from the controller  640 . 
     In certain embodiments, a single system such as the hydraulic system  600  may be used on one of the hydraulic cylinders  110  (e.g., the hydraulic cylinder  110   1 ). In other embodiments, a plurality of the hydraulic cylinders  110  may each be actuated by a corresponding hydraulic system  600 . In still other embodiments, all of the hydraulic cylinders  110  may each be actuated by a system such as the system  600 . 
     As illustrated at  FIG. 2 , the example hydraulic system  600  includes the proportional hydraulic control valve  700  and the proportional hydraulic control valve  800 . The example hydraulic system  600  further includes the hydraulic valve  350 , the hydraulic valve  450 , and a hydraulic valve  900 . As depicted, the selector valve arrangement  850  includes the hydraulic valve  350 , the hydraulic valve  450 , and the hydraulic valve  900 . In the example embodiment, the hydraulic valves  700  and  800  are three-way three position proportional valves, the valves  350  and  450  are two-way two position valves, and the valve  900  is a four-way two position valve. The valves  700  and  800  may be combined within a common valve body. In certain embodiments, some or all of the valves  300 ,  350 ,  400 ,  450 ,  700 ,  800 , and/or  900  of the hydraulic system  600  may be combined within a common valve body and/or a common valve block. In certain embodiments, some or all of the valves  300 ,  350 ,  400 ,  450 ,  700 ,  800 , and/or  900  of the valve arrangement  840  may be combined within a common valve body and/or a common valve block. In certain embodiments, some or all of the valves  300 ,  350 ,  400 ,  450 , and/or  900  of the valve arrangement  840  may be combined within a common valve body and/or a common valve block. In certain embodiments, some or all of the valves  350 ,  450 , and/or  900  of the selector valve arrangement  850  may be combined within a common valve body and/or a common valve block. 
     Turning now to  FIG. 2 , certain elements of the hydraulic system  600  will be described in detail. The hydraulic valve  700  includes a spool  720  with a first configuration  722 , a second configuration  724 , and a third configuration  726 . As illustrated, the spool  720  is at the third configuration  726 . The valve  700  includes a port  702 , a port  712 , and a port  714 . In the first configuration  722 , the port  714  is blocked off, and the port  702  is fluidly connected to the port  712 . In the second configuration  724 , the ports  702 ,  712 ,  714  are all blocked off. In the third configuration  726 , the port  702  is fluidly connected to the port  714 , and the port  712  is blocked off. 
     The hydraulic valve  800  includes a spool  820  with a first configuration  822 , a second configuration  824 , and a third configuration  826 . As illustrated, the spool  820  is at the third configuration  826 . The valve  800  includes a port  804 , a port  812 , and a port  814 . In the first configuration  822 , the port  812  is blocked off, and the port  804  is fluidly connected to the port  814 . In the second configuration  824 , the ports  804 ,  812 ,  814  are all blocked off. In the third configuration  826 , the port  804  is fluidly connected to the port  812 , and the port  814  is blocked off. 
     In the depicted embodiment, a hydraulic line  562  connects the port  302  of the counter-balance valve  300  with the port  122  of the hydraulic cylinder  110  and with a port  902  of the valve  900 . The hydraulic line  562  may include a hydraulic line  572  that extends to a control port  932  of the valve  900 . The hydraulic line  572  may be a capillary line and have a delayed pressure response from the hydraulic line  562 . Node  51  may include the hydraulic line  562 . A hydraulic line  564  may connect the port  402  of the counter-balance valve  400  with the port  124  of the hydraulic cylinder  110  and with a port  914  of the valve  900 . The hydraulic line  564  may include a hydraulic line  574  that extends to a control port  934  of the valve  900 . The hydraulic line  574  may be a capillary line and have a delayed pressure response from the hydraulic line  564 . Node  52  may include the hydraulic line  564 . In certain embodiments, the hydraulic lines  562 ,  564  are included in valve blocks, housings, etc. and may be short in length. A hydraulic line  552  may connect the port  304  of the counter-balance valve  300  with the port  702  of the hydraulic valve  700  and with a port  462  of the valve  450 . Node  53  may include the hydraulic line  552 . Likewise, a hydraulic line  554  connects the port  404  of the counter-balance valve  400  with the port  804  of the valve  800  and with a port  362  of the valve  350 . Node  54  may include the hydraulic line  554 . 
