Portable precision synchronized lifting

Abstract

A portable modular synchronized hydraulic system coordinates the motion of multiple hydraulic actuators using a processor-based controller that determines valves actuation times based on pump, pistons, and valve characteristics and user settings for load movement. The controller receives position sensors data and accounts for pump, pistons, and valve characteristics. System components can be battery-powered and can be manually transported in groups of interconnected equipment cages.

Description

[0001] PORTABLE PRECISION SYNCHRONIZED LIFTING

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003]

[0001] This application claims priority to U.S. Non-Provisional Application No. 63 / 568,209, filed March 21, 2024, the disclosure of which is hereby incorporated by reference in its entirety.

[0004] TECHNICAL FIELD

[0005]

[0002] This disclosure relates to synchronized hydraulic operations such as lifting buildings and industrial equipment.

[0006] BACKGROUND

[0007]

[0003] Conventional synchronous hydraulic lifting systems use PLC (Programmable Logic Controller) devices to monitor and coordinate high-pressure hydraulic pistons for lifting houses and other heavy objects.

[0008] SUMMARY

[0009]

[0004] A processor-based controller for synchronized hydraulic operations determines valve actuating times to coordinate precise motion of a set of hydraulic actuators to ensure accurate coordinated movement of a load. The controller monitors various aspects of one or more hydraulic circuits such as overall system pressure, flows to specific actuators, movement, and positions. The controller receives receive position data sensors associated with hydraulic actuators such as pistons, and simultaneously and independently controls each actuator via a separate valve for each actuator.

[0010]

[0005] Valve actuation can be controlled by varying firing rates, e.g., down to 50 mS or lower, and up to 1000 mS or higher. The valve actuation period is determined based on adjustable parameters for each hydraulic actuator, its associated valve, the hydraulic capacity and pressure source for the circuit, and a desired rate of change of position of the actuator. Such control can achieve actuator movement precision for each actuator and / or between actuators within 1 mm.

[0011]

[0006] The system can be modular and portable, e g., such that components such as the controller, actuators, sensors, hydraulic pressure source, and associated hydraulic lines, wiring, etc., can be moved by hand singly or in sets, either by themselves or mounted in stacking transportation cages.

[0007] The controller processor can be a microprocessor or microcontroller, for example. Similarly, the controller can make use of field-programmable gate arrays (FPGAs) and / or custom integrated circuits (ICs).

[0012]

[0008] System components can run on common or shared electrical power, which can be line power, battery power, battery backup power, or a combinations thereof. System components can communicate via wired and / or wireless links. For example some links can be analog or digital point-to-point wired links, fiberoptic, and / or ethemet connections. Wireless connections such as Wi-Fi, Bluetooth, Zigbee, cellular, or other standards can be used for aspects of the system.

[0013]

[0009] Controllers can be interconnected for coordinated operation of multiple banks of equipment and / or for redundancy for safe operations. Controller, actuator, valve, and / or sensor data can be monitored and / or analyzed locally and / or remotely.

[0014]

[0010] A manual and mechanically assisted transportation of system components can be achieved using interlocking cage modules arranged in configurable vertical stacks. For strength and visibility through the stack, each cage can be a rectilinear frame with symmetrical fittings at a top surface and a bottom surface of the cage, such that the fittings at the top of a first cage abut the fittings at the bottom of a second cage atop first cage. Cages can be fixed to each other by pins, bolts, locks, etc. Equipment, drawers, supplies, etc., can be mounted inside cages, and carry handles can be attached to sides. Shield to protect equipment can be placed on one or more side, top, or bottom of a cage. A cage or stack of cages can be fitted with wheels, e.g., casters or a trolley, for manual ground transport. Similarly, a cage or stack of cages can be fitted with a lifting strap, e g., for assembly or disassembly of a stack, and / or loading or unloading at a transport vehicle.

[0015] BRIEF DESCRIPTION OF THE FIGURES

[0016] [Oil] Figure 1 illustrates a cage for used in a modular equipment transportation system.

[0017]

[0012] Figure 2 illustrates a stack including two cages.

[0018]

[0013] Figure 3 illustrates a cage with installed casters.

[0019]

[0014] Figure 4 illustrates a stack of cages with an integrated trolley.

[0020]

[0015] Figure 5 illustrates a stack of cages with a lifting strap.

