Note: Descriptions are shown in the official language in which they were submitted.
1156332
AN EQUIPMENT CONTROL SYSTEM WITH FIBER OPTIC
COUPLED REMOTE CONTROL
BRI~F SUMMARY OF THE INVENTION
This invention relates to remote control systems
and particularly to a system in which heavy machinery
controls, such as hydraulic valves, electric drive
motors, or the like, may be accurately controlled via
a fiber optic link that may be several hundred meters
in length.
Remote control systems employing fiber optic links
are particularly valuable for portable operations where
accurate and dependa~le control is required. Unlike
the usual electrical cable or radio control link,
~ibex optics are not affected by external electro-
ma~netic radiation, nor do they radiate a signal that
may ~e dangerous in an explos~ve atmo~phere. In a
fiher optic remote control system there is no danger
to the remote operator from a poisonous environment at
the ~uipment site nor is there a danger that high
2Q volta~e may accidentally be transmitted from the site
t~ the operator. Thus, fi~er optic linked remote
contxol is mo~t v~luable for applications, such as the
cQntrol of machinery in a mine, operation of a crane
~- handl~ng dangerous loads or in a dangerous environment,
~ the maintenance of machinery that may contact high
ltage potentials.
The fi~er optic control system of the present
i~Yent~Qn is descr~Bed in connection with a hydraulic
val~e contxol systemr ~uch as may ~e found on road
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1 156332
construction equipment, cranes or the like. In such
equipment, hydraulic pumps generate high hydraulic
pressures to a fluid which is selectively valved to
appropriate hydraulic actuators, such as hydraulic
cylinders with pistons that may exert many tons of
linear force to lift or move an object. The hydraulic
Yalves for directing the high pressure fluid into the
appropriate actuators are generally manually operated
by an operating lever under the control of the oper-
ating engineer~ In my patent, No. 4,240,304, a valvecontrol system is descri~ed in which the manually
operated valve may be coupled, upon actuation of an
electrical solenoid, to a motor-driven mechanism that
proYides to the hydraulic valve the same actuation
degree and direction that is provided by manual oper-
ation, While the fi~er optic remote control system
described and claimed herein may ~e used to control a
variety of different types of equipment, it is des-
cribed herein in connection with the solenoid coupled
Yalve system of my patent~
Brie,fly described, the present invention includes
a remote control handle unit that may contain various
function switches, potentiometers, and a spring-biased
deadman switch. The Yoltages from various selected
function switches and the levels from the various
potentiometers are converted into digital pulses
haYing Yarious pulse lengths for transmission through
the fi~er optic link to a receiver that reconverts
the digital signals into corresponding analog signals.
The reconYerted binary signals from the function
switches may then ~e used to operate solenoids or
other electrical on-off devices. The voltage levels
deriyed from the remote potentiometers are servoed
against the si~nal levels from e~uipment mounted
position indicating potentiometers to develop error
1 156~32
signals that control the polarity and potential for
driving motors or the like that will reposition the
equipment to the desired location or position.
Many novel safeguards are included. For example,
release of the spring-biased remote deadman switch
grounds all input data and alters the transmission
mode of the fiber optic transmitter. The resulting
received signal represents either the released dead-
man switch, a broken optical fiber link, or a faulty
digital transmission through the fiber and instantly
shuts down the control system for a predetermined
delay period while simultaneously returning all posi-
tioning motors to a neutral predetermined point. A
similar shutdown and delay occurs if an incorrect
function is prematurely selected at the remote handle
to there~y prevent an accidental switching of a
function~ A failure of primary power not only shuts
down the system while activating a standby battery
that repositions the motors, but also releases a
solenoid valve that bypasses high pressure hydraulic
flu~d into the fluid reservoir,
These and other features and advantages of the
system will become apparent from the following draw-
ing&, detailed description and claims.
DESCRIPTION OF TRE DRAWINGS
In the drawings which illustrate a preferred em-
bodiment of the invention:
FIG. 1 is an overall system block diagram of the
fiber optic control used for controlling hydraulic
3Q valves;
FIG. 2 is a schematic diagram of the control
circuitry contained in the remote handle of FIG. l;
FIG~ 3 is a block diagram of the fiber optic
transmitter circuitry;
FIG~ 4 is a ~lock diagram of the fiber optic
recei~er circuitry;
1 1 56332
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FIG. 5 is a simplified sectional elevation view
of one of a plurality of prior art hydraulic valves
to be remotely actuated by the control system; and
FIG. 6 is a block diagram of the hydraulic valve
and motor control circuitry of the invention.
