Electric Vehicle

Electric Vehicle is a build event. Your team designs and builds one battery-powered vehicle before the tournament, and on competition day it has to do three things in a single autonomous run: drive forward and catch a plastic Water Bottle sitting on the track, push that bottle past a taped Bottle Line beyond the Target Point, and then back up so that its rear Measurement Point stops as close as possible to the Target Point, all in a run time close to an announced Target Time. The bottle task is new for 2027 and it changes the event: the score now has a vehicle-distance term, a bottle-distance term, a time term, a bonus for clearing the Bottle Line and a bonus for a narrow pusher, and the vehicle must be able to drive in both directions.

Teams that score well treat the event as a repeatability problem. You are not rewarded for speed or for a light car. You are rewarded for a vehicle whose stopping positions (bottle and rear point) you can predict to within a couple of centimeters, so that one of your two runs lands almost exactly where you planned. That takes engineering (a chassis that tracks straight, a reversible drivetrain with little play, a pusher that holds the bottle without tipping it) and measurement (a logged calibration across every target the rules allow).

Electric Vehicle is a Division C event.

Event format

There is no written test. What there is instead is a design-knowledge requirement (Section 3.j): you must be able to answer questions about the design, construction and operation of your vehicle under the Science Olympiad Building Policy on soinc.org.

What the rules cover

The 2027 rules manual pages for this event are short, but the ES checks nearly every line. Section numbers below refer to the 2027 Division C manual.

The numbers that change by level

The Target Distance, Target Time and Bottle Line Distance are announced and posted after impound and before the first time slot, and they are the same for every team at that tournament. A calibration that is fine at a Regional can be far too coarse for a National, where both distances can land on any centimeter.

What changed from last season

If you competed in 2026, unlearn these: the Target Distance range moved down to 5.00 to 9.00 m; the can bonus and Bonus Line are gone and the Water Bottle task replaces them; the Time Score is now weighted at 0.5 points per second; the length limit now covers the whole vehicle (80.0 cm) instead of wheel-to-wheel; the Measurement Point moved from the front to the rear and must be the rearmost part; purchased and open-source kits are now allowed with conditions; there is a new rule on who writes the program; and the tiebreakers changed.

The 2027 task, step by step

Picture the track from above. The Start Point and Target Point are small pieces of tape (about 5 cm by 2.5 cm) with a dot at the center of each. An imaginary center line runs from the Start dot through the Target dot; it is not drawn on the floor. The Water Bottle stands on that line at 2.0, 3.0 or 4.0 m from the Start Point depending on the level, and it is not optional: it is always there. Beyond the Target Point, at the Bottle Line Distance, a strip of tape about 2.5 cm wide crosses the center line at right angles; this is the Bottle Line, at least 1.0 m long and centered on the line, and the edge nearer the Target Point is the line that counts.

A run then goes like this.

1. You set the vehicle with its rear Measurement Point over the Start Point (within about 1 cm), and its body on the Target side of the Start Point. The Vehicle Front is defined as the side facing the Target Point, so the pusher faces down the track.
2. You trigger it with an unsharpened #2 pencil, moving vertically.
3. The vehicle drives forward, reaches the bottle and captures it in the Bottle Pusher at the front.
4. It pushes the bottle past the Target Point and on until the bottle is fully past the Bottle Line.
5. It stops, leaves the bottle behind, and reverses until its rear Measurement Point is as close as possible to the Target Point.
6. It comes to a complete stop (still for at least 3 s), which ends the Run Time.

The track is a smooth, level, hard surface. The track area is 2.0 m wide and extends at least 1.0 m past the Target Point (more room may exist but is not promised, even though the Bottle Line can be up to 3.00 m past it). If the ES sets up more than one track, you choose one and must use it for both runs.

The ES then measures the Vehicle Distance (point to point, MP to Target Point, to 0.1 cm) and the Water Bottle Distance (point to line, from the Bottle Line to the bottle's nearest side, to 0.1 cm, using a square), and checks that the bottle was moved legally.

Scoring: the formulas that decide the event

Read every term as a cost. Lower is better.

The exchange rates

Put every term on one scale before you decide where to spend effort:

Three lessons fall out of this table. First, the rear-point stop is still the most valuable precision in the event. Second, time matters much less than in 2026: being a full second off costs what a 2.5 mm stopping error costs. Third, losing the bottle is a catastrophe compared with everything else, so the pusher and the capture must be reliable before they are aggressive.

Worked example: a strong run

Change only the bottle: if it stops 3.5 cm short of the line, the bottle term is still 3.50 but the bonus is lost, so the run scores 73.21. If the bottle tips over, the bottle term becomes 400.0 and the run scores about 469.71 (with the pusher bonus still counted, see the note below). The same vehicle stop is worth very different scores depending on what the bottle did.

