APPLICATION FOR LETTERS PATENT

A Redundant Motor System in a High-Payload

Electro-Mechanical Rotary Joint

Inventors:

Eric Eller

Forrest Monroe Brock Blackburn

ATTORNEY'S DOCKET NO. SAT.0103PTWO

BACKGROUND

Motor failures are typically dealt with by removing the failed equipment from service to diagnose the problem. Once a motor failure is determined the motor is replaced or repaired. Upon completion of repairs the equipment is then placed back into service.

SUMMARY

A redundant motor system is described. In one exemplary aspect, the redundant motor system includes a planetary gearbox that is coupled to a primary motor and a secondary motor. The primary motor drives the planetary gearbox, while at the same time back-driving the secondary motor via the secondary motor coupling also located at the planetary gearhead. The secondary motor includes a resolver operatively coupled to send first signals indicating primary motor status information to a control system. The resolver is also configured to send second signals to the controls system once the secondary motor has been activated. Responsive to failure of the primary motor and receipt of corresponding commands from the control system, the secondary motor is placed into service to drive the planetary gearbox.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the following Detailed Description section. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the Figures, the left-most digit of a component reference number identifies the particular Figure in which the component first appears.

Fig. 1 shows an illustration of an exemplary redundant motor system operatively coupled to a high payload electro-mechanical rotary joint, according to one embodiment.

Hart IP Law and Strategies, LLC 1 Atty Docket No. SAT.0103PTWO (303) 534-1015 Fig. 2 shows an illustration of an exemplary secondary/redundant motor of a redundant motor system, according to one embodiment.

Fig. 3 shows an exemplary exploded view illustration of a high payload collector-mechanical rotary joint that utilizes an exemplary redundant motor system, according to one embodiment.

DETAILED DESCRIPTION

Fig. 1 shows an illustration of an exemplary redundant motor system 100 operatively coupled to a high payload electro-mechanical rotary joint 101, according to one embodiment. The redundant motor system 100 provides a novel redundant motor design (a redundant motive source for the drive train) for systems (e.g., the electro-mechanical rotary joint 101) that allows it to be driven given a motor failure. This design allows a high ratio gearbox to be driven with either a primary or a secondary/redundant motor. In one exemplary implementation, the joint 101 is a shoulder joint. As shown in Fig. 1, system 100 includes a primary motor 102 and a secondary motor 104. In this particular implementation, two motors 102 and 104 are mounted in parallel to each other. Primary motor 102 has a cogged pulley 106 attached directly to the drive shaft of the primary motor 102. Secondary motor 104 has a shaft adaptor (Fig. 2) that carries a resolver rotor component (a portion of which is shown as 108 - resolver stator). An end opposite the motor drive shaft of secondary motor 104 carries cogged pulley 110. The resolver stator 108 and resolver stator housing 112 is assembled to the output side of the secondary motor 104. The rotor and stator combination generates motor position and speed information for communication to a control system 114. In one implementation, control system 114 is operatively coupled to but remote from redundant motor system 100. In one exemplary implementation, for example, the redundant motor system 100 is part of joint 101, which is utilized to inspect and repair material/components in a highly radioactive or other hazardous environment. In such a scenario, the control system 114 is

Hart IP Law and Strategies, LLC 2 Atty Docket No. SAT.0103PTWO (303) 534-1015 operatively coupled (e.g., wired or wireless coupling) to and remote from the redundant motor system 100 to protect operational characteristics of the control system 114 from hazards associated with the particular environment within which redundant motor system 100 and the joint 101 operates. As illustrated in Fig. 1, control system 114 comprises a processor 116 operatively coupled to a system memory 118. System memory comprises program modules 120 comprising computer-program instructions and program data 122. The computer program instructions of program modules 120 are configured to monitor signals received from joint 102 and send commands responsive to interpreting such received signals. More specifically, the computer-program instructions, when executed by the processor 116, monitor primary and secondary motor (102 and 104) statuses (e.g., operational or failed). In one implementation, the computer program instructions also monitor other characteristics of the redundant motor system 100 such as speed information and/or so on. In the event that primary motor failure is detected, the computer program instructions switch primary motive operations of the joint 100 to the secondary motor 104. Exemplary structure of the redundant motor system 100 providing for motor redundancy, for example, to electromechanical joint 101 are now described in greater detail. Referring to Fig. 1, planetary gearbox 124 carries two cogged pulleys 126 and 128. Pulley 126 is dedicated to interface with the primary motor pulley 106, wherein as planetary gearbox pulley 128 is dedicated for secondary motor pulley 110. In both instances of this example, the interface is achieved using a cogged belt, although other interfaces can be used without departing from the scope of the described system. In this implementation, belts are used because of the variety of sizes; no need for lubricant and very low stretch characteristics. In this exemplary implementation, primary 102 and secondary 104 motor assemblies are built to allow for adjustable locations. This is to allow for belt tensioning.