DETAILED DESCRIPTION
If a truck mounted crane or the like is to be used
for handling dangerous loads or is to be operated in
undesira~le or dangerous environments, or if the crane
operator must ~e located away from the manual hydraulic
controls on the crane ~ody in order to accurately oper-
ate the crane, a remote operating position is neces-
sary. As previously discussed, a fiber optic remote
link is most advantageous because it cannot transmit
dangexous electric currents, is impervious to moisture
or dangerous gases, and does not radiate electro-
magnetic signals t~at could, in certain areas, trigger
explosive squibs.
The system of the invention is for a remote control
employ~ng a fi~er optic link ~etween the apparatus
heing controlled and the remote location. The system
is p~rticularly valua~le for remotely controlling the
QperatiOIl Qf a hydraulic valve system on equipment
such as truck cranes or the like and, in the preferred
em~odiment, it ~ill be described for the remote con-
trol of hydraulic valves on a typical truck crane
having a loc~able truc~ cab, storage battery supply,
hydraulic pressure system, and a truck or crane mounted
manually controlled hydraulic valve system that is
described and claimed tn my patent, No. 4,240,304,
Illustrated in the system ~1QC~ diagram of FIG. 1
is a remote control handle lQ having a handle portion
12 and a control section 14~ The control section 14,
~hich is illustrated in the schematic diagram of
~G~ 2~ contains a multiple function selector s~itch
16 ~hich~ ~or reasons to be described later~ is a
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1 156332
single pole multi-position break-before-make switch.
Control section 14 further contains a motor direction
and speed control 18 which, as illustrated in FIG. 2,
is a potentiometer coupled between a 12-volt D.C.
source and ground reference. The center wiper of
potentiometer 18 is spring-biased toward the center
of the potentiometer and therefore, until actuated,
carries a potential of 6 volts.
The control section 14 also contains a spring-
biased normally-open deadman switch 20 positioned in
the control handle 10 so that the thumb or finger of
the operator may conveniently actuate the switch
during remote control operations. As illustrated in
FIG. 2, one terminal of the deadman s~itch 20 is
grounded and the opposite terminal is connected to a
wire in a cable 22 that leads from the remote handle
lQ to the fiber optic transmitter circuitry 24 as
shown in FIG. 1~
Txansmitter circuitry 24 is physically a small
light ~eight package containing not only the trans-
mitter c~rcuitry but also a 12-volt portable battery
pack for powering both the remote handle 10 and the
txansmitter circuitry~ In the preferred embodiment,
the entire transmitter circuitry and battery pack
will be contained in a housing capable of being easily
carried on the operator's belt. The cable 22 would
then have ~ length o~ about three feet or a length
necessary to reach between the belt mounted trans-
m~tter circuitry 24 and the remote handle 10. As will
he d~scussed in detail in connection with FIG~ 3, the
~iber optic transmitter circuitry 24 generates optical
pulse signals c~rresponding to the positions of the
selector switch 16 and the potentiometer 18, but will
onl~ transmit these optical signals if the deadman
s~itch 2~ is closed~
The opti~cal pulse output of the transmitter cir-
cuitry 24 then passes t~rough a fiber optic link 26
1 156332
that may be several hundred yards in length to the
fiber optic receiver circuitry 28 which, to~ether
with a lockable D.C. supply console 30 that is con-
nected to the truck storage batteries, is contained
in the locked truck cab illustrated generally by the
dashed box 32 in FIG. 1. The fiber optic receiver
circuitry 28 converts the optical pulses generated
by the transmitter 24 and r~ceived through the optical
lin~ 26 into analog signals corresponding to the
values set into the control section 14 of the handle
10 and these analog viltage signals are applied to a
hydraulic valve and motor control circuit 34.
