001 - First Calibration of SCARA Manipulator

Group members:
Allan Hendry -- Mechanical Design / Machining
Adam MacLean -- Control System Design / Electrical Design / Programming
Krista Trahey -- Mathematical Modeling / Documentation

Background:
We are a group of Mechanical Engineering students at Lakehead University in Thunder Bay, Ontario, Canada.

Our final degree project is the design, construction, and control of a SCARA2 robotic manipulator.

The project was entirely student funded and constructed.

The manipulator does not use the traditional SCARA1 joint layout with the prismatic joint located above the end effector. Instead, due to constraints imposed by the difficulty involved in the design and construction of the traditional layout, the prismatic joint is at the base of the arm. This layout is the less popular SCARAII layout.

The design of the manipulator was completed in Solidworks 2007 and machined entirely by Allan.

The motors are all brushed servos running at 12V off of a generic 400W PC power supply. The two revolute axis are belt driven (2:1) off of harmonic drive gear boxes (50:1) yielding a drive ratio of 100:1.

The control system is running a simple position loop on a dsPIC33 microprocessor programmed in MikroC on a Mikroelektronika LV24-33 development board. PD control will be implemented in a later revision of the control software.

The motor are connected to 1000 or 2000 pulse per revolution optical encoders. The A/B outputs form the encoders are fed into quadrature decoder chips (LSI LS7184) that convert the signal to Pulse/Direction signals so that each axis requires a single hardware interrupt instead of two and no decoding software is needed for the quadrature signals.

Category:

Education

Tags:

• SCARA
• SCARAII
• SCARA2
• Robot
• Robotics
• Control
• Mikroelektronika
• dsPIC
• dsPIC33
• Harmonic
• Drive
• Solidworks
• Lakehead
• University

[SCARAControl001]

The dsPIC has a single quadrature decoder, since we have 3 axis we needed three decoders.

[uno1dos]

how do you control the up/down position?

[aletorno]

why do you use ls7184 if the dspic allready have quadrature encoder interface?