[0021]

[0016] Figure 6 illustrates a stack of three cages on casters.

[0017] Figure 7 is a schematic of single hydraulic circuit powering four cylinders that are controlled individually by associated wireless valves and monitored by wireless position sensors using a central electronic controller.

[0022]

[0018] Figure 8 illustrates a system that includes twelve cylinders operating on two hydraulic circuits wherein the cylinders are controlled by three electronic controllers.

[0023] DETAILED DESCRIPTION

[0024] INTRODUCTION

[0025]

[0019] Traditionally, synchronized hydraulic lift systems use Programmable Logic Controllers (PLCs) and integrated hydraulic pumps. These PLC-based systems are generally reliable, but often cumbersome and inflexible. Changing to microprocessor technology offers many advantages, but systems must be further adapted to exploit these advantages. Herein, a number of solutions are described which can be used in any combination, including adaptations of electronic controller units, hydraulic components, sensors, actuators, electronic hardware, and software.

[0026] Battery Power

[0027]

[0020] For example, with the lower power requirements of high-reliability electronic components such as microprocessors, microcontrollers, custom integrated circuits, programmable gate arrays, and field programmable gate arrays, it is possible build a battery-powered central controller for synchronized hydraulic lift operations. Further, by selecting lower voltage and lower power devices generally, the whole system can be battery-powered, e.g., operating from a central power pack, or with batteries distributed on various items of equipment.

[0028] Wireless Sensors and Actuators

[0029]

[0021] The extra processing capacity of microprocessors and similar electronics allows the integration of wireless communications between the controller and critical sensors and / or actuators, reducing the need for field cabling while allowing measures for security, integrity, and safety of these data connections.

[0030] Decoupling Hydraulic Source and Control

[0031]

[0022] The lower power requirements of microprocessor and similar electronics is to allow smaller and lighter systems. Traditionally, synchronized hydraulic lift systems incorporate a hydraulic pump. This simplifies design of the PLC control system, since the parameters of the pump can be taken as constant. However, the adaptability of microprocessor-based controller can be exploited to adapt the system to work with any pump. This modular approach opens a wide range of opportunities for applications of the operations, such as using pumps that already located at a work site, or bringing in a pump sized appropriately for the job, rather than a standard large integrated pump designed to handle a wide range of applications.

[0032] Portability

[0033]

[0023] The move from PLC to processor technology, and the modularization of synchronized hydraulic equipment, permit new approaches to the ease of transport of equipment. This includes use of modular equipment transport cages which can be interconnect with each other and with handling and transit fittings and shields for improving portability.

[0034] MECHANICAL TRANSPORT

[0035]

[0024] Smaller, lighter, modular systems present different challenges and opportunities versus traditional systems which, if portable, can be truck or skid mounted. One approach to exploit the reductions in the size and weight of system components is to provide a modular transport system.

[0036] Single Cage

[0037]

[0025] Figure 1 illustrates a cage in which equipment can be mounted. The cage is a three- dimensional rectangular frame with cage-to-cage mounting brackets located on the top and bottom of the cage. Cage 100 of Figure 1 features vertical members 102 and horizontal members 104 which join to form sides of the cage 100, and lateral members 110 which connect the sides. Cage 100 also features optional lifting handles 120 and shields 130. In practice, equipment can be attached to various members in the space between the sides and between the top and bottom lateral members 110.

[0038]

[0026] Shields 130 can be affixed to any side of a cage, and / or to the top or bottom. Further, in practice, the shields can be limited in size, or even omitted, e.g., to permit the maximum visibility around the equipment and / or access to the equipment when the equipped cage is in position at a job site.

[0039]

[0027] In the example of Figure 1, the cage has side grip bar handles 120 for manipulating the cage. In practice, grip bars or other handles can be placed on either side, the front, and / or the back of any cage.

[0040] Stack of Cages

[0041]

[0028] Figure 2 illustrates a scenario 200 with an operator 240 and a stack of two cages, an upper cage 210 and a lower cage 220. The cages in the example of Figure 2 are similar to cage 100 of Figure 1, featuring side handles and shields. The upper cage 210 is of a different size than the lower cage 220. The cages however have compatible upper and lower surfaces which permit them to be stacked one on the other in any order. For example, the upper and lower surfaces can feature bosses and recesses, not shown, for alignment and connection of the cages. The example of Figure 1 shows the cages being locked together with pins 230. The pins 230 can be spring-loaded and / or captive pins, for example, and / incorporate boss and or recesses / chambers for facilitating alignment of the cages prior to locking them into position. Similarly, the cages can be affixed using bolts, locking hasps, and the like.

