Electronic Power Steering Bench Test Fixture Written by: Chapin Griffith January 10th, 2014

Chassis Systems Engineering Intern, Sep 2013 – Jan 2014 B.S. in Engineering Mechanics, focus in Automotive Mechanics University of Illinois at Urbana-Champaign, May 2014

Purpose: The EPS bench test fixture has been created to aid in research of potential power steering gears for GEN III cars. The power steering gears we have been focusing on are the ZF Ball Screw type (also called the JLR gear because it is used by Jaguar-Land Rover, and is the gear currently used in the Model S), NSK pinion type, Mando blank type, and the Daimler Ball Screw type (also made by ZF, but supplied to Daimler, will be used in Model X). These four steering gears vary in price from $450/unit to $750/unit, so it is desired to test each gear on an A to B to C, etc. comparison to determine which gear best fits the GEN III needs. This decision is not necessarily made by which gear performs the best in all categories; a lower performance gear may satisfy the needs of GEN III and be less expensive, thereby being the correct choice. Thus, we encounter two goals: determining the requirements of GEN III steering, and evaluating each gear against these requirements. “Perfect Steering”: Some work has been done in determining the GEN III requirements, but it is ongoing. (I should preface this section by encouraging you to modify these requirements as testing begins and more is learned about quantifying “perfect steering”) In my mind, we should start by qualitatively and quantitatively describing “perfect steering,” and then decide how far from this the GEN III steering can deviate. Power steering can be characterized by two basic platforms: the correlation between steering wheel angle and vehicle wheel angle (rack position), and the amount of assist you get from the power steering motor at a given point in time. In a perfect steering system, an exact correlation will exist between steering wheel deflection from center, and rack position from center, which is dictated by the C-factor (circumference factor) of the steering gear. The C-factor is measured in millimeters per revolution, and is, for example, 66.5 mm/rev on center, and 72.6 mm/rev off center. What this means is that on center, the rack will move 66.5 mm with one revolution of the steering wheel, which gives the steering a responsive feel that allows you to make small changes. But off center, the rack will move a larger distance with one revolution of the steering wheel which is ideal when you are trying to make a U-turn, turn into a parking space i.e. get the wheels turned hard. Now we have our first requirement…

Requirement #1: The C-factor of the steering gear, on center, must be (blank), and off center, must be (blank).

The C-factor requirements have been left blank because the values have not been determined yet. In-vehicle testing is required to determine a small enough C-factor on center to be able to make small changes to the vehicle wheel angle under heavy cornering, but large enough off center to not be cumbersome to get the car turned around. Also, keep in mind that the C-factor is not always different from on center to off center. The second requirement is related to what has been stated previously, namely that the correlation between steering wheel angle and rack position angle must be exact, as dictated by the C-factor. Requirement #2: The loss of coherence may not exceed (blank) at any time during all types of normal driving. This correlation is also called coherence, and the value has been left blank because testing is required to determine the maximum allowable loss of coherence. There a few things that can break down coherence between the two variables. Mechanical compliance anywhere in the system will lead to loss of coherence, and the torsion bar is a compliant component inherent to electronic power steering systems. As you turn the steering wheel, the torsion bar twists and deflects in small displacements that are sensed by a twist angle sensor and the power steering motor supplies torque assist based on these displacements. However, there is naturally a delay, and if the steering input is fast and dynamic, there will be a delay of torque assist from the motor and therefore a loss of coherence between the steering wheel and rack position.