Aim the bottle past the line, not at it

The bottle cost is lopsided. If the bottle stops short of the line, or straddles it, you pay its distance to the line with no bonus (when it straddles, the ES measures both its front and back sides to the line and uses the smaller). If it is fully past, you still pay its distance, but you also get −20. So:

Overshooting by anything up to 20 cm still beats every short result. If your bottle position scatters by ±4 cm run to run, aim for the nearest side to land about 5 cm past the line, so even a bad run is fully beyond.

The pusher trade-off

A narrow pusher earns a large bonus: 1.5 points per centimeter, so going from a 20 cm funnel to a 10 cm cup saves 15 points. But the bottle is 6 to 7 cm across, and a narrow mouth gives little room for a sideways miss at capture. Think of it as expected value. If narrowing the mouth by 5 cm (worth 7.5 points) raises your chance of losing the bottle by even 2%, it costs about $0.02 \times 420 = 8.4$ points on average and is not worth it. Narrow the pusher only after testing shows the capture is reliable at that width.

Penalties, failed runs and ties

Run penalties are flat amounts per run: Competition Violation +150 (one or more), Construction Violation +300 (one or more), and the Non-modification Penalty +50 for breaking the kit rules. A Failed Run can still collect violations. The only Final Score penalty is +5000 for a vehicle that was not impounded. Impounding more than one vehicle puts a construction violation on every run.

A run is a Failed Run if the vehicle moves the wrong way from the Start Point, starts before the ES is ready, cannot be measured (for example you pick it up first), or is pushed by the team. If you get only one successful run in the 8 minutes, the second is scored as failed; if the vehicle never moves, both are. New for 2027, a team may ask for a run to be scored as failed, and if that is the second run, Event Time stops right there.

Ties: two or more teams with two Failed Runs and no violations stay tied. Otherwise the order is (1) the better Distance Score of the scored run, which now includes the bottle term, (2) the lower Time Score of the scored run, (3) the better Vehicle Distance of the scored run, and (4) the smaller Bottle Pusher measurement.

Construction rules

These come from Sections 3 and 8. Make a checklist of them and run it before every impound and every run.

Energy and batteries

All electrical energy the vehicle uses for any purpose, motors and electronics alike, must come from at most eight AA batteries. Each must be a commercial AA (rechargeables allowed), between 1.2 and 1.5 V fully charged, carry its original manufacturer's label where the ES can read it, and be an individual cell you can take out of any pack. Batteries containing lithium or lead are banned outright, and a team using them may not run and gets participation points only. Note that this rules out lithium AA primary cells, not just lithium-ion packs, and it also rules out a coin cell on a microcontroller board or a USB power bank feeding the electronics.

You may not use storage that lets the vehicle exceed the instantaneous energy the batteries can deliver; the rules give large capacitors and springs as examples. Small filter capacitors on a circuit board are normal electronics, but if you are unsure about a part, ask the ES in advance and keep the answer in writing. Devices used only for sighting, aligning or aiming may run on a separate power source, but lasers are banned everywhere. All energy sources must be easy for the ES to inspect, and the batteries are impounded separately from the vehicle.

Components and electronics

Parts may be bought or made. Electronic components (transistors, ICs, diodes, microprocessors) are allowed, and you may talk to a microprocessor over Wi-Fi, Bluetooth or USB. Two sensing restrictions matter for design: cameras of any type are prohibited, and so are sensors that contain lasers. Many small time-of-flight distance sensors use a laser emitter, as do laser mouse sensors, so check the datasheet for any optical sensor before you build around it. Wheel encoders (magnetic or LED-based optical) and inertial sensors such as gyroscopes contain neither, and are the usual way to sense distance and heading.

Size and shape

The Bottle Pusher

The pusher is the new device rule (Section 3.f) and it is strict. In your own words, the checklist is:

• It is mounted at the front and is the frontmost part of the vehicle.
• Only one pusher may be impounded, so do not impound a spare.
• It is rigid: no flexing, no moving parts, no change in size, and it cannot be relocated on the vehicle.
• Its foremost edges are rounded to roughly pencil thickness or more (a #2 pencil is about 7 mm across).
• It must work with bottles that are not perfectly round.
• The bottle does not have to fit entirely inside it.
• If you started from a kit, the pusher cannot come from the kit; you design and build it.

At check-in the ES measures the widest opening of the pusher's mouth to 0.1 cm, and that number sets both your Pusher Bonus and the zone where the bottle is allowed to touch.

The Measurement Point

The Measurement Point (MP) is now at the rear and must be the rearmost part of the vehicle. It can be made of anything (a skewer or toothpick tip, a pencil or pen tip, a nail or wire tip, the corner of a wedge, the edge of a dowel), must be no more than 1.0 cm above the track, and must be easy for the ES to measure from. Make it stiff: a bent MP changes your Vehicle Distance without changing the car, and because it is the rearmost part it is what you are reversing toward the Target Point.