The control circuitry 34 operates solenoid couplers
which interconnect the manually operable hydraulic
valve actuators with a motor-driven mechanism that may
be driven forward or reversed to lift or lower the
manual actuators during the periods they are solenoid
coupled~ The movement of the motor-driven mechanism
in the motor and solenoid coupler section 36 is moni-
toxed by a potentiometer similar to the potentiometer16 in the remote handle 10~ Therefore, the hydraulic
~alye and motor control circuitry 34 compares the
positioning of the potentiometer 18 in the handle 10
with the monitored potentiometer associated with the
ralve drive motor and positions the valve drive motor
acc~xdingly~
Many safeguards are associated with the system
and are contained in the hydraulic valve and motor
control circuitry 34. For example, if the truck
stoxage ~attery ceases to function so that all power
is lost, the motor control circuitry 34 releases a
nox~ally-open solenoid valve 38 to permit high
pFessure hydraulic fluid in the system to rapidly
retuxn to the fluid reservoir to thereby cease all
further hydr~ulic operations, An inadvertent release
of the deadman switch 20 in handle 10 will automatic-
ally stop all operations and return the valve drive
1 156332
motor to its neutral position ixrespective of the
positioning of the potentiometer 18 in handle 10.
Provisions are included in the motor control circuit-
ry 34 for similarly stopping all further operation in
the event that the selector switch 16 is switched
before the valve drive motor is returned to its
neutral position and there is an automatic built-in
delay of two or three seconds before the control
system can again be started. Another safeguard is
the including of a standby battery pack within the
hydraulic valve and motor control circuitry. In the
event of a truck power failure, the standby battery
will automatically return the valve drive motor to
a neutral position and will not respond to any fur-
ther remote control until the truck power has beenrestored~
FIG~ 3 i8 a block diagram of the fiber optic
transmitter circuitry 24 of FIG~ 1. The transmitter
circuitry includes a multivibrator 40 hav~ng a period
Of approximately 3~msec. that initiates a chain of
cascaded one~shots 42~50 ~hose pulse lengtAs are
deter~ined by control voltages. Typically~ one-shots
42~5Q may be type 555 timers having their control
v~ltage terminals tpin 5~ coupled to either the wiper
contact of potentiometer 18 of FIG. 1 or to a contact
a~ the ~unction selector switch 16. If the potentio-
metex 18 is used to generate the control voltage to
the one~shot 42~ the output pulse width will vary
between approximately 50~ to 250ausec, according to
3Q the setting o~ the potentiometer 18. Since switches
16 are associated with one-shots 46-48, two discrete
pulse widths will be selectively generated therefrQm.
Qne~shot 5Q is connected directly to ground and
prQ~uces a fixed lengt~ pulse, the purpose of which
will ~e`explained later.
As each of the one-shots 42-50 are progressively
tri~gered ~y the initial action of multivibrator 40,
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the output signals pass through diodes 52-62 to the
trigger input terminal of a one-shot 54 having a
period of approximately lOOusec. As the one-shot 54
is triggered, it forms narrow lOOusec. pulses that
5 vary in position between 500 and 2500usec. to form
fixed frame pulse position modulation of the analog
input signals. The output from one-shot 54 is then
applied to the data input terminal of a commercially
available fiber optics transmitter 56, such as the
10 Model HFBR-1001 fiber optic transmitter manufactured
and marketed by Hewlett-Packard Company of Palo Alto,
California.
The Hewlett-Packard Model HFBR-1001 fiber optic
txansmitter has two operational modes. If an input
15 5ignal to the transmitter mode terminal is at ground
potential, or low, the internal circuitry of the
transmitter generates the necessary optical code to
transmit the input data to the distant receiver where
it is decoded to precisely conform to the transmitter
20 input data. If, on the other hand, the transmitter
mode input is high, internal coding is not provided
and there are no transmitter optical output signals.
Coupled to the mode input terminal of transmitter
56 of FIG~ 3 is one contact of the normally open dead-
25 man switch 20, the other contact of which is grounded.Therefore, when the operator depresses, or closes, the
deadman switch 20, transmitter 56 goes into its low
input mode in which it internally codes the input data
~or transmission to the receiver. The mode input
30 terminal is also connected to the base of transistor
58 which couples the reset terminal one-stroke 54 to
graund, Therefore, ~ith a depressed or closed dead-
man switch 20, transistor 56 is off so that one-stroke
S~ may oper~te and be reset in a normal manner~
~f the operator releases deadman switch 20, the
~ode input terminal of the transmitter 56 is lifted
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1~56332
above ground to its high state in which no trans-
mitter input data is transmitted. The mode input
terminal of the transmitter is connected to the base
of a transmitter 60 coupled between the data input
terminal and ground so that when the mode input goes
to its high state, transistor 60 becomes conductive
to ground all input data. Simultaneously, transistor
58 now becomes conductive to ground the reset terminal
one-stroke 54. The result is that no data enters
transmitter 56 and since the transmitter is in its
high uncoded mode, no optical data will be trans-
mitted therefrom.