These graphs were taken from in vehicle testing of a car doing a “frequency sweep.” The x-axis is time, and the y-axis is steering wheel position for the top graph, and rack position for the bottom graph. The driver turned the wheel with a fairly constant 35 degree amplitude, increasing the frequency to as fast as he could, then decreasing the frequency again. As you can see, the steering wheel’s travel remained about the same throughout the test; however the rack’s travel did not. As the amplitude increased, the coherence between the rack and steering wheel decreased dramatically. In one cycle, the rack hardly moved at all, and this is a clear demonstration of how mechanical compliance can lead to loss of coherence. Another compliant component is the coupler in the lower I-shaft of the steering shaft, in between the steering gear and the steering wheel. This coupler is a strong rubber piece that puts a slight delay between the driver’s steering input and the change of angle of the vehicle wheels. This is purely for driver comfort; without the coupler, the car feels like it is turning ahead of you, because it steers from the front. With a small delay, the steering feels more central to the car, as if you are steering yourself, and not the front end of the car. Requirement #3: The coupler piece must put a (blank) delay in steering response. This requirement has been left blank because in vehicle testing is required to determine the appropriate delay so the steering “feels” right. The other platform that characterizes power steering is the torque assist given from the power steering motor. This can also be thought of as steering wheel effort; the more assist from the motor, the less effort from you on the steering wheel and vice versa. Steering wheel effort depends on the current steering wheel angle and vehicle speed. Note that for the best responsiveness and sensitivity from the road, tires, etc., power steering should feel exactly like manual steering, but with less effort. Let’s look at slow vehicle speeds first. At speeds from 0 to 10 kph, you are assumed to be driving in a parking lot. As such, steering wheel effort should be greatly reduced and constant, regardless of speed and steering wheel angle. This gives easy, smooth turning while driving around parking lots and parking the vehicle. Requirement #4: Steering wheel effort should be a constant (blank) for all steering wheel angles and vehicle speeds under 10 kph. Again, this value has been left blank because in vehicle testing is needed determine the appropriate amount of effort for comfortableness. At speeds above 10 kph, we have the following requirements: Requirement #5: Steering wheel effort increases with increasing steering wheel rate. (Damping) Requirement #6: Steering wheel effort increases with increasing steering wheel position. (Springing)

Requirement #7: Steering wheel effort increases with increasing lateral acceleration. Requirement #8: Steering wheel effort increases in magnitude with increasing vehicle speed. These requirements have not been given values yet because in vehicle testing is required to determine the appropriate magnitudes. However from a qualitative view, the reasons are as follows. As steering wheel rate increases, i.e. you turn the wheel faster, steering wheel effort should increase to dampen your steering wheel rate. This will provide feedback to the driver when making sharp turns which will help prevent overturning the wheel and unsafely changing the direction of the car. Steering wheel springing has a similar affect, and also helps the driver be aware of how far the steering wheel is turned, to avoid things like running into the rack lock with too much force. Increasing steering wheel effort with increasing lateral acceleration is another way to give feedback to the driver; for example if you begin to oversteer, the lateral acceleration will increase, therefore increasing the steering wheel effort giving you a sense that it is happening. All of these characteristics should increase in magnitude as vehicle speed increases, because vehicle wheel angle has a bigger impact on vehicle direction as vehicle speed increases. The next characteristic of steering wheel effort we’ll look at is the transient response of the torque assist from the power steering motor. Ideally, there will be no sign of hysteresis or torque deadband during transient turning from the motor. However, during a change from a steady position of the steering wheel to a different position of the steering wheel, there will be an inherent delay of torque assist from the motor because of electrical delay, computation time, etc. There will also be a limitation of how quickly the motor can change assist from one direction to another, as in turning right, then quickly turning left. Requirement #9: Delay of torque assist from the power steering motor should be less than (blank) during a steering wheel position change from steady position to +/- 90 degrees. Requirement #10: Torque assist should not deviate more than (blank) from the theoretical torque assist curve during a steering direction change. Values have been left blank because in vehicle testing is needed to determine the point at which the driver can sense the torque assist delays. Another important characteristic is the steering gear’s response to road input. Ideally, the steering won’t respond to small forces, also called “white noise.” This feature is a low pass frequency filter. Larger bumps in the road can be felt for the sake of driver response, but don’t affect overall steering line; this is known as a low pass amplitude filter. Requirement #11: Steering doesn’t respond to white noise at frequencies below (blank). Requirement #12: Road input above (blank) amplitude can be felt by the driver, but don’t affect overall driving line.

