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
 
Matthew Markudis
 
=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=
 
*Complete working concept pictures in build instructions
 
*Complete addition of specific dimensions in build instructions
 
*Complete CAD images in build instructions
 
*Complete addition of CAD files to repository
 
*Complete addition of CAM files to repository
 
*Complete programming instructions in build instructions
 
*Complete shaft encoder circuit diagram and add printed circuit board CAM file to repository
 
*Continue analysis (eg. FEA) and calculations (eg. required torque)
 
*Continue editing bill of materials to parallel development and build instructions
 
=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.
 
=Mass=
 
Given density of A36 steel as 0.28 pounds per cubic inch (numbers are in pounds):
 
*Foundation Underplate: 81
 
*Foundation Pillar: 14
 
*Foundation Overplate: 36
 
*Base Angle: 84
 
*Main Arm: 16.8
 
*Forearm Angle: 42
 
*Forearm Plate A: 5
 
*Wrist Angle: 42
 
*Hydraulic Motor 1: 20
 
*Hydraulic Motor 2: 20
 
*Hydraulic Motor 3: 20
 
*Hydraulic Motor 4: 20
 
*Hydraulic Motor 5: 20
 
*Hydraulic Motor 6: 20
 
*Gearbox 1:
 
*Gearbox 2:
 
*Gearbox 3:
 
*Gearbox 4:
 
*Gearbox 5:
 
*Gearbox 6:
 
=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 wheel 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.
 
=Prototype Development=
 
*As various components of the industrial robot shift from commercial purchase to open source fabrication, design flexibility will increase, improving performance while reducing input resource usage.
 
 
[[Category: Industrial Robot]]

Latest revision as of 11:40, 28 January 2012

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