Control, floor contact and parts

No remote control and no tether: the run is autonomous. Everything moves as one piece, so no anchors, tie-downs, launch ramps or separate pieces. During the run only the wheels or treads, plus anything already touching the floor in the ready-to-run position, may touch the floor. Anything that falls off during the run is a construction violation.

Kits and the program

Kits (purchased or open-source) are allowed in 2027 if you meet three conditions: you make at least two functional modifications during the build and record them on the Kit Modification Form from soinc.org (which is impounded); you build your own Bottle Pusher; and the kit supplies only common parts you could get elsewhere, so no custom printed circuit boards. The rules also mention 3D-printed plastic parts in this condition; the sentence is most often read as exempting them, but the wording is brief, so confirm with the ES or an official clarification before relying on kit-supplied printed parts. Breaking any of these adds the 50-point Non-modification Penalty to each run.

The program must be written by at least one member of your school's 15-member team. Starting from a skeleton or blank-shell program (from the internet or from a same-school competitor) is fine, and so is borrowing small code sections or examples, but a program taken whole from a single source is not. Breaking this is a construction violation. In practice: write it yourselves, keep comments and a version history, and be ready to explain any line.

The competition procedure

Impound happens before the first time slot; any member of the 15-member team may impound, and nothing is inspected then. After impound, the three targets are posted.

At check-in, only participants enter, with their tools. The ES tells you when to collect your impounded items, then inspects and measures the vehicle, including the pusher opening, and tells you about any construction violations. You may spend Event Time fixing them, and the clock is paused while the ES re-checks. From the start of check-in you may not leave or receive outside help or materials until your Event Time is over.

During Event Time (8 minutes, ending after two runs):

• Sighting, aligning, measuring and guiding devices stay inside the track area and cannot be fixed to the floor. Teams from the same school may share an alignment device. Anything not on the vehicle must be moved behind the Start Point before a run. No lasers.
• You may verify track dimensions with your own tools. You may not put tape on the event floor. Substances on the vehicle need ES approval and must leave no residue; you may clean the track, but it must stay dry.
• A vehicle that is in the ready-to-run configuration before the 8 minutes run out may still complete that run.
• No rolling or testing on the track floor on the event day or the day before without tournament permission, and no rolling on the floor before or after runs.

For each run: place the MP over the Start Point (within about 1 cm) with the body on the Target side; the vehicle must sit still untouched until triggered; tell the ES you are ready, which pauses the clock while the ES reviews the ready-to-run vehicle. The ES reports competition violations only at the end of the run and answers specific questions, not "do we have a violation?". Start with a vertical pencil motion; only the pencil may touch the vehicle. If it does not move, no run has happened and you can keep working. From the start until you retrieve the vehicle, programming tools stay closed. Do not follow the vehicle down the track before you are called (competition violation). The ES records Run Time, Vehicle Distance and Bottle Distance and checks the bottle rules; the clock restarts when you pick up the vehicle or start working again. At the end the ES reviews the recorded data with you, and teams that appeal must leave the vehicle and impounded materials in the event area.

The Water Bottle and the Moving Water Bottle Requirements

The bottle is a single-use, clear plastic 16.9 oz (500 mL) water bottle, 6 to 7 cm in diameter and 18 to 22 cm tall, with a mass of 80 to 100 g. It holds no liquid; non-lead metal BBs or similar may be added to bring it up to mass. Different tournaments may use different brands, so the shape (ridged, square-shouldered, smooth) can vary.

For the bottle term to count, the move must follow four requirements (Section 8.l), here paraphrased:

1. The bottle touches the floor at all times, and no part of the vehicle gets underneath it.
2. It stays upright.
3. It is only ever pushed, never pulled, lifted or carried.
4. Only the pusher touches it, and only within the measured opening. A bottle that slides out of the mouth and brushes the vehicle body, a wheel, or the outside of the pusher arms has broken the rules.

Breaking any of these sets the Bottle Distance to 400.0 cm. The rules do not say whether the Bottle Bonus can still be earned after a violation; this guide assumes it cannot, so confirm with the ES.

The physics of a 2027 run

Run geometry: how far the vehicle actually travels

Let $D$ be the Target Distance, $B$ the Bottle Line Distance, $a$ how far past the line you want the bottle's near side to end, $s$ how far the bottle slides on its own after the vehicle stops pushing, and $L$ the distance along the vehicle from the pusher's contact surface back to the MP.

Over the full rule ranges, the total path runs from about 5.5 m (5.00 m target, 1.00 m line distance, a 75 cm car) to well over 14 m (9.00 m target, 3.00 m line distance, a short car). Combined with Target Times of 10.0 to 20.0 s, the required average speed spans roughly 0.3 to 1.4 m/s, and your drivetrain has to handle that range without hardware changes.

