Improved Robotic Arm for Sensitivity Characterization

of Occupancy Sensors

Will HedgecockBrian Auerbach

John Sullivan

Project Requirements

• Controlled movement through 90° of an arc in one second

• Vertical and horizontal movement, but not simultaneously

• Arm mounted exactly 36” above floor surface on a movable cart

• Remote control (>50 ft.) via a PC

• Exactly 15” of heated area on an 18” arm

• Adjustable temperature control with the range 80 to 120 degrees Fahrenheit, accurate to within 2 degrees Fahrenheit

Previous Project Problems

• Heating element did not emit IR waves within a satisfactory range of an actual human arm

• Heating element did not emit IR waves uniformly through space

• Robotic arm shook violently when starting and stopping movement

• Servo motors overheated when holding robotic arm at 90° angle with floor for an extended amount of time

• Robotic arm did not always respond to UI key presses, resulting in the necessity of multiple key presses to create robotic arm movement

New Project Improvements

• Use of heating element which emits in the proper IR range, matching that of a human arm

• Implementation of heating element such that there are no gaps spatially in the emitted IR waves; i.e. must emit uniformly

• Use motors with enough torque to start and stop motion of robotic arm without jerking or causing other undesired movements

• Use motors which will not overheat when holding the robotic arm at 90° for an extended period of time

• Ensure that key/button presses will always result in the intended motion of the robotic arm

Heating Options

IR-Emitting LEDs

Spray-On Emitter

Tungsten Wire

Infrared LEDs

• Extremely directional

• Emits IR wavelengths on the scale of nanometers• We require micrometers• Human IR emission ≈ 9.4

μm

• Difficult to arrange cylindrically such that they emit a uniform IR spectrum, leaving no gaps between emissions

Tungsten Wire

• Must be EXTREMELY hot in order to emit in necessary IR range

• Moderately priced

• Can be wrapped around a cylindrically-shaped arm

• Easy to “kink” wire, causing it to break

Spray-On Emitter

• Easy to apply to arm

• Possibility of needing re-applications

• Needs to be researched more

Motor Advantages/Disadvantages

Servo Motors Stepper Motors

Constantly actuated Position stable

Less torque More torque

No position holding mode

Easy position determination & holding

Microcontroller Requirements

• Must output appropriate voltage to drive stepper motor drivers

• Must have enough outputs to drive horizontal and vertical motors, as well as motors for Turntable project

• Must have an Ethernet-capable receiver/transmitter as well as a UART for connections to/from robotic arm and/or turntable

• Must be programmable to be interrupt-driven

• Possibility: PIC18F97J60Memory Type

Program Memory

RAM I/O Pins

Pin Count

CPU Speed

Digital Communications

Ethernet Timers Operation Voltage

Flash 128 kB 3808 70 100 42 MHz 2 USART2 MSSP

10Base-T 2 x 8-bit3 x 16-bit

2V – 3.6V

Tentative Schedule

ID Task Name Duration Start Finish Predecessors

1 Project Start 1 day Mon 10/15/07 Mon 10/15/07

2 Mechanical Design 39 days Sun 12/9/07 Wed 1/30/08

3 Arm Development 39 days Sun 12/9/07 Wed 1/30/08

4 Specify Arm Dimensions & Torque 1 day Sun 12/9/07 Mon 12/10/07 1

5 Create Arm Mechanical Drawings 1 day Tue 12/11/07 Tue 12/11/07 4

6 Choose Motors 3 days Sun 12/9/07 Wed 12/12/07 1

7 Choose Materials 2 days Wed 12/12/07 Thu 12/13/07 1

8 Procure Parts & Materials 10 days Fri 12/14/07 Thu 12/27/07 5,7

9 Construct Arm 2 days Mon 1/14/08 Tue 1/15/08 8

10 Attach Arm to Cart 1 day Wed 1/30/08 Wed 1/30/08 9,16

11 Cart Development 13 days Mon 1/14/08 Tue 1/29/08

12 Specify Dimensions & Requirements 1 day Mon 1/14/08 Mon 1/14/08 5

13 Create Cart Mechanical Drawings 1 day Tue 1/15/08 Tue 1/15/08 12

14 Choose Cart 1 day Wed 1/16/08 Wed 1/16/08 13

15 Procure & Modify Cart 1 day Mon 1/28/08 Mon 1/28/08 14

16 Assemble Cart 1 day Tue 1/29/08 Tue 1/29/08 15

10/15M T W T F S S M T W T F S S M T W T F S S

Sep 30, '07 Oct 21, '07 Nov 11, '07 Dec 2, '07 Dec 23, '07 Jan 13, '08 Feb 3, '08 Feb 24, '08 Mar 16, '08

Tentative Schedule (cont.)

