Control system for a materials-handling device, especially for a shelf storage and retrieval device

A control system for a materials-handling device, especially for a shelf storage and retrieval device. The device includes a horizontal travelling mechanism having a horizontal drive; a lift truck which can be raised and lowered on a mast via a lifting drive; and a storage/retrieval drive for storage and/or retrieval of the goods to be handled. The present system provides a simplified assembly and a design with respect to the supply of current. The simplified assembly and design is accompanied by supplying the electrical power for the storage/retrieval drive and for data transmission with a signal converter through the use of contact conductors arranged on the mast and the power is picked up from the contact conductors by sliding contacts on the lift truck.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a control system for a materials-handling 
device, especially for a shelf storage and retrieval device, including a 
horizontal travelling mechanism having a horizontal drive (x); a lift 
truck, which can be raised and lowered on a mast via a lifting drive (y); 
and a storage/retrieval drive (z) for storage or retrieval of the material 
to be handled. 
2. Description of the Prior Art 
Rail-mounted materials-handling devices for the transport, storage and 
retrieval of unit loads, e.g., pallets in shelf warehouses, are well 
known. The transport and warehousing operations of the storage and 
retrieval device are carried out along a passageway, the longitudinal 
sides of which each form a shelf. The storage and retrieval device is 
equipped with a travelling drive in the x-direction and a lifting drive in 
the y-direction for transporting the unit load along the shelf. The 
storage and retrieval of the unit load on and from the shelf is carried 
out by a driven telescopic or drawing device which works in the 
z-direction and is positioned on the lifting device moved by the lifting 
drive. 
The travelling drive moves the device on the travelling rail along the 
length of the shelf. The lift truck is run on a mast of shelf height, and 
is raised or lowered using a support device, e.g., cable or chain. 
A control job for the automatic sequence of transport and storage 
operations includes essentially position control for the travelling and 
lifting devices and position and process control during the storage and 
retrieval process carried out by the load holding device on the lifting 
device. 
The drives and associated sensors for the movement sequences are 
concentrated locally on the travelling unit and the lifting device. The 
necessary electrical signal connections and the motor feed line are run 
via the mast, which is otherwise needed only for mechanical support and 
guidance functions. According to the prior art, these electrical 
connections are established by cable lines between the travelling unit and 
the lifting device. Trailing cable connections of this type can have up to 
140 leads and require high installation expenditure. In addition, such a 
structure entails great expense for cabling to the height-adjustable 
lifting device. In cable connections between the lifting device and the 
mast, on the one hand, and between the mast and the travelling unit, on 
the other, the establishment of control can be terminated only in 
connection with the mast. Given the size of the storage and retrieval 
device, it is important, for reasons related to manufacturing technology 
and transportation between the manufacturing site and the usage site, to 
be able to manufacture the lifting device, mast and travelling unit 
separately and to establish the electric connections at the interfaces of 
these modules upon assembly. In addition, expenditures for cable lines as 
used in prior art devices and for their required assembly as well as for 
the maintenance necessitated by ongoing bending stress are extremely high. 
SUMMARY OF THE INVENTION 
The present invention is based primarily on providing an economic control 
system designed to provide automatic shelf storage and retrieval of 
devices wherein the lifting device, the mast and the travelling unit can 
be manufactured and transported separately. This eliminates the problems 
associated with establishing the electrical connections, as the components 
are assembled and the electrical connections are established by simply 
fitting the components together through respective connectors. This 
invention also reduces the number of electrical conductors or leads 
required. 
According to the present invention, the electrical power for both the 
storage/retrieval drive and the transmission of data by a signal converter 
can be supplied by contact conductors arranged on the mast. This power can 
be picked up from the contact conductors arranged on the mast through 
sliding contacts on the lift truck. The electrical connections between the 
height-adjustable lifting device and the mast are established via the 
contact conductors. Using this design, it is therefore possible for the 
lifting device, the mast and the travelling unit to be manufactured and 
transported separately and for the electrical connections to be 
established simply by fitting together the aforementioned components, 
whereby, in addition, the number of electrical conductors to the lift 
truck can be significantly reduced. Furthermore, signal currents and motor 
currents can be run relatively close to one another without impermissible 
interference. 