FIG. 4 is a block diagram of the fiber optic
receiver circuitry of FIG. 1 and preferably includes
the Hewlett-Packard Model HFBR-2001 fiber optic
receiver 62. This type of receiver has an output
terminal from which dtgital data is produced and a
second or link monitor terminal that provides a
signal indicating link continuity. Thus, a link
monitor output signal indicates that the optical
æignal path has been interrupted by, for example,
broken ca~le~ d~rty connector, or a grounded input
signal such as provided upon release of the deadman
s~itch 2Q,
The pulse position modulation data output from the
recei~er 62 is applied to a sync detecting retrigger-
ahle one-shot pulse detector 66 and to the clock input
term~nals of a D-type flip-flop 68 and a parallel out-
~ut shi$t register 64 which may be a type 74LS164.
~he output of the pulse detector 66 resets the regis-
ter 64 and also the flip~flop 68. Flip-flop 68 has
a grounded D-input to generate, upon reset, a "one"
~utput wh~ch is applied to the register 64 and which
is px~pagated into successive stages of the register
; 35 64 ~r time periods corresponding to the clocked-in
; pulse~pos~tion modulation data or~ginally determined
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~ 15~332
by the one-shots 42-50 in the transmitter circuitry
of FIG. 3. A time gap between the last pulse of one-
shot 54 of FIG. 3 and the next initiating pulse of
multivibrator 40 is detected by the pulse detector
66 of FIG, 4 which then resets the shift register 64
and also resets the "one" generating flip-flop 68.
The output of the pulse detector 66 is coupled to
the input of a sync activity detector 70 which may be
a D-type flip-flop. Activity detector 70 will detect
if two or more sync pulses in series are missing from
the data output train and will apply an output signal
to an OR~gate 72. A second input to OR-gate 72 is
derived from the output signal of the link monitor
terminal of the receiver 62.
The parallel output from shift register 64 is
tri~ered in parallel into buffers 74 and thence into
digital-to-analog circuits corresponding in number to
the capacity of the shift register 64 and/or the
mechanical functions to be controlled. Illustrated
2Q in FIG. 4 are only two output converter circuits
coupled to the output of the buffers 74. The conver-
ter circuit 76 develops an analog output voltage of
6 volts + 5 volts representing the period the binary
"one" remained in the corresponding stage of the
register 64 and hence the position of a potentiometer
such as the motor control potentiometer 18 of FIGS. 1
and 2. The output of the buffer 74 to the circuit 76
includes a resistance-capacitance filter circuit
~pplied to the non-inverting input terminal of an
3a operational amplifier 78 such as the type LM358. ~he
output of amplifier 78 is coupled through a feedback
resistance to its inverting terminal and also through
a resistance to the wiper arm of an offset potentio-
metex 80 coupled between positive potential and ground.
In operation, potentiometer 8~ should be initially
adjusted so that the output voltage of the amplifier
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1 156332
78 is at its mid-value of 6.0 volts, the same mid-
point value of the remote control potentiometer 16
of FIGS. 1 and 2.
Other outputs of the buffer 74 may be applied to
5 other variable voltage circuits such as circuit 76 or
may be applied to analog switching circuits such as
the circuit 82. The buffer output signal is applied
through suitable resistance-capacitance filtering to
the non-inverting input terminal of the amplifier 84,
10 the inverting input terminal of which is coupled to
a reference voltage having a value of about 250mv, or
that which will produce an on or off output control
signal to the base of the output power transistor 86.
~he last output terminal of the buffer 74 pro-
15 vides a signal originating from the fixed period one-
shot 50 of FIG. 3 and is used to provide another input
signal to the deadman O~-gate 7~. This last channel
is decoded by an amplifier 88 and if for any reason
the circuitry fails to detect this last channel, its
signal, together with the link monitor signal, and
the output of the activity detector 70 will produce
an output deadman voltage to the subsequent circuitry.