     Sensors that measure temperature and/or pressure at various ports of the valves  700 ,  800  may be provided. In particular, a sensor  610   1  is provided adjacent the port  702  of the valve  700 . As depicted, the sensor  610   1  is a pressure sensor and may be used to provide dynamic information about the system  600  and/or the boom system  10 . As depicted at  FIG. 2 , a second sensor  610   2  is provided adjacent the port  804  of the hydraulic valve  800 . The sensor  610   2  may be a pressure sensor and may be used to provide dynamic information about the hydraulic system  600  and/or the boom system  10 . As further depicted at  FIG. 2 , a third sensor  610   3  may be provided adjacent the port  814  of the valve  800 , and a fourth sensor  610   4  may be provided adjacent the port  812  of the valve  800 . 
     In certain embodiments, pressure within the supply line  502  and/or pressure within the tank line  504  are well known, and the pressure sensors  610   1  and  610   2  may be used to calculate flow rates through the valves  700  and  800 , respectively. In other embodiments, a pressure difference across the valve  700 ,  800  is calculated. For example, the pressure sensor  610   3  and the pressure sensor  610   2  may be used when the spool  820  of the valve  800  is at the first position  822  and thereby calculate flow through the valve  800 . Likewise, a pressure difference may be calculated between the sensor  610   2  and the sensor  610   4  when the spool  820  of the valve  800  is at the third configuration  826 . The controller  640  may use these pressures and pressure differences as control inputs. 
     Temperature sensors may further be provided at and around the valves  700 ,  800  and thereby refine the flow measurements by allowing calculation of the viscosity and/or density of the hydraulic fluid flowing through the valves  700 ,  800 . The controller  640  may use these temperatures as control inputs. 
     Although depicted with the first sensor  610   1 , the second sensor  610   2 , the third sensor  610   3 , and the fourth sensor  610   4 , fewer sensors or more sensors than those illustrated may be used in alternative embodiments. Further, such sensors may be positioned at various other locations in other embodiments. In certain embodiments, the sensors  610  may be positioned within a common valve body. In certain embodiments, an Ultronics® servo valve available from Eaton Corporation may be used. The Ultronics® servo valve provides a compact and high performance valve package that includes two three-way valves (i.e., the valves  700  and  800 ), the pressure sensors  610 , and a pressure regulation controller. The Eaton Ultronics® servo valve further includes linear variable differential transformers (LVDT) that monitor positions of the spools  720 ,  820 , respectively. By using the two three-way proportional valves  700 ,  800 , the pressures of the chambers  116  and  118  may be independently controlled. In addition, the flow rates into and/or out of the chambers  116  and  118  may be independently controlled. In other embodiments, the pressure of one of the chambers  116 ,  118  may be independently controlled with respect to a flow rate into and/or out of the opposite chambers  116 ,  118 . 
     In comparison with using a single four-way proportional valve  200  (see  FIG. 1 ), the configuration of the hydraulic system  600  can achieve and accommodate more flexible control strategies with less energy consumption. For example, when the cylinder  110  is moving, the valve  700 ,  800  connected with the metered-out chamber  116 ,  118  can manipulate the chamber pressure while the valves  800 ,  700  connected with the metered-in chamber can regulate the flow entering the chamber  118 ,  116 . As the metered-out chamber pressure is not coupled with the metered-in chamber flow, the metered-out chamber pressure can be regulated to be low and thereby reduce associated throttling losses. 
     Turning again to  FIG. 3 , the valves  350 ,  450 , and  900  will be described in detail. The valve  350  is a two-way two position valve. In particular, the valve  350  includes the first port  352 , the second port  362 , and a third port  364 . The valve  350  includes a spool  370  with a first configuration  372  and a second configuration  374 . In the first configuration  372  (depicted at  FIG. 3 ), the port  352  and the port  362  are connected, and the port  364  is blocked. In the configuration  374 , the port  364  and the port  352  are connected and the port  362  is blocked. As depicted, the valve  350  includes a solenoid  376  and a spring  378 . The solenoid  376  and the spring  378  can be used to move the spool  370  between the first configuration  372  and the second configuration  374 . 
     The valve  450  is also a two-way two position valve. In particular, the valve  450  includes the first port  452 , the second port  462 , and a third port  464 . The valve  450  includes a spool  470  with a first configuration  472  and a second configuration  474 . In the first configuration  472  (also depicted at  FIG. 3 ), the port  452  and the port  462  are connected, and the port  464  is blocked. In the configuration  474 , the port  464  and the port  452  are connected and the port  462  is blocked. As depicted, the valve  470  includes a solenoid  476  and a spring  478 . The solenoid  476  and the spring  478  can be used to move the spool  470  between the first configuration  472  and the second configuration  474 . 
     The valve  900  is a four-way two position valve. In particular, the valve  900  includes the first port  902 , a second port  904 , a third port  912 , and the fourth port  914 . The valve  900  includes a spool  920  that may be configured in a first configuration  922  (depicted at  FIG. 3 ) and a second configuration  924 . In the first configuration, the ports  904  and  914  are connected, and the ports  902  and  912  are blocked. In the second configuration  924 , the ports  902  and  912  are connected, and the ports  904  and  914  are blocked. The spool  920  of the valve  900  is moved by a combination of springs  926  and  928  and pressure applied at the first control port  932  and the second control port  934 . 