According to the present invention, spring-activated carbon strips are 
arranged as sliding contacts on one guidance frame of the lift truck. By 
means of the exact guidance of the lifting device, the spring-activated 
carbon strips provide an interruption-free electrical connection between 
the carbon strip and the contact conductor along the lifting mast. The 
electrical connection between the lifting device and the mast is 
established in the course of mounting the lifting device on the mast, 
without special expenditure related to the contact conductors. 
Advantageously, the electrical connection between the mast and the 
horizontal travelling unit can be established at low cost by means of a 
connector, arranged on the mast, at the lower end of the contact 
conductors. 
Furthermore, it is also advantageous that the conductive contact-conductor 
path of a contact conductor at the upper end of the mast and of the same 
contact conductor or another contact conductor at the lower end of the 
mast is shortened, so that the conductive segment limits the movement area 
for raising and/or lowering the lifting device by interrupting a control 
current circuit. If this area is overtravelled at the ends, a current 
circuit which had been closed via a connection between a carbon strip and 
a contact conductor is interrupted in a path-dependent fashion, fulfilling 
the safety requirement for a movement limiting control, in connection with 
the contact conductor on the mast, in a simple manner. 
The present invention is designed such that the signals of the lifting 
device are conducted by a signal converter in the vicinity of the carbon 
strips in such a way that the signal converter includes the conductor 
connections for the signals, is equipped with signal displays, and 
converts the parallel signals into a serial data transmission telegram. In 
this way, the number of necessary contact conductors in the wide range is 
independent of the number of signals to be transmitted. 
As the present invention has a reduced number of loop conductors, it is 
advantageous to surround the contact conductors carrying the motor 
currents by protective conductors, so that a screening effect can be 
maintained with respect to closely adjacent contact conductors for control 
currents and data transmission signals. 
A further feature of the present invention is that the distance between 
contact conductors, which are rectangular in cross-section, is as small as 
possible, and the distance from the contact conductors to the conductive 
mast, with interconnection of an insulating profile, is also as small as 
possible. In order to achieve the screening effect, the contact conductors 
have a flat rectangular cross-section, and a constant narrow distance of 
approximately 2.5 mm between adjacent conductors in the insulating support 
profile. In addition, the distance to the wall of the mast is small 
(approximately 12 mm), and the mast is produced from electrically 
conductive material, e.g. steel, which, when magnetized, additionally 
screens the magnetic field of the motor currents. 
Another feature of the present invention is that the contact conductors 
consist of parallel adjacent contact conductors for motor currents, 
control currents and data transmission signals. 
As noted above, the shelf storage and retrieval devices are equipped with 
three main movement axes, namely, the horizontal drive (x), the lifting 
drive (y) and the storage/retrieval drive (z). Each drive includes a 
motor, a drive regulator, a speed control and a position control. The 
movement sequence for the transport and storage function of the shelf 
storage and retrieval device is carried out by a superordinated control of 
the drives. However, the electrical line connection between the lifting 
device and the travelling mechanism with the hook-up to the superordinated 
control can be established only when, according to further features of the 
invention, the signals of the lift truck are fed into a signal converter 
in the vicinity of the sliding contacts and can be transmitted by the 
signal converter, via the sliding contacts, to a position and process 
control as a serial data transmission telegram. 
A further feature of the present invention is that the horizontal drive (x) 
and the storage/retrieval drive (z) are both connected to the same power 
regulator and the same speed control, and perform position and process 
control using a shared superordinated control. 
Another feature of the present invention is that a change-over switch is 
associated with the drive regulators for the horizontal drive (x) and the 
storage/retrieval drive (z), which, when controlled through the 
superordinated control, switches between the horizontal drive (x) and the 
storage/retrieval drive (z). 