~ t this point, a brief description of the prior
art valve drive motor and solenoid coupler of FIG. 5
should be presented~ As previously mentioned, the
m~terial included in FIG~ 5 is- fully described and
claimed in my copending patent application Serial
No. g20,674 ~now U.S~ Patent 4,240,304) and is
presented here to illustrate a control mechanism to
~hich the present remote controlling system is parti-
cularly adapted. In FIG. 5, a conventional hydraulic
valve 90 is manually operable by a control handle 92
rotatably mounted to the pivot 94 for operation of
the valve~ A D~C. motor 96 is coupled via a speed
reducing gear box 98 to an output shaft (not illus-
trated) which is attached via a friction clutch to a
cross arm 100. Thus, rotation of motor 96 will tend
1 156332
-12-
to drive the cross arm 100 either up or down depending
upon the polarity of the input power. Arm 100 is
pivoted at 102 to a vertical link 104 which is pivoted
at 106 to horizontal member 108. One end of member
108 is pivoted to a stationary frame at 110 and the
opposite end is coupled to an elongated horizontal
shaft which is moved up or down by rotation of motor
96. Pivoted to shaft 112 is an L-shaped bracket 114
having on the horizontal lip 116 a tubular input shaft
118. A solenoid 120 mounted at the top end of input
shaft 118 actuates an iron core 122 connected to a
shaft 124 th~t is movable within the hollow bore of
the input shaft 118. Coupled to the control handle 92
by an appropriate clevis 126 is a tubular output
shaft 128 having a bore of sufficient diameter to
loosely mate with the exterior walls of the input
shaft 118.
Annular detent rings 130 cut in the interior walls
of the output shaft 128 are aligned to engage spher-
ical balls 132 which lie in apertures 134 in the wallof the input shaft 118 and which are forced through
the apertures 134 into the detents 130 ~y operation
of the solenoid 120 which pulls up the shaft 124 to
force the balls 132 from annular recesses 135 in the
8ha~t 124, Thus, the balls form a connection between
the input shaft 118 and the output shaft 128 whereby
operation of the motor 96 will lift the input shaft
118 and therefore the output shaft 128 and the hydrau-
lic actuator handle 92. Upon release of current in
the solenoid 120, the shaft 124 will drop within the
input shaft 118 so that the balls 132 may again fall
back into the recesses 135 in the shaft 124 to release
t~e input shaft 118 from the detents 130 in the out-
put shaft 128 whereby the output shaft returns to its
naxmal neutral position~
It should be noted that the above represents only
an explanation of tXe simplified construction and
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~ 156332
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operation of the valve drive motor, and only one
solenoid coupler is described~ In practice, one drive
motor 96 is employed to provide vertical movement in
the elongated horizontal shaft 112 and several valve
actuators are coupled thereto, each separately oper-
able by appropriate selection of the remote function
switch 16 of FIGS. 1 and 2. If operation of the
equipment requires simultaneous operation of more
than one function at one time, then additional motor
lQ drive systems such as illustrated in FIG. 5 will be
required and a corresponding number of potentiometers
18 must be added to the remote control handle 10 of
FIGS. 1 and 2.
In FIG. 5, the rotational position of the cross
arm 100 and hence the position of the input shaft 118
is monitored by a potentiometer 140 coupled to the
output ~haft of the gear reducer 98. Potentiometer
140 is coupled between a 12-volt D.C. source and
. ground potential provided by the hydraulic valve and
motor control circuitry 34 and the center arm of
potentiometer 140 accurately transmits a voltage
representing the shaft position or vertical movement
of the input shaft 118 to the circuitry 34.
The hydraulic valve and motor control circuitry
34 o FIG. 1 is illustrated in the schematic diagram
of FIG~ 6. The circuitry of FIG. 6 receives input
signals. from the fi~er optic receiver circuitry 28,
D~C, power rom the truck supply through lockable
switch 30 of PIG. 1, and the input signal from the
3~ center a~m of the shat p~tentiometer 140 of FIG. 5.
: This input from potentiometer 140 is servoed against
the. analog input signal originally derived from the
mqtor direction and speed potentiometer 18 of FIG. 1.