In vehicle testing is necessary to determine the values at which the driver is most undisturbed by road input, but still has a good connection with the road. Lastly, the return rate of the steering wheel to center when the driver lets go needs to be characterized. Requirement #13: Return rate increases with increasing steering wheel position. Requirement #14: Magnitude of return rate increases with increasing vehicle speed. With these requirements, the steering wheel will quickly return towards center if let go from a large angle, and slowly decrease in rate as the wheel approaches center, for a smooth transition back to center. In addition, at higher vehicle speeds, the rates of return will increase because steering wheel angle has a larger effect on vehicle direction at higher speeds. Testing without the Tune: So, we have laid out the first draft of our GEN III requirements. You may have noticed that many of the requirements need “in vehicle testing” and that some are arbitrary and based on the driver’s preference. This is inevitable, and requires collaboration of individuals considered “experts” on correct steering feel. Not only are some of the metrics arbitrary, they may also be independent of the individual steering gears. Just like we are going through, each steering gear manufacturer has done testing and validation to develop a “tune” for their steering gear. Because some requirements are arbitrary, things like steering wheel return rates, steering wheel damping, etc. can be different from gear to gear solely based on different tunes; not because of mechanical differences in the gears. So what aspects can be tested that are independent of a given steering gear’s tune? Steering wheel angle to rack position correlation System power, i.e. tunability potential Torque assist delay Transient response of torque assist As we saw before, steering wheel angle to rack position can be somewhat tuned through the properties of the coupler piece, but the rest is influenced by mechanical compliance in the system. System power is related to the equation P=Tω, that is, power is equal to torque times angular velocity.

Previously, a “catch-up test” was performed with various vehicles. In this test, at 0 kph, the steering wheel is turned from 0 to 360 degrees, at increasing steering wheel rates. The maximum required input torque at the steering wheel is plotted against the steering wheel rate above. What we notice is that for each car, after a certain steering wheel rate the input torque required dramatically increases. It is at this point that the maximum system power has been reached. The higher the maximum power is for a gear, the more potential for tuning it has because of the relationship between the angular velocity and torque supplied. Every steering gear will try to deliver torque assist as quickly as possible, regardless of the tune. Therefore, the torque assist delay and its transient response when changing steering directions can be evaluated from gear to gear. Thus, these are the four characteristics we need to focus on assessing with each steering gear. Ergo, we will be testing on a capacity and potential basis. We don’t need to test each gear on whether it can perform all of our requirements; we need to test for which can meet all the requirements at the lowest price. Motivation for a Test Bench: As previously stated, the gears need to be evaluated on an A to B to C comparison, meaning all factors should be equivalent from test to test, and the tests should be run in an identical manner with a repeatable and reproducible procedure. Attempting to test multiple steering gears in-vehicle presents some problems. To keep all factors the same, we would need to use the same vehicle, so that suspension dynamics, tires, etc. remains the same from test to test. Also, the upper and lower U-joint angles need to be identical for each gear, to maintain equivalent U-joint velocities which impact steering characteristics. However, each steering gear has a different angle between the rack centerline and the pinion, which means the shaft angles would be different for each gear to keep the column in the same place. As you can see, packaging

becomes prohibitively difficult. So, if we test the gears on a bench, we have the benefits of freedom of configuration and elimination of any compliance beyond the steering rack. This way, we can focus on the behavior of the gears independent of their tune, and the other components of the car. Bench Testing: The following tests have been developed to specifically test each steering gear against the four characteristics we laid out earlier.

1. Constant steering wheel rate a. Parameters

i. Travel: lock to lock ii. Rate: slow, medium, and fast1 constant rates

iii. Load: high2 rack load b. Desired results

i. Coherence: rack moves with perfect correlation to steering wheel angle throughout the tests

ii. Effort: torque deadband is zero3

2. Increasing steering wheel rate a. Parameters

i. Travel: lock to lock ii. Rate: slow to fast

iii. Load: high rack load b. Desired results

i. Coherence: rack moves with perfect correlation to steering wheel angle throughout the tests

ii. Effort: torque deadband is zero

3. Impulse movements a. Parameters

i. Travel: 0 to 90 degrees; 150 to 60 degrees ii. Rate: medium and fast

iii. Load: high rack load b. Desired results

i. Coherence: rack moves with perfect correlation to steering wheel angle throughout the tests

ii. Effort: torque deadband is zero

4. Slalom/Frequency sweep a. Parameters

i. Travel: -40 to 40 degrees back and forth ii. Rate: slow, medium, and fast; slow to fast to slow

1 “Fast” rate = fastest possible human rate (400 deg/sec) 2 “High” rack load = rack load at 40 mph in slalom (15 kN) 3 Indicates no delay of torque assist from motor

iii. Load: high rack load b. Desired results

i. Coherence: rack moves with perfect correlation to steering wheel angle throughout the tests

ii. Effort: torque deadband is zero iii. Transition: torque assist transfer is immediate upon transition of direction