A particular advantage of the control system according to the present 
invention is attained via contact conductors to the lift truck through a 
parameter change-over between travel and storage/retrieval. Here it is 
advantageous that the drive regulator or the speed control for the 
horizontal drive (x) and the storage/retrieval drive (z) are operable 
based on a set of control parameters. The control parameters are either 
transmitted during a change-over by the superordinated control or are 
stored in the drive regulator and speed control and can be activated by a 
change-over command from the superordinated control. 
This type of drive control mechanism, with a shared drive regulator and 
speed control for the movement along the x and z axes, saves the expense 
of having a separate drive regulator and speed control for the 
z-direction. In addition, because movement along the z-axis is only 
permitted when the x-axis is turned off, in terms of drive, no loss of 
handling power is experienced in the shelf storage and retrieval device. 
The mass to be moved by the storage/retrieval drive (z) is always smaller 
than the mass moved by the horizontal drive (x), and thus, the power of 
the drive regulator for the horizontal drive (x) is always sufficient to 
move the mass of the storage/retrieval drive (z) in this arrangement. It 
is therefore advantageous that the connection between the superordinated 
control and the speed control or the power regulator for one of the 
horizontal drive, the storage/retrieval drive and the lift drive is 
designed as a serial data bus, via which the parameter sets, as well as 
the target speed values and the control data can be transmitted. 
Furthermore, it is advantageous that each drive, which includes a motor, a 
power regulator, a speed control and a position control, can be 
coordinated through a superordinated control during the movement sequence 
of the transport and storage function of the device. 
An example of the invention is shown in the attached drawings and described 
below in greater detail. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of the disclosure. For a better understanding of the invention, its 
operating advantages, and specific objects attained by its use, reference 
should be had to the drawing and descriptive matter in which there are 
illustrated and described preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A control system included on a materials-handling device 100, especially 
for a shelf storage and retrieval device is shown in FIG. 1. This device 
100 includes a horizontal travelling mechanism 102 having a horizontal 
drive 104, a lift truck 106 which can be raised and lowered via a lifting 
drive 108, shown in FIG. 3, on a mast 110, and a storage/retrieval drive 
112 for the goods (not shown) to be handled. 
The electrical power for the storage/retrieval drive 112 and for a signal 
converter 114 is supplied by contact conductors 116 arranged on the mast 
110. The contact conductors 116 can be more clearly seen in FIGS. 4 and 5 
and will be further discussed hereinafter. The supplied power can be 
picked up from the contact conductors 116 by sliding contacts 118 on the 
lift truck 106. The sliding contacts 118 may be comprised of spring 
activated carbon strips connected to a guidance frame 120 of the lift 
truck 106. The carbon strips or sliding contacts 118 are coupled between 
the contact conductors 116 and both the storage/retrieval drive 112 and 
the signal converter 114 for supplying power between the contact 
conductors 116 and both the storage retrieval drive 112 and the signal 
converter 114. The lift drive 108 is also supplied with power from the 
contact conductors 116 through the sliding contacts 118. Power is supplied 
to any or all of the devices connected to the sliding contacts based upon 
the connections established between the sliding contacts 118 and the 
contact conductors 116. As the sliding contacts 118 are connected to the 
storage/retrieval drive 112, the signal converter 114, and the lift drive 
108, power is supplied to the particular device or devices for which the 
sliding contacts 118 establish a connection with the contact conductors 
116. The contact conductors 116 comprise parallel adjacent contact 
conductors 122 for motor currents and contact conductors 124 for control 
currents and data transmission signals as is shown in FIG. 5. The 
electrical connection between the mast 110 and the horizontal travelling 
mechanism 102 is established through a connector 126 at a base of the mast 
110, as can be seen in FIG. 1. The connector is arranged at the lower end 
128 of the contact conductors 116 shown in FIG. 4. As is also shown in 
FIG. 4, the contact conductor path 130 includes contact conductors of 
differing length, as will be explained in more detail below. 