ID Task Name Duration Start Finish Predecessors

17 Electrical Design 28 days Sun 12/9/07 Wed 1/16/08

18 Choose Microcontroller 3 days Sun 12/9/07 Fri 12/14/07 6

19 Choose Power Supply 1 day Fri 12/14/07 Mon 12/17/07 6,18

20 Create Functional Diagram 1 day Fri 12/14/07 Mon 12/17/07 18

21 Procure Parts, Cables, and Tools 10 days Mon 12/17/07 Mon 12/31/07 20

22 Assemble Circuits and Electronics 3 days Mon 1/14/08 Wed 1/16/08 21

23 Heater Design 38 days Wed 11/28/07 Fri 1/18/08

24 Choose Heating Element 15 days Wed 11/28/07 Tue 12/18/07 1

25 Choose Control Interface 2 days Wed 12/19/07 Thu 12/20/07 24

26 Procure Parts & Materials 10 days Fri 12/21/07 Thu 1/3/08 25

27 Assemble Heating System 1 day Mon 1/14/08 Mon 1/14/08 26

28 Install Heating System 3 days Wed 1/16/08 Fri 1/18/08 9,27

29 Software Design 80 days Tue 10/16/07 Fri 2/1/08

30 Choose Microcontroller Language 1 day Wed 12/19/07 Wed 12/19/07 18

31 Choose Microcontroller Compiler & Tools 1 day Thu 12/20/07 Thu 12/20/07 30

32 Choose GUI Language and Development Tools 1 day Tue 10/16/07 Tue 10/16/07 1

M T W T F S S M T W T F S S M T W T F S SSep 30, '07 Oct 21, '07 Nov 11, '07 Dec 2, '07 Dec 23, '07 Jan 13, '08 Feb 3, '08 Feb 24, '08 Mar 16, '08

Tentative Schedule (cont.)

ID Task Name Duration Start Finish Predecessors

33 Define Necessary Functionality 1 day Tue 10/16/07 Tue 10/16/07 1

34 Design GUI Layout 1 day Wed 10/17/07 Wed 10/17/07 32

35 Write GUI Code 15 days Thu 10/18/07 Wed 11/7/07 34

36 Write Microcontroller Code 10 days Sun 1/20/08 Thu 1/31/08 31

37 Implement Microcontroller Code 1 day Fri 2/1/08 Fri 2/1/08 36,21

38 Testing 32 days Sun 1/20/08 Sun 3/2/08

39 Test Arm 1 day Wed 2/6/08 Wed 2/6/08 10

40 Test Code 1 day Mon 2/4/08 Mon 2/4/08 35,37

41 Test Heating System 1 day Sun 1/20/08 Sun 1/20/08 28

42 Create Test Environment 5 days Mon 2/18/08 Fri 2/22/08 1

43 Test Final Prototype 1 day Sun 3/2/08 Sun 3/2/08 39,40,41,42

44 Documentation 5 days Sun 3/9/08 Thu 3/13/08

45 Mechanical Documentation 5 days Sun 3/9/08 Thu 3/13/08 10,16

46 Electrical Documentation 5 days Sun 3/9/08 Thu 3/13/08 22

47 Software Documentation 5 days Sun 3/9/08 Thu 3/13/08 35,36

48 Heating Documentation 5 days Sun 3/9/08 Thu 3/13/08 28

49 Project Complete 1 day Fri 3/14/08 Fri 3/14/08 43,45,46,47,48 3/14

M T W T F S S M T W T F S S M T W T F S SSep 30, '07 Oct 21, '07 Nov 11, '07 Dec 2, '07 Dec 23, '07 Jan 13, '08 Feb 3, '08 Feb 24, '08 Mar 16, '08