[0042]

[0029] The cages can be of any size. Operator 230 is included to illustrate an example scale for the cages, wherein a single operation can be able to reach both handles of a cage. Similarly, two operators can bear the weight of a cage or a stack of cages by grasping handles on either side.

[0043]

[0030] In the example of Figure 2, upper cage 210 is loaded with drawers 212 for transport of, e.g., tools, wires, connectors, sensors, and the like. Lower cage 220 is loaded with hydraulic control equipment 222. In practice, the equipment 222 can be any hydraulic equipment such as pumps, valves, hoses, and tools, power sources and / or converters, and electronic controls, sensors, cables, and / or communications gear. As will be appreciated, the cages can be used for the transport of other types of work site equipment, tools, and supplies.

[0044] Caster Option

[0045]

[0031] Figure 3 shows a single cage 300 with casters 350 affixed to its lower surface. Like cage 100 of Figure 1, cage 300 is made of vertical, horizontal, and lateral members 302, 304, and 310, respectively. In this example, the casters 350 are each affixed separately, bolted to lower horizontal members 310 with pins 352. The bolt locations can double, for example, as recesses for aligning cages. Alternatively, separate caster assembly can be affixed to the bottom of a cage, e.g., using the same alignment and locking mechanisms used to connect cages in a vertical stack. Trolley Option

[0046]

[0032] Figure 4 illustrates a stack 400 of two cages 404 and 406 mounted on a trolley 402. The upper cage 404 is affixed to lower cage 406, e.g., via locking mechanisms not shown. Similarly, the stack 400 is further affixed to trolley 402, rather than merely resting on trolley 402. As with the caster assembly described in connection with Figure 3, here in Figure 4 the trolley 402 can be connected to the lower cage 406 using fittings on cage 406 that can be used for attaching another cage. Alternatively or additionally, the trolley 402 can be affixed to the upper cage 404 and / or the lower cage 406 along the vertical members of the cages.

[0047] Lifting Strap Option

[0048]

[0033] Figure 5 shows a stack 500 of cages 504, 506, and 508 where the cages are affixed to each other. A lifting strap 502 is attached to the upper cage 504, such that the stack 500 can be lifted as a unit using strap 502. The strap 502 can be affixed to the upper cage 504 using fittings that are also used to affix other cages. Additionally or alternatively, a strap can be affixed by other means to the vertical, horizontal, or lateral members of an upper cage, for example. The strap permits a cage or a stack of cages to be moved into or out of the bed of a truck at a worksite, for example, without requiring disassembly of the stack.

[0049] Tall Stack

[0050]

[0034] Figure 6 illustrates a stack 600 of three cages on casters. Cages can be arranged in any order to any height or width. For best manual handling, stacks can be limited, as illustrated in Figure 6, to a size manageable by a single operator, with a height and wheel size appropriate for ground conditions at particular worksites.

[0051] CONTROLLER

[0052] Example Hydraulic Circuit

[0053]

[0035] Figure 7 illustrates a system 700 with a hydraulic circuit that is operated wirelessly by a processor-based electronic controller 740. The hydraulic circuit includes a hydraulic pressure source 702, e.g., a pump, powering four pistons 710. Hydraulic fluid to the pistons 710 is gated by associated valves 730. The position of each piston 710 is monitored by associated position sensors 720, which can be string position sensors, e.g., using potentiometers. The controller 740 controls the valves 730 via wireless links 744 and receives position sensor 720 data via wireless links 742.

[0054]

[0036] The controller 740 can receive other inputs and / or communications via links 746 and provide other outputs via links 748. In practice any of links 742, 744, 746, and / or 748 can wired or wireless, and unidirectional or bidirectional.

[0055]

[0037] The system 700 can include other sensors, devices, and controls not shown, such as additional hydraulic devices, e.g., safety devices, redundant position sensors, hydraulic and / or power condition sensors, etc.

