Using Pulse-Width Modulation Fluid Power Control

The Team Andy the Red Ranger Shelley the Blue Ranger Anna the Yellow Ranger Robert the Green Ranger Nathan the Black Ranger Jack the Pink Ranger Alex the White Ranger J. Newlin – The Science Museum of Minnesota Forrest Price – The Science Museum of Minnesota Professor William Durfee – The University of Minnesota Professor Perry Li – The University of Minnesota

World… meet Fluid Power

Goals Explain Fluid Power to the Public Connect PWM and Fluid Power Explain the New Research Done by the University Have 3 Interactive and Educational Exhibits Have At Least One Site Visit to the Science Museum Before Design Show Have Multiple Levels of Complexity

Exhibits Fluid Power Experiment Bench “Build It Yourself” Hydraulic Circuits PWM and Duty Cycle Test Bed Both Electrical and Hydraulic PWM Circuits Hydraulic PWM Valve Poster and Prototype Working Model of PWM Valve

Science Museum Exhibit Basics What makes a good exhibit? Educational Engaging Appeal to many age levels Multiple users Multi-sensory Visible moving parts Explanation/Exploration of familiar phenomena Average time a person spends at an exhibit is 2-3 minutes!

Experiment Bench One concept Several variables, many outcomes Do it yourself Early assured success (EAS) One to three users Ownership

Fluid Power Experiment Bench Concept: Fluid Power Variables: dump truck, sprinkler, carousel, valves and pumps Users plumb it themselves EAS: simple circuit Designed for 1-3 users Ownership: jelly bean shaped bench

Fluid Power Experiment Bench Our vision

Base Circuit and Loads

The Experiment Bench Prototype Landscape tubing Working Exhibit Clear PVC Clear tubing

PWM Demonstration Make workings of PWM visible to viewers Demonstrate Improved Efficiency Compare similar usage of PWM in an Electrical and Fluid circuit

Electrical Demonstration Demonstrate PWM with two light dimmers Power Source – Hand Cranked Generator Load – Light Bulb PWM Signal generated by large optical encoder Comparison in energy usage: Power resistors vs. Power semiconductors Visitor will feel difference in power demands

System Layout

A Second Identical Exhibit Make a parallel exhibit using fluid components: Generator → Pump with reservoir Resistors → Throttling valves Transistors for PWM → High speed solenoid valve Light bulb → Fan connected to fluid motor Power meter → Tachometer Switching transistors → 3-way solenoid valves

Fluid Circuit

User Inputs for Both Exhibits A start button Spins the duty cycle wheel for 30 seconds Crank The user can spin the crank to deliver power Toggle switch Activates duty cycle or divider/throttler system Load power selector Varies the duty cycle and selects divider/throttler

The Activity 1. Hit start to spin wheel 2. Turn crank to deliver power 3. Switch between the parallel systems 4. Repeat at different duty cycles 5. Watch the system as the wheel slows down

Desired Results Understanding of PWM power efficiency User gets brighter bulb / faster fan using PWM system for a given power input Understanding of electrical and fluid power The user feels the power input and sees the output Understanding of pulse-width modulation The dim bulb becomes a flashing bulb at the end Fun and interactive The user enjoys experimenting with the exhibits

Current Design Designed for user accessibility Users of 40 to 70 inches tall Wheelchair accessible Designed for user friendliness Few user inputs Exhibits are back-to-back

Dimensions (inches) Current Design

UMN Research Poster Inform Improvements Control Pump optimization Display

Purpose of the Project Relay Knowledge Common Applications of Fluid Power and PWM Current Research at the University of Minnesota Encourage Interest Theories of PWM and Fluid Power Control Attraction of Target Group Attract a 4 th Grade Audience Hold Attention of Target Audience

Review Three Exhibits Fluid Power Experiment Laboratory PWM Electrical Portion Fluid Portion Poster and Model

Tasks Left to Complete Fluid Power Experiment Lab PWM Exhibit Poster/Model Science Museum Testing Adjustments to the Exhibits Before the Design Show