5. Catch-up test

a. Parameters i. Travel: 0 to 360 degrees

ii. Rate: slow, medium, and fast iii. Load: high rack load

b. Desired results i. Coherence: rack moves with perfect correlation to steering wheel angle

throughout the tests ii. Effort: torque deadband is zero

iii. System power: knee point is far to the right and low on torque-velocity curve

Bench Test Fixture Design The test fixture has been designed to specifically satisfy the needs of our tests, and to maintain an A to B to C type comparison between the tests. The steering racks are rigidly mounted and a hydraulic cylinder loads the racks from one side, on center with the centerline of each rack. This minimizes the complexity of the hydraulic control logic by allowing a constant force to be applied to each rack throughout the tests. This force applied is to simulate “road load,” the loads seen by the steering racks produced by lateral acceleration, tire scrubbing, bump steer, etc.

The above picture shows a side view of all four racks concentric on their rack centerlines (marked by the small white x) 200 mm above the table. By first constraining the racks to a common line, the hydraulic cylinder can be mounted concentric with the same line, ensuring

Racks’ centerline

the load is directed head on into the racks, without changing as the rack moves left to right. Below is an overhead view.

The tan prism and cylinder is the hydraulic cylinder, load cell, and rod end assembly, and the green angle pieces are the mounting for the cylinder. Most of the hydraulic cylinder related components and operations are being overseen by Steffen Leopoldsberger’s group in the Body and Chassis Lab (mainly Joshua Liu and Chris Kelley). As mentioned before, an important requirement of each test is that both U-joint angles are equivalent from test to test. Therefore, in CATIA V5, a shaft and column assembly was added to each steering rack assembly with equivalent U-joint angles to the current Model S set up. (Note: the distance from rack center line to the center of the lower U-joint is also equivalent for each steering gear assembly so that the compliances of the connecting shafts are equivalent). With the racks constrained on a line, the next step was to determine the rotational position about the line and the left-to-right position of each steering gear assembly. After spending some time in CAD, the following was achievable: while allowing each assembly to move freely left to right and rotate about the centerline, but maintain equivalent upper and lower U-joint angles, the column position of each assembly can reside parallel to the table top at a height of 434 mm, and reside with the front to rear centerline of the column parallel to the side of the table (which makes it perpendicular to the rack centerline, see previous two images). This means that from test to test, the column can be mounted such that it only needs to move freely front to back. The solution for this is a Bosch Rexroth extruded aluminum fixture, as can be seen in the image below. (Note: this mounting configuration should suffice for any steering gear with a pinion to rack centerline angle of 60 to 90 degrees).

The column, shown in purple, mounts to an aluminum pad that can be adjusted forward and backward. At this point, each steering gear assembly is constrained in space and the racks can be mounted to the table. Since the mounting positions are different for each rack, and because they are arbitrarily rotated about the centerline, unique rack mounts have been made for each steering gear. They have also been designed to have similar compliances (maximum deflection under load of 0.01 to 0.05 mm) to maintain the A to B to C type comparison between tests. The JLR gear’s rack mounts can be seen in the image below. Also notice the clevis piece (rust colored) that threads onto the inner tie rod of the steering rack and connects to the rod end on the hydraulic cylinder piston.

To continue to be consistent with the A to B to C type comparison testing, the steering input needs to be repeatable and reproducible. The best way to do this is with a steering robot, which we have been lent from the Vehicle Test group. The robot is a model SR-60 from Anthony Best Dynamics (ABD), and is controlled by their proprietary software, which has been loaded onto the data acquisition workstation next to the test fixture in the Body and Chassis Lab. The robot mounts directly onto the column, and is reacted by two adjustable shafts with rod ends on both ends that bolt to the table (see next image).

As you can see, the design of the fixture allows A to B to C evaluation of each gear by maintaining equivalent U-joint angles, component compliance (exterior the steering gear itself), hydraulic loading, and steering input across all testing for each gear.

