Industrial Robot Development: Difference between revisions

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{{ToolTemplate|ToolName=Industrial Robot}}
#REDIRECT [[Industrial Robot/Research Development]]
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=Master Diagram=
 
[[Image:IRMaster.jpg|500px]]
 
=Developers=
 
Paul Azevedo
 
Yoonseo Kang
 
Wonjohn Choi
 
Joshua Lee
 
Roberto Bortolussi
 
=Progress Report=
 
General Developmental Bill of Materials Completed
 
Mechanical Design Illustrated
 
Denavit-Hartenberg Kinematic Parameters Completed for Sample Design
 
Electrical Design Illustrated
 
Hydraulic Design Illustrated
 
Stepper Motor - Needle Valve Bracket Design Illustrated
 
Systems Engineering Diagrams Added
 
=Task List=
 
Continue design optimization and understanding through research and collaboration
 
Complete analysis (deflection)
 
Complete calculations (required torque)
 
Complete all CAD files
 
Complete all CAM files
 
Complete detailed bill of materials
 
Complete build instructions
 
Complete user's manual
 
=Design Rationale=
 
*Using hydraulic drive over electric drive: electric drive requires complicated electronic circuits, requires a high reduction gearbox (such as harmonic drive, which is complicated to design and fabricate), and is not as scalable as hydraulic drive (for very high loads).
 
*Needle valves and solenoid valves over proportional servovalves: proportional servovalves experience coil heat buildup that changes the resistance of the solenoid hence diminishes its accuracy of control; proportional servovalves also are more complicated to design and fabricate.
 
*Stepper motors to allow the electronic control of needle valves: eliminates need to have closed-loop system for needle valve control while maintaining high accuracy through stepping.
 
*Two plate, four pillar design for foundation: simple to design, fabricate, and assemble, does not require casting with molds while maintaining high degree of stability.
 
*Angles and bars frame design: simple to design, fabricate, and assemble, does not require casting with molds while maintaining high degree of stability akin to the designs of existing commercial industrial robots.
 
*Spur gearbox: High efficiency, minimal axial force transmitted onto shaft; simple to design, fabricate, and assemble relative to other gearbox types (such as planetary or harmonic).
 
*Incremental Encoder: simpler design, higher resolution, more economical relative to absolute encoders. Achieves absolute positioning capability through homing.
 
=Repeatability=
 
The precision of the industrial robot is determined by the following factors (assuming sufficient control over hydraulic motors where the minimum non-zero movement interval causes a degree of movement that is less than the arc length of one encoder sector):
 
*Deflection of frame components
*Resolution of shaft encoders
 
Repeatability then can be improved by the following methods:
 
*By bolstering the structural rigidity of the industrial robot, minimizing the deflection factor
*By augmenting the resolution of the shaft encoder, minimizing the resolution factor
 
Methods of improving the factors affecting repeatability include various considerations:
 
*Greater frame component volumes are more rigid but more heavy as to cause more and less deflection in certain regions (deflection-deflection tradeoff)
*In a gear reducer, the closer the stage to which the encoder wheel is connected, the lower the effective resolution (deflection-resolution tradeoff)
*In a gear reducer, larger encoder wheels necessitate larger and potentially less rigid container walls (resolution-deflection tradeoff
*In a gear reducer, perpetual contact between gears must be maintained for accuracy of the microcontroller's observation for the relationship between the mechanical state and the encoder's electronic output
 
=Frame and Gear Reducer Integration=
 
*Through design that integrates each gear reducer with corresponding frame components, material requirements are decreased while ease of fabrication, maximum payload, and structural rigidity all potentially increase.
*This integration does not allow gear reducers and frame pieces to be modules independently of each other; the extent to which the robot's components are modular is increased by one system level (instead of separate frame pieces and gearboxes, integrated frame-gearbox components)
*The extent of modularity does not change, however, for the following 2 critical frame components, still allowing the robotic arm to be versatile with regard to usage (different lengths and working envelopes are possible):
**Main arm
**Forearm
*Also, the end-effector remains modular as frame-gearbox integration does not affect such external components.
 
 
[[Category: Industrial Robot]]

Latest revision as of 11:40, 28 January 2012

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