Pan-Tilt Signature System

Pan-Tilt Signature System

Pan-Tilt Signature System Rob Gillette Matt Cieloszyk Luke Bowen Final Presentation

Introduction Problem Statement: We proposed to build a device that would mimic human script using a pan-tilt system. Motivation The development of this system would require work in many fields relevant to control systems design while remaining within the limited scope of the class. The system would be relatively unique and fill a void in the high-tech consumer market.

Objectives Recreate unique human script using a customized trajectory based on handwriting. Develop a robust, accurate, reliable controller able to deal with the large disturbances present in our system. Develop a unique system with possible future market value.

Specifications Range of motion Speed: 7x7 inch canvas Pan and Tilt: +/- 45 deg (+/- 0.7853 rad) Cover 7 inches in 1 second Pan and Tilt: 7 in/sec (1.5707 rad/sec) Rise time and Settling time: <0.3 seconds

Specifications Error Steady State Error: minimal The pen must reach the desired input for script to be clearly legible. Ideally S.S. error < 1% Tracking error: minimal however we are tracking a custom trajectory so there is some flexibility. Ideally Tracking error <2%

Design Strategy Our project was built through the simultaneous completion of three phases. Mechanical Design Phase Simulation and Modeling Phase Control Design Phase

Mechanical Design Phase Replaced original encoders Original HP encoders Missed counts at middle to high velocities Located on motor shaft, thus did not account for deformation or disturbances New Encoders Double resolution: 2048 vs. 1024 Located on output shaft

Mechanical Design Phase Pen Mount A spring loaded pen mount was constructed from machined aluminum and mounted on the tilt axis. Designed to hold a Sharpie marker. Contained housing for lightweight spring and accommodation for possible servo motor enhancements

Mechanical Design Phase Aluminum Pen Mount

Mechanical Design Phase Writing Surface A writing surface was constructed using wood and metal braces. A sturdy paper backing was used to prevent the marker from bleeding through. The surface is free to rock on its base to reduce high levels of friction during operation.

Simulation and Modeling Phase Motor Feasibility We ran point to point control using a preliminary controller and an estimation of friction to determine if our motors were adequate. m otor 1 velocity (rad/s) 500 450 400 350 300 250 200 Pittman GM8724S010 not feasible m otor 2 velocity (rad/s) 500 450 400 350 300 250 200 Pittman GM8724S017 not feasible Torque requirements fell within the ranges of the motors. 150 100 50 feasible 0 0 0.01 0.02 0.03 0.04 0.05 motor 1 torque (Nm) 150 100 50 feasible 0 0 0.01 0.02 0.03 0.04 0.05 motor 2 torque (Nm)

Simulation and Modeling Phase Pan Axis Velocity Curves 10 8 6 4 Pan Velocity Curves 2 Voltage input from -1v to +1v 0 Velocity 0-2 -4-6 -8-10 5 10 15 20 25 time

Simulation and Modeling Phase Pan Friction ID Viscous -0.0061 0.0048 Coulomb -0.1438 0.15802 applied torque (N-m) 0.25 0.2 0.15 0.1 0.05 0-0.05-0.1-0.15-0.2 Coulomb Friction: -0.14386,0.15802 Viscous Friction: 0.0061749,0.0048541 friction identification data- Tilt Axis -0.25-10 -8-6 -4-2 0 2 4 6 8 10 steady state theta dot (rad/s)

Simulation and Modeling phase Tilt Axis Velocity Curves 10 8 6 4 Tilt Velocity Curves 2 Voltage input from -1v to +1v velocity 0-2 -4-6 -8-10 0 5 10 15 20 25 time

Simulation and Modeling Phase Tilt Friction ID Viscous -0.00958 0.00914 Coulomb -0.16056 0.17353 applied torque (N-m) 0.3 0.2 0.1 0-0.1-0.2-0.3 Coulomb Friction: -.16056,.17353 Viscous Friction:.0095845,.0091431 friction identification data -0.4-10 -8-6 -4-2 0 2 4 6 8 10 steady state theta dot (rad/s)

Simulation and Modeling Phase Open Loop Model Developed using physical parameters of system: mass, inertia, COG, friction, motor specs, etc. velocity 10 8 6 4 2 0-2 -4-6 -8 Tilt Model Verification -10 0 5 10 15 20 25 10 8 6 4 time Pan Model Verification 2 velocity 0-2 -4-6 -8-10 0 5 10 15 20 25 time

Simulation and Modeling Phase Closed Loop Model Parameters from the open loop model were used in developing a closed loop model.

