Transcript Slide 1
Improved Robotic Arm and Turntable for Sensitivity Characterization of Occupancy Sensors Turntable Team Sam Garza Anne Killough Bob Ramenofsky Havan Tucker Robotic Arm Team Will Hedgecock Brian Auerbach John Sullivan Sponsor Information • Square D produces wall switch occupancy sensors • Senses when room is occupied and switches light on/off correspondingly • Uses ultrasonic and PIR sensing technology • Saves energy by minimizing unused light • Detects major motion in rooms up to 1000 sq. ft. Project Description • Improve current testing procedure • Currently takes a minimum of 7 hours to test one sensor • Testing requires 1000 sq. ft. room • Arm does not radiate with IR spectrum similar to that of a human arm • Automate testing procedures to minimize user intervention • Emit IR spectrum similar to that of human arm • Provide more stable arm • Less “jitter” when starting/stopping • Can be held in any position for over an hour Current Testing Procedure Simulate the testing room by rotating the sensor and setting the robotic arm at various locations in the coverage pattern. (Measurements in feet) Operational Concept System Design Requirements Turntable • Sensor mounted exactly 48” above floor • Sensor capable of ± 90 ° rotation at a resolution of .5 of a degree • Portable and Durable Robotic Arm • • • • • Arm must be 18” long with 15” heated Must be mounted 36” above the ground Must be heated between 80-120 degrees Fahrenheit Peak wavelength emitted 9.4um with a range of 7-15um Must move 180 degrees horizontal and vertically, but not simultaneously • Must move through 90 degrees of an arc per second Command and Control Interface Turntable Controls Robotic Arm Controls Automated Testing Grid Control Protocol Robotic Arm Protocol: ASCII Character Decimal Value Vertical Up Vertical Down Horizontal Right Horizontal Left New Speed U D R L S 85 68 82 76 83 Turntable Protocol: ASCII Packet Rotate R Sensor On ON Sensor Off OFF Acknowledgement ACK Hexadecimal Value 55 44 52 4C 53 Functional Flowchart Microcontroller Overview • NetBurner MOD5272 Development Kit: • Motorola MFC5272 Microcontroller • NetBurner MOD5272 Development Board • NetBurner Embedded Ethernet Core Module • 2 Serial Ports • 4 Timers • General Purpose I/O Ports (50 pins per header) • 32-bit processor Robotic Arm Assembly Overview Robotic Arm Operational Flowchart Robotic Arm Firmware • Initializes microcontroller’s IP address via DHCP • Sets up a listening socket on port 24321 • Accepts an incoming TCP connection from the Command and Control Assembly • Receives control packets from the Command and Control Assembly • If microcontroller receives an ‘S’ packet, it parses the integer value in rest of packet and sets the speed of motion of the arm to traverse this integer number of degrees per second • If microcontroller receives a ‘U’ or ‘R’ packet (Up or Right), the direction pin is set to high, else low Robotic Arm Firmware (continued) • Controls robotic arm motion via pulses from two GIOP pins on the microcontroller • Stepper motors require 500 steps to rotate 90° of an arc and stepper controllers cause motors to step once on every falling edge of a pulse from the microcontroller • Using the internal timing system of the microcontroller, interrupts are generated every 1/500th of a second • If motion is desired, every interrupt sends a pulse to the stepper controller until 500 steps have been made Infrared Background Information Thermal Element Specifics 4 Silicone Rubber Heaters 4 Solid State Relays 1 OMEGA 1504 Multiloop PID 1 120VAC Variable Transformer 1 Roll of Electrical Tape Thermal Proof of Concept Mechanical Design Problems Last Year’s Design Problems: • Arm diameter below NEMA requirements • Arm length below NEMA requirements • Low Torque • Constant Shaking Solution: • Direct Drive Stepper Motors • Open Loop System • Arm to correct specs Turntable Assembly Overview Sensor on oti n ll M tio Ce rifica Ve Power Supply Sensor Circuitry Turntable Assembly Microcontroller Motor Angle and Sensor Data Command and Control Signals Servo Motor Sensor Data Power Supply PC Robotic Arm Assembly Turntable Firmware Responsibilities • Maintain communications with the computer • Control the servo motor • Keep track of the status of the relay Maintaining Communications with the Computer • • • • • Using DHCP to automatically assign an IP address Initializes the TCP/IP stack Listen for TCP connections on 24321 and 24322 Wait until connections are established Pass control to the main OS task Turntable Firmware (continued) Control the Servo Motor • Using the timer system to scale down the clock • Output compare to match our timeout values • First a timeout value is set for the high part of the square wave • After this timeout, a value is set for the low portion of the square wave • This creates a 33 ms period of variable duty cycle Keep Track of the Status of the Relay • Utilizes the same timer system that controls the servo motor • When the relay state changes, sends a TCP message to the controlling computer Turntable Hardware Motor • • • • Hitec HS645MG servo motor 107 oz-in. of torque at 4.8 V Dual ball bearing design Weighs 1.94 oz. Sensor Mount • Indoor single gang box • PVC construction Cart • Buhl BAV-4226C compact AV cabinet cart • 42’’ tall Results All requirements met! See final assembly for physical results of project.