The signals of the lift truck 104 are transmitted by the signal converter 
114 positioned in the vicinity of the sliding contacts 118, to a position 
and process control 132 shown in FIG. 3. The position and process control 
132 includes a process control 134 and a position control 136 for the 
respective axes, x, y, and z. The horizontal drive 104 and the 
storage/retrieval drive 112 are both attached to the same power regulator 
138 and the same speed control 140. The position and process control 132 
is carried out by a shared superordinated control 142 within the position 
and process control 132. 
A drive regulator 144, including both the power regulator 138 and speed 
control 140 for both the horizontal drive 104 and the storage/retrieval 
drive 112, is associated with a change-over switch 146, which is 
controlled through control signals received along the line 166 from the 
superordinated control 142. The change-over switch 140 selects between the 
horizontal drive 104 and the storage/retrieval drive 112 depending on 
control signals generated by the position and process control 132. 
The power regulator 138 and the speed control 140 for both the horizontal 
drive 104 and the storage/retrieval drive 112 are operable based on a set 
of control parameters, which may be transmitted during a change-over by 
the superordinated control 142 or may even be stored in the power 
regulator 138 or the speed control 140, and are activated by a change-over 
command from the superordinated control 142. A connection 148 between the 
superordinated control 142 and the speed control 138 or the power 
regulator 140 for the horizontal drive 104 and the storage/retrieval drive 
112, and the speed control 150 or power regulator 152 for the lifting 
drive 108 exists along a serial data bus 154. The parameter sets, the 
speed target values and the control data can all be transmitted via this 
data bus 154. 
Each drive, as shown in FIG. 2, includes a motor 156, 158; or 160, a power 
regulator 138; 152, a speed control 140, 150 and a position control 136 
and can be coordinated through the superordinated control 142 during the 
movement sequence of the transport and storage function of the device. 
As shown in FIG. 4, the conductive contact-conductor path 130 of a contact 
conductor 116 may be shortened at the upper end 162 of the mast 110, and 
the same contact conductor or a different contact conductor 116 may be 
shortened at the lower end 164 of the mast 110, so that the conductive 
section limits the movement area for raising and lowering by interrupting 
the control current circuit. 
The signal converter 114, which includes line connections for the signals, 
is equipped with signal displays and converts the parallel signals into a 
serial transmission telegram. The signal converter 114 is located on the 
lift truck 104, as is shown in FIG. 1. 
The contact conductors 122 which supply the motor power are surrounded by 
protective conductors, so that a screening effect can be maintained with 
respect to the closely adjacent contact conductors 124 for control 
currents and data transmission signals. Such can be seen in FIG. 5 and 
will be further discussed below. 
As is shown in FIG. 5, previous contact conductor arrangements for shelf 
storage and retrieval devices, which include approximately 140 leads, are 
reduced to a total of only 18 contact conductors under the principle of 
the contact conductors used in the present invention. The especially 
interference-critical data bus contact conductors (identified by reference 
numbers 15 to 18 in FIG. 5), on which, for example, only currents of 
approximately 50 milliamperes flow at .+-.24 V, are spatially separated 
from the lines which conduct the motor power, in order to keep 
interference effects low (problem of electromagnetic compatibility). 
The inventive arrangement of the contact conductors, for example, in the 
arrangement in FIG. 5 with the contact conductor of only 18-poles, was 
selected in such a way that the lines conducting the motor power 
(designated by reference numbers 2 to 4 in FIG. 5), which usually transmit 
several kW, are surrounded by the aforementioned protective conductors 
(designated by reference numbers 1 and 5 in FIG. 5). The protective 
conductors provide a screening effect to the closely adjacent signal and 
data lines. 
The intermediate space between the power contact conductors and the data 
transmission contact conductors is utilized to supply power for the other 
current consumers of the lift truck 104, e.g., for final controls, 
electric brakes and separately controlling drives. 
The invention is not limited by the embodiments described above which are 
presented as examples only but can be modified in various ways within the 
scope of protection defined by the appended patent claims.