BOM (Generic components)

Item Description Qty

Test table 1

Model S Upper I-Shaft 1

Model S Column 1

Column mounting structure 1

Column mount pad 1

Column mount pad to slider bolts M8 x 1.25 4

Column mounting structure to table bolts M8 x 1.25 8

Hydraulic cylinder 1

Hydraulic cylinder rear mount 1

Hydraulic cylinder front mount 1

Load cell 1

Load cell rod end 1” rod end 1

Load cell rod end to mock outer tie rod joint bolt 1” – 14 bolt 1

Load cell rod end to mock outer tie rod joint nut 1” – 14 nut

Steering robot 1

Steering robot reaction bar ½” steel solid bar, 360 mm long 2

Steering robot reaction bar rod end (RH) 5 mm (RH) rod ends 2

Steering robot reaction bar rod end (LH) 5 mm (LH) rod ends 2

Steering robot reaction bar table mounts 2

Steering robot reaction bar table mounts to table bolts

M8 x 1.25 2

Rack mounts to table bolts M10 x 1.25 8-12

Power supply CUI Inc VSCP-2K4-12, 12V, 200 Amp

1

Positive/ground wires from power supply to steering gear

6 gauge, Anderson quick connect connecter

1

Current transducer LEM HASS 50-S 1

Positive, ground, and signal wires from current transducer to DAQ workstation

22 gauge, twisted 1

Various Steering robot wires

CAN dongle Vector CANcase XL 1

CAN wires from steering gear to CAN dongle 22 gauge, twisted, quick connect connectors

1

BOM (Unique components) ZF Ball Screw

Item Description Qty

ZF Ball Screw type steering gear 1

ZF Ball Screw rack mounts (L/R) 2

ZF Ball Screw mock outer tie rod Tapped for M18 x 1.5 thread of inner tie rod

1

ZF Ball Screw rack mounts to steering gear bolts M14 x 2 2

ZF Ball Screw lower I-shaft 1

ZF Ball Screw positive/ground wires 6-10 gauge, Anderson quick connect connector

1

ZF Ball Screw CAN High, CAN Low, and IGN wires

22 gauge, twisted, quick connect connector

1

NSK

Item Description Qty

NSK blank type steering gear 1

NSK rack mounts (L/R/middle) 3

NSK mock outer tie rod Tapped for M14 x 1.5 1

NSK mount spacer (L/R/middle) 1

NSK rack mounts to steering gear bolts M14 x 2 3

NSK lower I-shaft 1

NSK positive/ground wires 6-10 gauge, Anderson quick connect connector

1

NSK CAN High and CAN Low wires 22 gauge, twisted, quick connect connector

1

Mando

Item Description Qty

Mando blank type steering gear 1

Mando rack mounts (L/R) 2

Mando mock outer tie rod 1

Mando right mount spacer 1

Mando rack mounts to steering gear bolt M14 x 2 2

Mando lower I-shaft 1

Mando positive/ground wires 6-10 gauge, Anderson quick connect connector

1

Mando CAN High, CAN Low, and IGN wires 22 gauge, twisted, quick connect connector

1

Daimler

Item Description Qty

Daimler blank type steering gear 1

Daimler rack mounts (L/R) 2

Daimler mock outer tie rod 1

Daimler rack mounts to steering gear bolts M12 x 1.75

Daimler lower I-shaft 1

Daimler positive/ground wires (same as ZF Ball Screw)

6-10 gauge, Anderson quick connect connector

1

Daimler CAN High, CAN Low, and IGN wires (same as ZF Ball Screw)

22 gauge, twisted, quick connect connector

1

Data Acquisition Data acquisition will take place through LABview on a workstation set up adjacent to the test bench. The following data will be logged Piston/rack position Rack load Steering wheel angle Steering wheel torque

Power steering motor current The hydraulic cylinder piston displacement will be measured with a linear displacement potentiometer attached to the cylinder mounting and to the load cell. This will, in turn, measure rack position/displacement, and rack load will be measured by the load cell. Steering wheel angle and torque are measured by the steering robot and collected by the steering robot software, but can also be outputted via CAN or analog signal. Power steering motor current is measured by an LEM HASS 50-S current transducer. Rack position will be used in the hydraulic logic for position limited load control, as well as used for evaluating steering wheel angle to rack position coherence. Rack load will also be used for the load control. Steering wheel angle, as stated, will be used to evaluate coherence, and steering wheel torque will be used to evaluate driver effort requirements throughout testing. Testing Set Up Hook Up Make sure the following items are connected

Power supply to wall Power supply to steering gear CAN wires from steering gear to dongle Current transducer wires to DAQ workstation Steering robot controller to DAQ workstation Steering robot controller to dongle Linear pot to DAQ workstation Load cell to DAQ station

