Student Projects
Contact Information
University and Department: King Abdulaziz University, Production Engineering and Mechanical Systems Design Department
Team Members: Abdullah Algethami
Primary Email Address: a_algethami@hotmail.com
Primary Telephone Number (include area and country code): +966-506354615
Project Information
List all parts (hardware, software, etc.) you used to design and complete your project:
NI USB 6008 DAQ®
NI LabVIEW ™ 8.6 Student Edition
Describe the challenge your project is trying to solve.
Robotics lab has five degrees of freedom table top size articulated robot. It can be controlled through three methods; teach pendant, tape record and DOS software. The last two methods cannot be used because software is obsolete. The teach pendant run motors manually which is very simple, unfortunately the robot wasn’t an efficient tool for teaching students about robotics.
Describe how you addressed the challenge through your project.
The Solution:
To built low cost PC-based program by using NI LabVIEW and NI USB 6008 to control the robot. Simple user friendly robot program can be developed to run the robot in a manual and automatic way. After completing this project robot will serve at robotics lab for teaching and experiments, so students can write their own programs on LabVIEW to control the robot.
Abstract
The robot is using old technology which is a tape recorder, and also needs an external computer with DOS software. Teach pendant can also be used which is not easy to use for teaching students robotics applications and control concepts. Using NI products hardware and software have the advantage for replacing any instrument by virtual one in Lab VIEW. Replacing the teach pendant by NI USB 6008, and using Lab VIEW allow for building easy program for controlling the robot. More programs can be developed by students later. Using the NI products make it easy to reach the goal and save time.
Introduction
Atlas Robotic system made for educational purposes. Robot can be classified as polar robot. It has five degrees of freedom actuated by five stepper motors which are arm rotation, arm elevation, arm extension, wrist elevation and wrist rotation, and there is one more function which is a closing or opening of the jaw. Robot’s work based on 6502 microprocessor and having 6k of EPROM capacity for the control programs and 8k batterybacked RAM for sequence data storage.
There are three ways to control the robot through; teach pendant, DOS Software running by external computer and tape recorder to save the programs to use again due to low RAM space.
Teach pendant is an external switch pad which can be used to direct the robot through a sequence of movements. It provides three speed settings, push-button forward and reverse drive switches for each movement function, and set reference pushbutton to set a secondary reference in the microcontroller. The teach pendant connected to the Atlas Robot base by 34-way ribbon cable.
Replacement Teach Pendant by NI Hardware
The NI USB-6008 is a USB based data acquisition (DAQ) and control device with 8 channels analog input and 2 channel analog outputs and 12 digital input and output.
The main advantages of NI USB-6008 are low cost device and portable, so any student can buy it, and make his programs, then coming to the lab to connect and try it with the system as shown in Figure.1 Teach pendant is chosen to be replaced, because it is separate from the main board, its circuit is clear, simple and all switches work with digital 5 volt. Fortunately all its switches can be done directly from NI USB 6008 to replace the entire switch by digital signals, 18 digital lines required. But 14 signals can be enough if stepper motor speed accepted as a default speed. The other circuits kept as it is and grouped in the interface unit. Teach pendant cable disconnected and a new cable coming from the NI USB 6008 and interface unit connected instead. The teach pendant can be kept as it is and can be used later.
Figure.1: The robot with NI product replacing old controller
NI LabVIEW Control Software
Advanced program other than a simple manual mode operation can also be build easily. Figures 2 and 3 show an example that can be used. User can define a sequence of motions and define distances in [cm] or [deg]. User can put unlimited number of sequences and should end the sequences by an “end” operation. When the user presses the “run” button; the program will start the execution. The total running time required to execute all the sequences will be shown, which sequence is running at the moment will also be shown.
If the teaching pendant method is wanted to be used, same functions done by the real teach pendant was simulated in the manual mode operation. When the pushbutton pressed actuates the stepper motor, when released stepper motor stops. When a pushbutton pressed a digital signal send through the NI USB 6008 to the robot base circuit, which is similar to how the real teach pendant works.
Figure.2: Front Panel of the main VI while driving the robot through some sequences
Modular programming which is built as subroutine in other languages give more flexibility in programming by LabVIEW. User can think to build a program for each function of the main program in separate VI, then all VIs used in the main VI.
Figure.3: Block Diagram for the Robot Control VI using LabVIEW
Results and Conclusions
Using NI USB 6008 DAQ and NI LabVIEW ™ 8.6 Student Edition, table top size five degrees of freedom robot is controlled through computer. One can operate the robot by selecting infinite number of sequences of each freedom. Teach pendant operations also simulated on the computer as a manual mode.