Hart IP Law and Strategies, LLC 3 Atty Docket No. SAT.0103PTWO (303) 534-1015 Under normal operation, primary motor 102 drives the system 100 through planetary gearbox 124. The planetary gearbox input shaft has pulleys 126 and 128 directly connected to respective ones of motors 102 and 104. So while the primary motor 102 drives planetary gearbox 124 in normal operations (absent a primary motor failure), the planetary gearbox of this configuration back-drives secondary motor 104. This motion allows resolver components (Fig. 2), which in this exemplary implementation is attached to the secondary motor 104, to deliver motor speed and position data to the control system 114 for the primary motor 102. In conventional systems, motor signals/measurements are generally provided directly from the motor that is being measured (e.g., the primary motor). Here, however, secondary motor 104 of system 100 provides motor information to control system 114 for both motors (e.g., under normal operation or otherwise by inference). This exemplary implementation allows for a reduced number of resolvers to provide motor information to a control system, reduces weight of the redundant motor system, and thereby the overall weight of joint 101 as compared to conventional joints, and further providing for a reduced total size of the system 100 and joint 101 package as compared to conventional joints.

Under off-normal conditions, where primary motor 102 fails (e.g., burns out) or otherwise stops working (e.g., due to belt failure), secondary motor 104 is activated responsive to receipt of a command by the control system 114. In this particular implementation, motors 102 and 104 are designed to fail in a free spin state in the event of a motor burn out. Such a free spin failure mode allows secondary motor 104 to drive planetary gearbox 124 and back-drive a failed motor (e.g., primary motor 102). Accordingly, strategic placement of a resolver in a redundant motor 104 allows for motor data to be generated and provided to control system 114 regardless of which motor (e.g., 102 or 104) is driving the planetary gearbox 124. In the event of a belt failure associated with primary motor 102, secondary motor 104 would drive planetary gearbox 124 while primary motor 102 is disconnected from the drive train.

Hart IP Law and Strategies, LLC 4 Atty Docket No. SAT.0103PTWO (303) 534-1015 In one implementation, the control system automatically instantiates a redundant motor such as secondary motor 104 to drive the planetary gearbox 124 in place of the primary motor 102 or a different redundant motor (e.g., one of multiple secondary/redundant motors 104). Fig. 2 shows exemplary aspects of a secondary/redundant motor 104 comprising resolver components to measure characteristics of a primary motor, according to one embodiment. As illustrated in figure 2, secondary motor 104 is operatively coupled to resolver housing 202 and cogged pulley 110. Resolver housing 202 comprises a shaft adapter 204, resolver rotor 206, and resolver stator 108.

Fig. 3 shows an exemplary exploded view illustration of a high payload collector- mechanical rotary joint 101 comprising the exemplary redundant motor system 100, according to one embodiment. In Fig. 3, the left-most digit of a component reference number identifies the particular Figure in which the component first appears.

Alternate Embodiments

In another embodiment, the redundant motor system 100 of Fig. 1 comprises more than a single secondary/redundant motor. In this alternate embodiment, there are a series of redundant motors, wherein one (or more) of the redundant motors comprises a resolver 108 for communication with control system 114 to provide information pertaining to more than a single motor to control system 114. In one implementation, for example, redundant motor system 100 comprises first and second (or more) redundant motors operatively coupled to a primary motor and a planetary gearbox. In this example, and under normal operations where the primary motor is driving the planetary gearbox, the first and second redundant motors are back-driven, and the second redundant motor comprises a resolver in communication with the control system. In the event that the primary motor fails, the second redundant motor in communication with the control system causes the control system to

Hart IP Law and Strategies, LLC 5 Atty Docket No. SAT.0103PTWO (303) 534-1015 instantiate the first redundant motor to drive the planetary gearbox. In this scenario, the primary motor is back-driven (or disengaged from the joint 101 drive train) and the secondary redundant motor is back-driven. In this example, and in the event that the first redundant motor fails, the second redundant motor in communication with the control system is activated to drive the planetary gearbox and back-drive the first redundant motor.

Although this alternate embodiment describes first and second redundant motors, a chain of n redundant motors can be implemented, for example, in view of a priority criteria to indicate which particular redundant motor drives the planetary gearbox in the event of another mo tor (s) failure. Although this example indicates that a single redundant motor of multiple such redundant motors comprises a resolver operatively coupled to the control system, in another embodiment, multiple such redundant motors comprise respective resolvers in communication with the control system as described herein.

Conclusion

Although an exemplary high payload electro-mechanical rotary joint has been described in language specific to structural features and/or methodological operations or actions, it is understood that the implementations defined in the appended claims are not necessarily limited to the specific features or actions described. Rather, the specific features and operations of the exemplary high payload electro-mechanical rotary joint are disclosed as exemplary forms of implementing the claimed subject matter.

Hart IP Law and Strategies, LLC 6 Atty Docket No. SAT.0103PTWO (303) 534-1015