[0038] The controller 740 can be microprocessor, microcontroller, FPGA, and / or custom IC based to provide flexible operation, communications with other devices, and the like. For example, the controller 740 can provide secure control linkages to phone, tablet, and / or computer-based user interfaces. Alternatively or additionally, the controller can provide a variety of safety and / or power monitoring capabilities, e.g., for power-battery operations of parts of the system 700 or the entire system 700.

[0056] Adaptability

[0057]

[0039] To accommodate a variety of hydraulic variables, such as pump, valve, and cylinder flow rate / capacity and rates of motion and travel, the controller 740 of Figure 7 can be configured to allow manual entries by a user as to a variety of parameters, and / or provide a number of selectable presets for one or more of the pump, valves, and cylinders used. Similarly, the controller can be arranged to provide manual adjust and / or presets specific to a job and / or class of jobs for which the controller a hydraulic setup is used.

[0058]

[0040] For example, the controller can adjust valve operating parameters, such as valve firing rate, to adjust for different pump sizes and / or different maximum desired rates of motion of achieved during lifting. Similarly, electrically controlled return velocity damping can be used to control retraction speed and ensure controlled movement in return mode.

[0059] Precision

[0060]

[0041] Precision in cylinder motion for lifting and / or retraction can be achieved in a number of ways. The controller can measure actual movement, e.g., through the use position sensors 720 such as linear wire encoders to track movement. The rate of movement can be controlled in very small increments, e.g., through control of valve firing rates. For example, solid state relays can be used to achieve valve firing rates down to 50 mS cycles or lower.

[0061] MULTIPLE CONTROLLERS

[0062]

[0042] Figure 8 illustrates a system 800 using multiple controllers 820, 840, and 860 controlling three banks 822, 842, and 862 of hydraulic equipment. Each bank 822, 842, and 862 includes four pistons. As in the example of Figure 7, here in Figure 8 each piston has an associated valve and an associated position sensor. In theory, any controller can control any of the pistons, and further can control any number of pistons. In practice, e.g., for wired valve controls and / or wired sensor data, the number of pistons controlled by a single controller can be limited to, e.g., four or more pistons. The exact number controlled can depend on a number of factors, such as: valve firing rates; sensor data precision; use of redundant sensors; communications mechanisms, rates, security, and / or redundancy; and / or safety mechanisms.

[0063] [0431 In the example of Figure 8, two type hydraulic circuits are used. Hydraulic source 810 powers a hydraulic circuit that includes banks 822 and 842. Hydraulic source 870 powers bank 862. The controllers 820, 840, and 860 can be adjusted to compensate for the use of different sizes and / or capabilities of the sources 810 and 870, and / or for differences among pistons, valves, and sensors.

[0064]

[0044] Synchronization of hydraulic operations can be achieved by a number of means such as initial configuration, sensing, trigger communications, coordinated remote control, and / or communication between the controllers. In the example of Figure 8, the controllers 820, 840, and 860 communicate via a network made up of a wired link 880 between control 820 and controller 840 and a wired link 882 between controller 840 and controller 860. Links 880 and 882 can be, e.g., RS485 standard digital communication current loop links.

[0065] CONTROLLER OPTIONS

[0066] Communications Links

[0067]

[0045] In practice, communication links between controllers and between controllers and sensors, pistons, pumps, etc., can be point-to-point, bussed, or multipoint wired links, and / or wireless or fiberoptic links, for example. For certain operations, such as hydraulic operations, as opposed to data downloads, initial configuration, and / or software maintenance, high reliability links such as RS485 communications can be preferred, e.g., to avoid dangers of radio interference. Network Self-configuration and Self-termination

[0068]

[0046] In the example of Figure 8, the links 880 and 882 are point-to-point connections. This allows, for example, self-configuration and / or self-termination of wired communications links. For example, each controller can be fitted with a wired communication input and a wired communication output. In the example of Figure 8, controller 820 knows that it is the first controller in a chain of controllers because its wired communications input port is unconnected, but its output port is connected. Similarly, controller 840 knows that it is the middle of a communication chain, and controller 860 is the last controller in a chain of connected controllers. The controllers can thereby configure themselves for communications. Additionally or alternatively, bussed and / or wireless networks of controllers can be used. Failure Detection and Recovery

[0069]

[0047] The use of processor-based controllers allows several modes of failure detection and recovery. For example, safety shutoffs can be triggered with measured conditions exceed preset limits. The can include automatically shutting down a hydraulic power source, opening and / or closing valves, and / or sounding, sending, and / or displaying alarms.