~ The analog sLgnal representing motor direction and
;~ 35 p~sition.and derived from the remote control is
receiv.ed from the receiver circu~try at input terminal
~: 142 of FIG~ 6 and is txansmitted through normally
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~ ~56332
closed relay contacts 144 to the non-inverting input
terminal of a comparator 146. The D.C. signal derived
from the center arm of the potentiometer 140 of FIG. 5
is received at input terminal 148 and is transmitted
to the inverting terminal of the comparator 146. The
output of the comparator is applied to the inverting
terminal of operational amplifier 149 and to the non-
inverting terminal of a similar amplifier 150. The
opposite input terminals of amplifiers 149 and 150
are suitably biased by a voltage divider coupled
between 12 volts and ground potential. Also coupled
between 12 volts and ground potential are NPN switch-
ing transistors 152 and 154 in series and transistors
156 and 158 in series. The output terminal of ampli-
fier 149 is coupled to the ~ase of transistor 152 andto the base of transistor 158. The output terminal
of amplifier 150 is coupled to the base of transis-
tors 154 and 156. One output conductor to the motor
terminals 160 is coupled to the interconnection of
the emitter of transistor 152 and collector of tran-
sistor 154. The second motor conductor is connected
to the interconnection of the emitter of transistor
156 and collector of transistor 158.
~f the input signals to the comparator 146 are
identical, the output signals from amplifiers 149 and
15Q will ~e zero and all transistors 152-158 will be
off to produce a zero potential across the motor
terminals 160. Whenever there is a difference at the
input terminals of the comparator 146, there will be
a corresponding d~fference in outputs of amplifiers
149 and 150, one ~eing positive and the other negative.
;~ If ~mplifier 149: generates a positive output, tran-
sistors 152 and 158 will conduct and a 12-volt poten-
t~al ~ill pass through transistor 158 to the corres-
ponding motor terminal 160~ Similarly~ since tran-
SistO 158 is also conducting, its collector is at
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1~56332
-15-
ground potential and the corresponding potential is
applied to the opposite motor terminal 160. It can
be seen, therefore, that the analog voltage inputs
at input terminals 142 an~ 148 will control the
polarity and voltage to the motor 96 of FIG. 5.
Relay 162 which includes contacts 144, operates
to provide circuit safety features as previously
discussed, If, for example, a signal is received at
the deadman input terminal 164, it will pass through
the OR-gate 166 to the excitation coil of the relay
162, and thence through normally closed con~acts of
the relay 168 to ground potential. The resulting
current through the coil of relay 162 will open the
contacts 144 to prevent the analog signal appearing
at input terminal 142 from reaching the comparator
146~ The opening of the contacts of the relay 162
also applies a current through the contacts 180 to
the relay excitation coil to lock the relay 162 in
its excited position. A conductor 170 coupled to the
mid-point of a resistance voltage divider between the
12~vQlt and ground potentials, and therefore at a
level of 6 volts, is coupled to the alternate, or
excited terminal of contacts 144 and also to the
excited terminal of the contact 180. Thus, whenever
the coil of relay 162 is energized, a 6-volt signal
is applied to the non-inverting terminal of the
comparator 146 to there~y produce a required voltage
at the motor terminals 160 that will return the motor
~6 to its neutral position, at which point the monitor
3Q potentiometer 140 of FIG. 5 will be centered to
produce a corresponding 6-volt output signal.
