Networked motorized drive roller conveyor

Abstract

A motorized drive roller conveyor includes an upstream zone and a downstream zone, with each zone having a drive roller, an idler roller that is driven by the drive roller, and a sensor. The upstream zone and the downstream zone are controlled by a card, which measures a gap between a first item on the conveyor and a second item on the conveyor by beginning a counter when a trailing edge of the first item passes the sensor of the upstream zone and stopping the counter when a leading edge of the second item passes the sensor of the upstream zone to generate a counter value. If the first item is stopped in the downstream zone, the card of the upstream zone causes the drive roller of the upstream zone to advance the second item into the downstream zone for a distance derived from the counter value before stopping the transportation of the second item.

Description

BACKGROUND AND SUMMARY OF THE INVENTION[0001]The present invention relates generally to a networked motorized drive roller conveyor.[0002]Conventional conveyor control systems utilize a central Programmable Logic Controller (“PLC”) mounted in a central control panel. This type of system requires control devices, e.g., photo-eyes, solenoid valves, and motor starters, to be terminated at the main control panel. A typical control system utilizing a PLC requires several hundred to several thousand feet of control wiring, which requires significant time, labor and money to route and terminate the wiring. In addition, the PLC requires specialized knowledge, e.g., knowledge of ladder logic, and familiarity with the many different interface requirements unique to each manufacturer's product. Moreover, since there is a central controller, response time with respect to the control devices may be increased because the single processor must account for all operations occurring within the system...

AI Technical Summary

Benefits of technology

[0004]For conveyor systems that utilize MDR technology, networked motor controllers are frequently used to handle basic transport, diversion, and accumulation tasks to move items through a conveyor system. These motor controllers are mounted in close proximity to the MDR rollers and directly interface with the product sensors associated with each MDR. An MDR conveyor system has many advantages over other conveyor technologies, such as lower power consumption, noise reduction, and a decreased need for maintenance.

[0005]Unlike conventional control systems, modular distributed controls don't require hundreds to thousands of feet of wiring from a centralized PLC to each device in the system. With controls located near the control devices, wiring and wiring labor may be reduced. This shortens the time to complete implementation and provides a parallel control capability that minimizes response time issues common to conventional PLC based systems. Because the system is not limited by the speed of a central processor in a PLC, the system can grow without worry of overtaxing a centralized controller. Testing and start-up time is also reduced, as various segments of the system can be installed and tested independent of other segments. It is common practice in existing conveyor systems that use MDR roller conveyor along with associated motor controllers to utilize smaller, localized PLC's distributed throughout the system to handle conveyor operations such as diverting, bar code scanning, RFID communication, label applications, etc. These peripherals typically communicate serially (RS232 or RS485) or via a network protocol such as Ethernet. Having multiple PLCs in this environment creates other undesirable issues as single point diagnostics are difficult to implement.

[0006]The networked, distributed control system of the present invention provides localized controls for various operations, e.g., diverting, bar code scanning, RFID transactions, labeling, etc. The inventive control system can also handle the basic MDR conveyor drive and accumulation responsibilities, which greatly reduces the wiring needed for the system, implementation time, and cost while maintaining a centralized diagnostic capability. Additional capability to allow localized programming as well as status and diagnostics capability are additional benefits of the inventive control system. Eliminating the need for PLCs and associated ladder logic is a further benefit of the inventive design because it reduces the complexity of installation, operation and modification of the control system and corresponding conveyor system.

[0007]As noted above, MDR conveyor systems have many advantages over other conveyor technologies, such as lower power consumption, noise reduction, and less maintenance. However, prior to the present invention, MDR systems lacked the ability to control the size of gaps between items on the conveyor system. Prior art systems are also limited to transporting “Items” that are shorter in length than a single “Zone”.

[0009]In accordance with one aspect of the inventive conveyor control system, a gap control arrangement is used to control gaps between items on the conveyor system. The elimination of gaps between items on the conveyor system is desirable, in that gaps reduce the number of items that can be accumulated on the conveyor, providing lower accumulation efficiency. Thus, reducing or even eliminating gaps between items helps to maximize the accumulation efficiency of the conveyor system. The gap control system incorporates the use of MDR technology and its desirable attributes while at the same time providing the operator with the ability to control the size of the gaps between items on the conveyor system.

Problems solved by technology

A typical control system utilizing a PLC requires several hundred to several thousand feet of control wiring, which requires significant time, labor and money to route and terminate the wiring.

Having multiple PLCs in this environment creates other undesirable issues as single point diagnostics are difficult to implement.

However, prior to the present invention, MDR systems lacked the ability to control the size of gaps between items on the conveyor system.

Prior art systems are also limited to transporting “Items” that are shorter in length than a single “Zone”.

The elimination of gaps between items on the conveyor system is desirable, in that gaps reduce the number of items that can be accumulated on the conveyor, providing lower accumulation efficiency.

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