[0070]

[0048] Redundant pumps, sensors, and / or pistons can be included in circuit setups, whereby the controller can detect and compensate for malfunctions without loss of control, allowing operations to be safely completed or, at a minimum, brought safely to a halt.

[0071]

[0049] The controller can compare piston motion relative to an estimate of motion based on valve actuation for a given load. Failure to move can mean, for example, that: the load is underestimated; motion of the load is unexpected blocked; there is a piston or hydraulic line leak, etc. Disparate displacement along a beam can mean, for example, that the beam has cracked and / or bowing more than expected.

[0072] Adjunct Computing Equipment

[0073]

[0050] In addition to user setup and control interfaces, sophisticated modeling, monitoring, and safety technology can reside in the controller and / or in other computer equipment that is in communication with the controller. For example, local wired or wireless interfaces can connect smart phones, tablets, laptops, and / or other devices to the controllers, whereby complex applications and interfaces can be used on such devices to monitor and / or control operations.

[0074]

[0051] Similarly, data recording, extraction, and analysis can be achieved for hydraulic, mechanical, electronic, and / or power performance measurements within the controller and / or by sending data via memory cards, wired data pathways such ethernet and / or USB, and / or wireless pathways such as Bluetooth, WIFI, Zigbee, and / or cellular pathways, for instance.

[0075] Secure Independent Operation of Controllers

[0076]

[0052] Controllers can be configured for secure communications and / or for independent operation in the absence or loss of communications with devices including, but not limited to, local devices such as other controllers. That is, controllers can be firewalled against unauthorized access or control, for example, and configured for safe operations in the event of power and / or communications loss and / or interference. Hence processor-based controllers, for example, can be connected to and / or use more networks and more kinds of networks than are used by PLC-based systems, and yet at the same time have lower requirements for network communications and / or data exchanges to achieve safe execution of complex hydraulic operations.

[0077] Power Sources, Power Isolation, and Battery Safety

[0078]

[0053] Referring again to Figures 7 and 8, various system components can be powered by different means. For example, hydraulic sources can be combustion or electric powered, while controllers, valves, and sensors, are powered by AC line power and / or conditioned DC power sources such as battery bank or separate batteries. Each individual system component can be corded, wireless, or both. Power monitoring and / or switching, as well as electronical isolation of communication links, can be employed to ensure safe operation and / or permit switchover to backup power and / or communications links.

[0079]

[0054] To address challenges arising from reliance on battery power for modular synchronized hydraulic equipment, controllers and / or other and equipment can be fitted with battery sensing and switching equipment. For example, in the case that battery discharge threatens to cause damage to one or more batteries and / or an interruption of an operation underway, relays can be used to disconnect threatened batteries and / or switch in backup batteries. This can be accomplished quickly, for example, through the use of solid-state relays.

[0080] GENERAL USES

[0081]

[0055] The synchronized hydraulic control techniques described herein can be used in a wide variety of applications where, for example, high precision of applied force and / or movement of multiple hydraulic actuators is useful. This includes, but is not limited to, for example: positioning equipment, e.g., in industrial and / or agricultural maintenance, repair, and or operations; building construction, maintenance, repair, and operations; materials loading and transport; aligning and / or skidding heavy loads; inflation and / or deflation pressurized vessels, etc.

[0082]

[0056] The techniques described herein permit precision control of a masses in motion, e.g., through the measurement of movements and metering of the energies involved. The modularity of the systems using these techniques permits great portability and ease of deployment, e.g., of corded and cordless equipment, allowing access wherever loads are found. For example, whether the load is a whether it is abridge, a building, industrial equipment, lifting, lowering, tilting, and / or positioning can be achieved in situ automatically with a high degree of accuracy. Microprocessor- controlled digital actuation and digital control provide significant advantages including time savings, repeatability, and extremely low internal stress in the object being moved. Motion can be measured increments of less than one millimeter. Piston action can be tightly controlled via extremely short actuation durations, e.g., of 50 mS or less, separately for each valve at separate times, such that only small units of oil are directed to the selected hydraulic cylinders at any given moment. With this "partitioning" of the hydraulic oil, the hydraulic system becomes a virtual digital hydraulic system with all advantages of checkability and control over the movement of the load. Subsequently, with all movement points being synchronized and under full control, stresses are induced into the object being moved due to bending, torsion or shifting loads can be minimized or eliminated.