Motor terminals 160 are connected to both the
inverting and non-inverting input terminals of ampli-
fieræ 172 and 174, the output terminals of which are
coupled to the input of a NOR gate 176. Amplifiers
172 and 174 and the NOR-gate 176 comprise a zero motor
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1 15:6332
-16-
voltage detector circuit so that, with no potential
across motor terminals 160~ the output signals from
amplifiers 172 and 174 will be zero and the output
of NOR-gate 176 will be high. The output of the NOR-
S gate 176 is applied as one input to the AND-gate 178,
the second input o~ which is obtained from the contact
180 of the relay 162. Thus, when relay 162 is activa-
ted, the terminal 180 is connected to the conductor
17Q carrying six volts. Therefore, AND-gate 178,
receiving both the high output from NOR-gate 176 and
the 6-volt output through contacts 180, produces an
output signal through an RC delay network wh~ch will,
after a predetermined time of two to three seconds,
open the contacts of the relay 168 to break the cur-
lS rent flow through the coil of relay 162 and permitthe contacts to return to their normal position. It
will be noted, therefore, that any output potential
across the motor terminals 160 will cause the NOR-gate
176 to produce a low output and a corresponding low
output of the AND-gate 178, hence relay 162 will remain
activated for a period of two to three seconds after
the motor terminals 160 have finally acquired an equal
patential,
D~C. power input to the circuitry of FIG 6 is
received from the truck mounted power console 30 on
the 12-volt power conductor 182. Coupled between
conductor 182 and ground potential is a relay coil
184 which actuates relay contacts 186 and 188. Norm-
ally open contacts 186 are connected between conductor
182 and through an isolation diode 187 to the circuit
~cc conductor so that when the coil 184 is excited by
an input potential on conductor 182, a 12-volt poten-
tial is applied to the circuitry of FIG. 6. In the
event of a power failure, coil 184 is released and
the relay contacts 188 now connect the standby power
pack lgQ through an isolation diode 192 to the cir-
cuitr~ of FIG~ 6~ When power is lost on conductor 182
332
and standby power is applied to the circuitry, the
standby voltage is also applied as one input to the
OR-gate 166 to thereby open the relay 162 in a manner
similar to a deadman input signal at input terminal
164. The standby power from battery 190 through diode
192 into the circuitry provides sufficient power to
operate the hydraulic valve and motor control circuitry
34 and to provide adequate power to return the motor
96 of FIG. 5 to its neutral position. The isolation
diodes 187 and 192, however, prevent standby power
from returning to the fiber optic receiver circuitry
or from other power consuming equipment associated with
the truck crane,
Conductor 182 is also connected to a solenoid of
a hydraulic valve 194 preferably connected between the
hydraulic pump output, or primary pressure lines and
the low pressure hydraulic reservoir. Loss of input
power on conductor 182 will release all high pressure
h~draulic fluid from the system ~y releasing the
excitation current from a normally-open solenoid
operated valve 194 which, while closed ~y the activa-
ted ~olenoid, prevents the high pressure fluid from
returning to the hydraulic fluid reservoir.
Solenoid switching signals received from the fiber
optic receiver circuitry of FIG. 4 pass directly
through the control circuitry to the corresponding
solenoid couplexs, described in FIG. 5. Each of the
solenoid signal lines passing from the receiver to
the solenoids of FIG~ 5 is tapped in the control
circuitxy of FIG. 6 and the tap is applied to the
input terminals of a NOR-gate 200, the output of
which is appl~ed to the input of an AND-gate 202.
The second input terminal to AND-gate 202 is received,
invexted, from the output of the NOR-gate 176 which
produces a high output only when there is no motor
po~ential at term~nals 160.
11~6332
-18-
As previously mentioned in connection with FIG. 2,
the multi-function selector switch 16 is a break-before-
make switch so that any rotation of the selector switch
will produce a break or a zero output. This break is
sensed by the NOR-gate 200 of FIG. 6 and produces a
high output to the input of AND-gate 202. If there
is a potential across the motor terminals 16Q, NOR-
gate 176 produces a low output which, after inversion,
becomes a high input to AND-gate 202. Thus, a motor
potential across terminals 160, together with the high
output from NOR-gate 200, causes AND-gate 202 to
produce a high output to activate relay 162. However,
if the motor is neutralized and no potential appears
across motor terminals 160, NOR-gate 176 produces a
low input to AND-gate 202 to produce a low output into
the OR-gate 166. It follows~ therefore, that no changes
may be made in the multi~function selector switch 16
before the motor 96 of FIG. 5 has returned to its
neutral position and it is therefore impossible to
acciden'ally change a function that may cause a crane
or simila~ apparatus to attempt conflicting functions~
The fiber optic remote control system of the
inYention will therefore accurately position hydrau-
' lic actuators, one at a time~ in accordance with the
command of the remote operator. It will be appreci-
ated that any number of motors may be controlled by
the circuitry of the invention and that the binary
si~nals which have been described in connection with
sQlenoid actuators may be used for other purposes,
3a such as the control of remote switches or alarms, or
; the like.
Having thus described my invention, what is claimed
lS ;
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