Control Design Phase Identification of pan and tilt transfer functions for use in RLTOOL Gtilt(s) ) = (31.08)/(s^2+2.35s) Gpan(s) ) = (21.08)/(s^2+2.34s+1.8)

Control Design Phase Gtilt(s) was imported to RLTOOL. 2 poles and 2 zeros used

Control Design Phase Step response of tilt axis Rise time = 0.05 sec Settling time = 0.07 sec

Control Design Phase Gpan(s) was imported to RLTOOL. 2 poles and 2 zeros used

Control Design Phase Step response of pan axis Rise time = 0.05 sec Settling time = 0.06 sec

Control Design Phase Gtilt(s) was imported to RLTOOL. 1 pole and 2 zeros used

Control Design Phase Step response of tilt axis Rise time = 0.05 sec Settling time = 0.09 sec

Control Design Phase Gpan(s) was imported to RLTOOL. 1 pole and 2 zeros used

Control Design Phase Step response of pan axis Rise time = 0.06 sec Settling time = 0.1 sec

Control Design Phase Summary of RLTOOL results The compensators achieved with 1 pole and 2 zeros were deemed adequate. The advantage being that PID gains can be easily obtained from the form of C(s) TILT AXIS: Kp = 3.01, Ki = 1, Kd =1.275 PAN AXIS: Kp = 4.065, Ki = 1.5, Kd = 1.683

Control Design Phase Controller tuning RLTOOL gains were placed into actual control system and performed well. Ki and Kd were very good, Kp needed to be increased. TILT AXIS: Kp = 55, Ki = 0.88, Kd =1.2 PAN AXIS: Kp = 60, Ki = 0.98, Kd = 1.95

Results We developed several scripts to test various pan and tilt motions for accuracy. The following slides show graphs of desired and actual trajectories during operation.

Results Square demonstrates independent pan and tilt motion

Results Star demonstrates diagonal motion

Results Circle demonstrates tracking of sin waves

Results Signature demonstrates complete realization of project goals.

Conclusion We believe we accomplished the goals that we set forth in the beginning of the semester Our machine is capable of accurately reproducing any signature it is given Our machine is simply built, durable, reliable, and cost effective Our machine is unique and holds possible market value given more time for development.

Conclusion Possible Enhancements There are considerable disturbances that could be dealt with through more thorough mechanical design. Motion of pen Motion of writing surface A servo was going to be incorporated into the machine to give the ability to remove the pen from the canvas.

Servo Driven Pen Movement Operates off of a Pulse Width Modulated signal Many ways to send the signal, most common being a 555 timer Powered by a 6v source Range of motion ¾ one way, 1 ½ full

Servo Driven Pen Movement Pen movement needed to create some characters Servo able to pull and push the pen Planned on connecting via a wire and spring for gear safety

Future Plans Incorporate the servo into the design Program servo movement into existing designs currently possible by the machine Create new output designs for the machine and controller to handle Continually fine tune the controller

Conclusion Costs We successfully kept our project well under our allowed budget Schedule We successfully completed our schedule with only minor adjustments

Schedule Analysis February Simulations and Gather Gains and Motor Feasibility CAD Drawings and Physical Properties, Order Parts March Gains, Motor timing Testing Part Fabrication and Mounting April Software Testing and Tuning Hardware Testing and Tuning Final Presentation and Report

Schedule Analysis February s goals might have overstepped with regards to modeling March was used to finish modeling, friction id, and experimentation April s deadlines were met Overall the schedule was reasonable and a helpful guideline

Conclusion Questions?