[0083]

[0057] The use of processor-based controllers can minimize or eliminate the use of manual interventions by operators, and thereby improve accuracy and save time versus conventional techniques. Similarly, digital operations can be better observed, recorded, and documented.

Claims

CLAIMSWhat is claimed is:

1. A first controller for hydraulic operations, the first controller comprising a computer processor, a user interface, and non-volatile memory comprising processor instructions, wherein the first controller is configured via the instructions to: receive position data from each position sensor of a first set of position sensors, the first set of position sensors being associated with a first set of hydraulic actuators in a first hydraulic circuit; and simultaneously and independently control each hydraulic actuator of the first set of hydraulic actuators by actuating a separate valve for each hydraulic actuators of the first set of hydraulic actuators, wherein: each separate valve is assigned an actuation period between 50 mS and 1000 mS; and the actuation period is determined based on adjustable parameters for each of the associated hydraulic actuator, the associated valve, a hydraulic pressure source for the first hydraulic, and a rate of change of position detected by an associated position sensor.

2. The first controller of claim 1, wherein the computer processor is a microprocessor or a microcontroller.

3. The first controller of claim 1 or claim 2, wherein the first controller is battery powered.

4. The first controller of any of claims 1-3, wherein the first controller actuates the separate values via one or more first wireless links.

5. The first controller of any of claims 1-4, wherein: the hydraulic actuators are pistons; and the first controller controls the position of each piston within an accuracy of 1mm.

6. The first controller of claim 5, wherein the first controller controls the position of each piston within an accuracy of 1 mm from piston to piston.

7. The first controller of claim any of claims 1-6, wherein the first controller receives data from each position sensor via one or more second wireless links.

8. The first controller of any of claims 1-7, wherein the first controller is connected via a network connection to a second controller, the second controller managing a second plurality of hydraulic actuators, wherein each hydraulic actuator of the second plurality of hydraulic actuators has an associated valve operated by the second controller and a position sensor monitored by the second controller.

9. The first controller of claim 8, wherein the first controller is configured to: detect a failure of the second controller; and, in case of failure of the second controller, operate the second plurality of hydraulic actuators.

10. The first controller of claim 8 or 9, wherein the network connection to the second controller is a third wireless link.

11. A transportation system for a modular synchronized hydraulic system, the transportation system comprising a set of cages arranged in a vertical stack, wherein each cage is a rectilinear cage comprising: vertical, horizontal, and lateral members forming a rectilinear frame; symmetrical fittings at a top surface and a bottom surface of the cage, such that the symmetrical fittings at the top of a first cage abut the symmetrical fittings at the bottom of a second cage, the second cage atop and abutting the first cage, such that the first and second cage can be securely affixed to each other, and such that each cage can be in any vertical position in a stack of cages; and a hydraulic equipment controller mounted in one of the cages of the set of cages.

12. The transportation system of claim 11, further comprising a set of casters affixed to a bottommost cage of the set of cages.

13. The transportation system of claim 12, where in the set of casters is affixed to one or more of the symmetrical fittings at the bottom surface of the bottommost cage.

14. The transportation system of claim 11, further comprising a trolley affixed to a bottommost cage of the set of cages, the trolley comprising a pair of wheels and a pair of steering handles.

15. The transportation system of claim 14, wherein the trolley is affixed to one or more of the symmetrical fittings at the bottom surface of the bottommost cage.

16. The transportation system of any of claims 11-15, further comprising a lifting strap affixed to the top surface of a topmost cage of the set of cages, the lifting strap comprising a lifting point connected to a plurality of flexible connectors for connection to the top surface.

17. The transportation system of claim 16, wherein the flexible connects are attached to symmetrical fittings of the top surface of the topmost cage.

18. The transportation system of any of claims 11-17, wherein an individual cage of the set of cages has one or more lifting handles for separate handling of the individual cage.

19. The transportation system of claim 18, wherein the individual cage has a vertical shield occluding a portion of a vertical side of the individual cage.

20. The transportation system of claim 18, wherein the individual cage has a vertical shield occluding a portion of a vertical side of the individual cage.

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