The steering robot will output steering wheel angle and torque via analog signal to the DAQ workstation, and output steering wheel angle to the CANcase dongle via a DB9 CAN cable. CANape will take the steering wheel angle via CAN and feed it into the faux CAN network that is sent to the steering gear for proper operation. The DAQ workstation, through LABview, will record data from five channels: load cell load, linear pot position, steering wheel angle, steering wheel torque, and current to the power steering motor. LABview will also use the load cell and linear pot channels for the hydraulic control logic. When everything is hooked up, open the proper LABview project to collect the five channels of data, and the steering robot software. Set up or run the desired steering input, while recording data, and then evaluate the data. Refer to the steering robot software manual installed on the DAQ workstation for more information on the software (located under ABD Robot Controller – Documentation – RC7 Software manual). Incomplete Items Mando and Daimler Lower I-shafts

The lower I-shafts for the Mando and Daimler steering gears still need to be ordered from Walter at GSS (Global Steering Systems). The dimensions of these should be exactly the same as the NSK lower I-shaft that has just been received from GSS, except for the following dimensions: Cinch bolt center to U-joint center (Mando): 249 mm Pinion centerline to cinch bolt center (Mando): 14 mm Cinch bolt: M8 Cinch bolt center to U-joint center (Daimler): 227 mm Pinion centerline to cinch bolt center (Daimler): 14 mm Cinch bolt: M8 In addition, the spline profile information for each remaining gear needs to be acquired from the respective companies, and sent to GSS with these dimensions. Mando Wiring Harness Mating connectors and crimp terminals have been sent to us by NSK for both the power connection and the CAN signal connection. Next, using the wiring and connectors that have been used on the other harnesses, the Mando harnesses for power and CAN signal need to be created. Take note to properly match the positive and ground wires to the existing Anderson quick connect connector currently attached to the power supply, and to match the CAN High/CAN Low/Ground/IGN pins on the existing wires currently attached to the CAN dongle. Daimler Steering Rack A Daimler steering rack needs to be acquired for use in testing from Robin Shute, which should be available by the end of January. CANope CAN Network The CAN network needs to be set up for all of the gears in order to turn on and communicate with the gears properly. This is currently being worked on by Zeljko Popovic. Program Steering Robot Tests A couple of the tests have been already programmed into the steering robot software, but may require some tweaking depending on your preference of how the tests are run. The remainder of the tests will need to be programmed, obviously, in order to be run. Refer to the steering robot software manual installed on the DAQ workstation for help with this. Hydraulic Controls Set Up Chris Kelley and Joshua Liu are currently working on setting up the hydraulic cylinder for force control. Contact them for a status update and what is needed to be done next.

Order History Digi-Key Order # 37977612 Items: LEM HASS 50-S current transducer, wiring accessories Cost: $68.26 Digi-Key Order # 37855133 Items: CUI Inc VSCP-2K4-12, 12V, 200 Amp Power Suppy Cost: $1740.34 Remy Battery Order # 11950 Items: 4 Gauge 175 Amp Anderson quick connect connector Cost: $123.03 McMaster-Carr Invoice # 65334898 Items: Various wiring Cost: $280.11 McMaster-Carr Invoice # 6553800 Items: Various steel for rack mounts Cost: $946.51 McMaster-Carr Invoice # 2968063 Items: Various steel/aluminum for clevis pieces Cost: $127.30 McMaster-Carr Invoice # 3011802 Items: Rod ends and hardware Cost: $94.18 ASW R&D Machining Inc. PO # 4700035912 Items: Aluminum Shims Cost: $50.00 ASW R&D Machining Inc. PO # 4700035813 Items: Clevis pieces, steel bushings Cost: $775.00

ASW R&D Machining Inc. PO # 4700035165 Items: Clevis pieces, steel bushings Cost: $473.00 ASW R&D Machining Inc. PO # 4700034615 Items: Clevis pieces, table mounts Cost: $550.00 Valin Corp Order # 2113852 Items: T-blocks Cost: $25.89 Valin Corp Order # 2111837 Items: Corner plates and hardware Cost: $363.04 Valin Corp Order # 2099340 Items: Gussets Cost: $60.91 Valin Corp Order # 2099340 Items: Column mounting structure Cost: $271.82 Global Steering Systems Order # Items: NSK Lower I-shaft Cost: $400.00 Total: $6349.39 Budget: $20,000.00 Surplus: $13,650.61