     When the pressure is applied to the control port  932 , the spring  926  is compressed, and the spool  920  is urged toward the configuration  924 . Likewise, when the pressure is applied to the control port  934 , the spring  928  is compressed, and the spool  920  is urged toward the configuration  922 . Pressure applied to the port  932  acts on an area  936 . Likewise, pressure applied at the port  934  acts on an area  938 . As an area  132  (e.g., a head side area) acted on by pressure within the chamber  116  may be different than an area  134  (e.g., a rod side area) acted on by pressure in the chamber  118 , the areas  936 ,  938  may also be different and thereby compensate for the area differences between the head side  112  and the rod side  114  of the cylinder  110 . 
     To prevent excessive shuttling of the valve  900  when the net load  90  is light, a dead-band may be defined by the valve  900 . In certain embodiments, a hysteresis of the springs  926  and/or  928  ranges from about 10% to about 20% of a maximum full scale load. The maximum full scale load may be defined when either the chamber  116  or the chamber  118  is at its maximum holding capacity and supplies a corresponding pressure to the valve  900 . 
     The valve  350  is connected to the fluid line  554  at the port  362 . Likewise, the valve  450  is connected to the fluid line  552  at the port  462 . A fluid line  582  connects the port  364  of the valve  350  to the port  904  of the valve  900 . A node  57  may include the fluid line  582 . Likewise, a fluid line  584  connects the port  464  of the valve  450  to the port  912  of the valve  900 . A node  58  may include the fluid line  584 . The fluid line  562  further connects to the port  902  of the valve  900 . Likewise, the fluid line  564  further connects to the port  914  of the valve  900 . As depicted at  FIG. 3 , the fluid line  574  extends from the fluid line  564  and connects to the port  934 . The fluid line  574  may be at substantially a same pressure as the fluid line  564 . In other embodiments, the fluid line  574  may be a capillary line or have other flow restriction such as an orifice. The pressure at the port  934  may thereby be different from the pressure in the fluid line  564 , at least instantaneously different. Likewise, the fluid line  572  extends from the fluid line  562  and connects to the port  932 . The fluid line  572  may be at substantially a same pressure as the fluid line  562 . In other embodiments, the fluid line  572  may be a capillary line or have other flow restriction such as an orifice. The pressure at the port  932  may thereby be different from the pressure in the fluid line  562 , at least instantaneously different. 
     The supply line  502 , the return line  504 , the hydraulic line  552 , the hydraulic line  554 , the hydraulic line  562 , the hydraulic line  564 , the hydraulic line  572 , the hydraulic line  574 , the hydraulic line  582 , and/or the hydraulic line  584  may belong to a line set  550 . 
     Turning now to  FIGS. 2 and 3 , the operation of the selector valve arrangement  850  will be described in detail. As mentioned above, the controller  640  sends a signal to the enabler  630  which, in turn, sends a signal to the valves  350  and  450 . In certain embodiments, the signal sent to the valves  350  and  450  is synchronized and sent simultaneously to both of the valves  350  and  450 . Upon the signal to the valves  350 ,  450  being a disabled signal, the selector valve arrangement  850  configures the valve arrangement  840  in a conventional counter-balance arrangement. The conventional counter-balance arrangement may be engaged when moving the boom  30  under move commands to the control valves  700 ,  800 . In the disabled configuration, the valve  900  of the selector valve arrangement  850  may still sense the pressures in the first chamber  116  and the second chamber  118 . The valve  900  may thereby continue to shuttle between the first configuration  922  and the second configuration  924 , even when the selector valve arrangement  850  is disabled. 
     When the controller  640  sends an enable signal to the enabler  630 , and the enabler  630  sends an enable signal to the valves  350 ,  450 , the valve  350  moves to the second configuration  374 , and the valve  450  moves to the second configuration  474 . In certain embodiments, in the enabled configuration, the valve arrangement  840  effectively locks the hydraulic cylinder  110  from moving. In particular, regardless of the position of the valve  900 , one of the valves  350  or  450  will not receive high pressure and therefore will not transmit the high pressure to the corresponding counter-balance valve  300 ,  400 . As mentioned above, the enabled configuration of the selector valve arrangement  850  may be used to lock one of the chambers  116 ,  118  of the hydraulic cylinder  110  while sending vibratory pressure to an opposite one of the chambers  118 ,  116 . The vibratory pressure may be used to counteract external vibrations encountered by the boom  30 . 
