Case-New Holland

Steer-by-Wire Detailed Design

Today’s Agenda

Who is CNH? Background Project Goal System Level Concept Design Components Detailed Concept Validation of Concept Superiority Resources and Cost Summary of Results What’s Next?

Who is CNH?

One of the world leaders in Agricultural Equipment.

Various locations world wide.The Technical Center is located in New

Holland, PA.

Background

The system is currently a purely mechanical linkage from operators hand to hydrostatic pumps.

Current Steering System

Project Goal

Goal is to remove mechanical linkage and replace with a lower cost,

expandable, steer-by-wire system

Why Steer By Wire?

Can customize software to specific needs– Future possibility of GPS

navigational driving

Removal of expensive mechanical linkage Less component wear and

tear Lowers manufacturing

cost

System Level Concept and Project Scope

Steering Column

Sensor: Reads Angular

Displacement

ECU

2 Independent Output Channels

Power Source

Pumps

Wheels

Project Scope

Customer Wants

Key Metrics

1.) Production Price: < $90.00

2.) Accuracy: ± 1°

3.) Resolution: ± 0.5°

4.) Temperature Range: -40° - 180° F

Concept Components

Mounting Location Sensor Selection Shaft Extension Design

To hold sensor and viscous damper Mounting Bracket Design

To incorporate a “real-feel” and prevent CNH from having to heavily modify our design at a later time, we will integrate a viscous damper into our design.

System Concept

Mounting Location

Below Cab Least structural

alterations to steering column structure

Most serviceable Exposed to elements Limited depopulation

Boot Minimal structural alterations to

steering column structure Least space restrictions May be prone to vibration

Top Knuckle Maximum depopulation Completely encased in

the steering column Will require significant

structural alterations Limited room for

mounting

Mounting Location

BootMinimal structural alterations to

steering column structureLeast space restrictions

Sensor Selection

Proximity: Possibility of machining a cam or screw onto

shaft and measuring distance to decipher turning degrees

Magnetic Hall EffectEnd Mount

BEI Duncan Electronics’ 9900 Series Dual Output Hall Effect Sensor

Feed-Through MountDelphi’s Non-Contact Multi Turn Rotary

Position SensorBEI Duncan Electronics’ Non-Contacting

Angular Position Sensor (NCAPS).

Sensor Selection

Due to time and cost issues, the Non-Contacting Angular Position Sensor (NCAPS) currently in production will be used for the prototype. Current NCAPS does not meet redundancy requirement,

however, for production a custom made sensor that meets all requirements will be used.

BEI Duncan design engineers are currently working on the design of this custom sensor

BEI Duncan NCAPS

Shaft Extension

Material: Aluminum 3/8” diameter with ¼” flats. End will be machined down to 5/16” and force fit into the

splined end of the current shaft with a roll pin that will ensure rotational unison.

Sensor will have a Collar that will adapt to the 3/8” shaft.

Detailed Design of Shaft

Shaft Extension

Performed a Finite Element Analysis (FEA) on the shaft using SolidWorksDetermined that the shaft will have a static

displacement of 7x10-5 inches and an angular displacement of 9.408x10-5 degrees in maximum torsion at the end of the shaft.

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Justification

Mounting Bracket

Material: Alloyed Steel Purpose of Bracket is to secure

sensor and damper to steering column

2 piece Mounting Bracket First Holds the Damper in place Second Holds the Sensor in place

Secured with four bolts to steering column framework

Detailed Design of Mounting Bracket

Viscous Damper

The damper will add the “real-feel” desired for the steering system.

Safely and quietly controls rotary motion (0.4 – 4.5 Nm.) of Torque per unit is available Maximum Torque experienced will be

approximately 2 Nm

Validating the Concept

A prototype was built using components designed by the Senior Design team and supplied by CNH

Tested with Labview software Output signal from sensor compared

with the output of a “Truthing Sensor” Optical Encoder was used as the

“Truthing Sensor” The Prototype will eventually be

installed into CNH Windrower for on track test!!!

Test Data

• First graph shows the output of the sensor and encoder vs. time.

• Second graph shows the difference between the two outputs

• Third graph shows the derivative of the BEI sensor output.

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BEIEncoder

Test Data Analysis

From the data we determined that there is a difference of approximately ±5° between the two sensors when there is rotation.

There is a consistent error in the same portion of each revolution which leads us to believe that there are imperfections in the shaft alignment. Testing of run out with a dial indicator

located where the sensor is positioned on the shaft showed 0.02” TIR.

Testing of run out with a dial indicator located directly after the last bearing showed .001” TIR.

Through testing of relative angle change resulting from linear displacement of the Rotor we found that there is an error of 1°.

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Resources

CNH BEI Sensor for

prototyping

Fabricated bracket for mounting of sensor

Testing of prototype for temperature requirements, reliability, drift, and EMC

Senior Design Team Building of Prototype

Steering Column

Testing of resolution, repeatability, and accuracy were done using UofD PC running Lab View

Prototyping Cost

Sensor for Prototyping: $300.00 Sensor for CNH Preliminary testing: $300.00 Mounting Stand: $45.00 Shaft Extension: Freebee Bracket for mounting Sensor: $10.00 Truth Sensor: Freebee CNH Testing: $17,500.00 est. Miscellaneous Hardware: $10.00

Total Estimated Cost$19,000.00

Estimated Unit Production Cost

• Sensor: $70.00 est.• Shaft Change: $5.00 est.• Brackets for mounting Sensor: $5.00 est. • Miscellaneous Hardware: $5.00 est.• Steering Column Depopulation: ≈-$10.00 est

Total Estimated Unit Cost$75.00

CNH Target Unit Cost$90.00

System Performance vs. Metrics

Metric Target Results

Unit Price $90 $75

Accuracy ±1° ±2.5°

Resolution ±0.5° ±2.5°

Temperature ±0.5° TBD by CNH

Path Forward

Turnover of prototype and project to CNH

Design interfaced with servo motor to pump project

Safety and track testing

Ongoing conversation with BEI for custom sensor delivery

In Conclusion...