Industrial Robot Proposal
Industrial Robot Prototype
by Yoonseo Kang
September 21, 2011
msn149@hotmail.com
Abstract: – The industrial robot partial prototype consists of the fabrication, assembly, and testing of 1 axis for future integration into a fully operational 6-axis robotic arm that is teachable by jogging in either cartesian or joint space, and controllable with g-code. The industrial robot serves as a universal “user” machine that can be utilized for the automation of a wide variety of processes including welding, pick-and-placing, torching, and more; given the industrial robot's high reach, payload, speed, and duty cycle, robotic automation allows a significantly high rate of production with relatively minimal operator involvement. More broadly, automation lies at the core of productivity and economic freedom. With regard to distributive enterprise, robotic processes can be shared among communities through digital files, the use of which are more simple and less time-consuming than applying equivalent manual processes. For the GVCS, the industrial robot is the means with which a small group of individuals can achieve enormous productive potential; for civilization, the arm-like universal automation machine at the core of flexible fabrication infrastructure. Economic analysis suggests that the industrial robot's output is at least twice the rate of manual performance for most desired tasks, mainly attributable to the machine's high duty cycle. The expected deployment timeline for the industrial robot partial prototype is under 1 month given complete access to the required resources; for the full prototype integration, similar timing as sourcing and infrastructure permit.
Deliverables – General time allocation for the partial prototype as follows: 4 weeks for sourcing. 1 day for soldering and assembling electronics as well as connecting the hydraulic circuit. 2 days for fabrication and assembly of structural components. 3 weeks for software file development and testing. Ensuring the functionality of 1 axis control, hydraulics, and structure is optimal preparation for manufacturing the remaining 5 axes.
General time allocation for the full prototype as follows: 4 weeks for sourcing. 5 days for soldering and assembling electronics as well as connecting the hydraulic circuit. 20 days for fabrication and assembly of structural components. 5 days for 6-axis testing.
The partial prototype contains a fraction of the components in the following diagrams:
Mounting Diagram for Hydraulic Motor and Encoder onto Structural System
Diagrams – Above
Industry Analysis – Current costs of some commercially available industrial robots are shown here. In comparison, attributable to the hydraulic drive, open-source control system, and simplified structure, the cost for the OSE industrial robot is approximated to be significantly lower (as will be specified in the cost analysis) while performance expected to match commercial standards. Significant modularity allows interchangeability of components (for instance, the encoder) for even higher resolution; open source fabrication of major components such as the hydraulic motor and slewing bearings will drastically reduce total cost in the near future.
Scaling calculations – To scale up reach, the structural system need only be enlarged. To scale up torque, the slewing bearing size can be increased, multiple motors can be geared to a single slewing bearing, and/or a planetary gearbox can be attached to the face of the hydraulic motor. To increase encoder resolution, an encoder with greater cycles per revolution can be utilized. To increase operating bandwidth, faster electronics can be incorporated overall into the control system (such as using the 5i20 card instead of 7i43, and/or using daughter cards for step/dir generation). The aforementioned modularity allows easy changes to overall characteristics.
Systems Engineering Breakdown Diagram –
OSE Specifications Assessment –
Open-sourced:
*PWM Driver
*Stepper Driver
*Control Software
*Supporting Frame
Not yet open-sourced:
*Hydraulic Motor
*Hydraulic Filter
*Pressure Relief Valve
*Stepper Motor
*Needle Valve
*2/4 Solenoid Valve
*Slewing Bearing
*Incremental Encoder
*Electric Power Supply
*Anything IO Card
*Computer
Design:
The software side of the control system (emc2) is already open-source and built for customization and modification (even with help programs for custom HAL and INI files in specialized applications). Furthermore, the operator may choose to use a wholly different software for the control system, for which the compatibility is mainly attributable to the versatile “Anything I/O Card”.
The hardware side of the control system is a simple network of 5 major components including the computer, anything IO card, stepper driver, pwm driver, and power supply. Any component can be switched for another of the same function easily with terminal block connections.
The hydraulic system is also a relatively simple circuit that is easy to modify and assemble.
The structural system includes simple components such as 1-piece foundations and frame connections. The absence of a dedicated gearbox significantly lowers the complexity of this system (the gear reduction between the motor shaft pinion and geared slewing bearing provides sufficient torque due to hydraulic drive). Even a directly coupled shaft-to-frame connection is available as an option, as is the use of a planetary gearbox or multiple motors on one bearing as mentioned in the scaling analysis.
Resources – The major resources required for manufacturing the industrial robot partial and full prototype include various GVCS tools: Precision CNC Multimachine, Drill press, Torch Table. Additionally, hand tools include wrench set, hex key set, tap and die set.
Timeline – 1 month plan for partial prototype: 3 days for completion of tangible manufacturing given access to required resources as aforementioned in “Deliverables”. 3 weeks (rest of the month) for finalizing software files, testing, and uploading documentation.
1 month plan for full prototype: 25 days for completion of tangible manufacturing given access to required resourced as aforementioned in “Deliverables”. 5 days for finalizing 6-axis testing and uploading documentation.
Project Plan – For partial prototype:
Electronics: Solder PWM Driver 1.1, then connect electronics as shown in the electronics diagram but for 1 axis
Hydraulics: Connect components as shown in the hydraulic diagram but for 1 axis. Fabricate and assemble the stepper mount, then fit it onto the needle valve.
Structure: Drill holes in foundation and shoulder angle, assemble by sandwiching (bolts/nuts) the slewing bearing between those two components. Fabricate the pinion gear, mount the hydraulic motor, fabricate the encoder coupling, mount the encoder, fabricate and assemble cover components.
Budget – See Industrial Robot Bill of Materials
Assessment – Functionality, proximity to expected characteristics, and potential for future improvement. These 3 assessment criteria will aid in understanding the differences between the design and actual prototyping process, as well as setting the ground for better development in the future.
Failure Mode Analysis and Recovery Plan –
Industrial robot function substitutes and enhancements are discussed here as options.
*Flow Control: Use higher torque step motors or proportional valves
*Structural Angle: Use short reinforcing angles or thicker metal
*Slewing Bearing: Use external gear slewing bearing with zero backlash worm or higher-precision slewing bearing with internal gear
*Anything IO: Use Mesa 5i20
*Mechanical Stiffness at Axes of Rotation: Use back-end flow control orientation, autocorrecting movement software configuration, or
*Intergear Spacing: Use higher precision gears or spring-loaded double gear design