     When the net load  90  is carried by the chamber  118 , pressure from the chamber  118  is applied at the port  934  of the valve  900  and urges the valve  900  toward the first configuration  922 . In the first configuration  922 , the port  904  and the port  914  of the valve  900  are connected and thereby connect the node  52  with the node  57 . As the valve  350  is enabled, and in the second configuration  374 , the nodes  52  and  57  are further connected to the node  55 . A passage for the high pressure fluid from the chamber  118  is thereby opened to the port  306  of the counter-balance valve  300 . The counter-balance valve  300  is thereby opened for bi-directional flow between the ports  302  and  304 . Opening up the counter-balance valve  300  to bi-directional flow allows the control valve  700  to apply and release hydraulic fluid pressure from the chamber  116  under the control of the controller  640 . 
     When the net load  90  is carried by the chamber  116 , pressure from the chamber  116  is applied at the port  932  of the valve  900  and urges the valve  900  toward the second configuration  924 . In the second configuration  924 , the port  902  and the port  912  of the valve  900  are connected and thereby connect the node  51  with the node  58 . As the valve  450  is enabled, and in the second configuration  474 , the nodes  51  and  58  are further connected to the node  56 . A passage for the high pressure fluid from the chamber  116  is thereby opened to the port  406  of the counter-balance valve  400 . The counter-balance valve  400  is thereby opened for bi-directional flow between the ports  402  and  404 . Opening up the counter-balance valve  400  to bi-directional flow allows the control valve  800  to apply and release hydraulic fluid pressure from the chamber  118  under the control of the controller  640 . 
     As schematically illustrated at  FIG. 2 , an environmental vibration load  960  is imposed as a component of the net load  90  on the hydraulic cylinder  110 . As depicted at  FIG. 2 , the vibration load component  960  does not include a steady state load component. In certain applications, the vibration load  960  includes dynamic loads such as wind loads, momentum loads of material that may be moved along the boom  30 , inertial loads from moving the vehicle  20 , and/or other dynamic loads. The steady state load may include gravity loads that may vary depending on the configuration of the boom  30 . The vibration load  960  may be sensed and estimated/measured by the various sensors  610  and/or other sensors. The controller  640  may process these inputs and use a model of the dynamic behavior of the boom system  10  and thereby calculate and transmit an appropriate vibration signal  652   v ,  654   v . The signal  652   v ,  654   v  is transformed into hydraulic pressure and/or hydraulic flow at the corresponding valve  700 ,  800 . The vibratory pressure/flow is transferred through the corresponding counter-balance valve  300 ,  400  and to the corresponding chamber  116 ,  118  of the hydraulic cylinder  110 . The hydraulic cylinder  110  transforms the vibratory pressure and/or the vibratory flow into a vibratory response force/displacement  950 . When the vibratory response  950  and the vibration load  960  are superimposed on the boom  30 , a resultant vibration  970  is produced. The resultant vibration  970  may be substantially less than a vibration of the boom  30  generated without the vibratory response  950 . Vibration of the boom  30  may thereby be controlled and/or reduced enhancing the performance, durability, safety, usability, etc. of the boom system  10 . The vibratory response  950  of the hydraulic cylinder  110  is depicted at  FIG. 2  as a dynamic component of the output of the hydraulic cylinder  110 . The hydraulic cylinder  110  may also include a steady state component (i.e., a static component) that may reflect static loads such as gravity. 
     Turning now to  FIG. 6 , an example method  1000  of controlling vibration in a boom system  10  is given. In particular, the method  1000  may begin at a start point  1002 . Upon starting at the start point  1002 , a decision point  1004  is reached. If the boom  30  is in use, control is advanced to a decision point  1006 . If the boom  30  is not in use, a finish point  1024  is reached. If the boom  30  is moving at the decision point  1006 , control is advanced to step  1008  where the enabler  630  is set to off. Control is then advanced to step  1010  where conventional boom moving control may be implemented. Control then advances to the decision point  1004 . At the decision point  1006 , if the boom  30  is not moving, control advances to step  1012  where the enabler  630  is set to on. Control then advances to decision point  1014 . At the decision point  1014 , if the net load  90  is carried by the chamber  118 , then control is advanced to step  1016  where the chamber  118  of the hydraulic cylinder  110  is locked. Control then advances to step  1018  where vibration control is executed on the chamber  116  and control is then advanced to the decision point  1004 . At the decision point  1014 , if the net load  90  is carried by the chamber  116 , control is advanced to step  1020 . At the step  1020 , the chamber  116  is locked and control then advances to step  1022 . At the step  1022 , vibration control is executed on the chamber  118 . Control is then advanced to the decision point  1004 . 
     Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and spirit of this disclosure, and it should be understood that the scope of this disclosure is not to be unduly limited to the illustrative embodiments set forth herein.