Run time and the start delay

Run Time starts when you actuate the vehicle and ends when it has been still for 3 s (those 3 s are not counted). Recoil and rocking count. Three timers are used and the middle reading is official. New for 2027, the rules state that any pause between actuation and the vehicle starting to move is part of the Run Time, and that this pause may be longer than 3 s.

That gives you a clean way to hit the Target Time: run a fixed, well-calibrated motion profile that takes less time than the target, and let a programmed start delay absorb the difference. For example, with a 12.0 s Target Time and a profile that takes 8.6 s, delay 3.4 s before moving.

Capturing the bottle

The bottle's position is fixed for your level (2.0, 3.0 or 4.0 m from the Start Point), so you know exactly where the collision happens. Treat it as a collision between a heavy vehicle (mass $M$) and a light bottle (mass $m$, under 0.1 kg). If the impact were perfectly elastic, the bottle would leave at up to

$$v_{\text{bottle}} = \frac{2M}{M + m}\, v \approx 2v$$

for a vehicle much heavier than the bottle. A bottle kicked ahead at twice the vehicle's speed slides away, slows by friction, and is hit again, and every bounce is a chance to knock it sideways or over. The fix is to slow down through the capture zone: plan a low-speed section a few centimeters either side of the bottle position so the contact is gentle and the bottle stays seated in the pusher.

Sideways tolerance at capture is set by heading error. A heading error $\theta$ gives a sideways offset of about $y = x \sin\theta$ after traveling $x$. At 4.0 m (Nationals), $0.5^\circ$ gives $400 \times \sin 0.5^\circ \approx 3.5$ cm. With a 9 cm mouth and a 6.5 cm bottle there is only about 1.25 cm of slack on each side, so a funnel or V that guides the bottle toward the center, or active heading control, is essential if you want a narrow opening.

Pushing without tipping

While you push the bottle at steady speed, the force you apply equals the friction on its base, $F = \mu m g$. That force acts at the height $h$ where the pusher touches the bottle and tries to rotate the bottle about its front base edge; the bottle's weight, acting at its center, resists with a lever arm equal to its radius $r$.

At steady speed the tipping height does not depend on the bottle's mass or center-of-mass height, only on the push height, base radius and friction. While accelerating, a lower center of mass (BBs in the base) lowers the tipping height slightly, so push gently. Heavier BBs do raise the friction force you must supply, and loose BBs can shift; test with bottles weighted to both ends of the 80 to 100 g range.

Releasing the bottle: how far it slides

When the vehicle brakes, the bottle keeps moving and slows only by friction at $\mu g$. If the vehicle stops faster than that, the bottle separates and slides:

At $v = 0.50$ m/s and $\mu = 0.4$: $s = 0.25 / 7.84 = 0.032$ m, about 3 cm. At 0.30 m/s it is about 1.1 cm. Because $s$ grows with $v^2$, a slow final push makes the bottle's resting place predictable. Measure $s$ on several floors and feed it into the run plan.

Distance per wheel turn and drivetrain play

Without slip, distance is wheel revolutions times circumference: $d = N \times 2\pi r$. A 3.0 cm radius wheel covers 18.85 cm per turn. Any error in the effective radius scales every leg by the same fraction. Because the forward and reverse legs partly cancel, the MP's final error is that fraction of the net displacement $D$: a 0.25% radius error with $D = 7.25$ m moves the MP by about 1.8 cm (3.6 points), and the bottle, which ends near $D + B$, by about 2.2 cm. Measure wheel diameter with calipers, keep treads clean, and calibrate on a surface like the competition floor.

Reversing adds a problem that one-way cars never had: backlash, the free play between gear teeth. When the motor reverses, it turns through the play before the wheels move. If your encoder is on the motor shaft, it counts that dead motion as distance. Mount encoders on the wheel or axle where possible, choose gears with low play, or measure the backlash and add it as a fixed correction to the reverse leg.

Choose $G$ so the motor runs in a comfortable part of its range across 0.3 to 1.4 m/s average speeds, with enough torque to push the bottle and to start cleanly in both directions. A higher ratio gives more torque and finer control at low speed, which suits the slow capture and the final creep to the Target Point.

Battery voltage and motor drive

Eight cells in series give 9.6 V (eight NiMH cells at 1.2 V) to 12.0 V (eight at 1.5 V). Under load the terminal voltage drops:

Reversing needs a motor driver that can run the motor both ways (an H-bridge), and electronics typically need a regulated 5 V or 3.3 V supply taken from the same AA pack. Closed-loop speed control hides most voltage sag; with open-loop control, use the same battery set, charged the same way, for calibration and competition.

Control and calibration

A segmented run profile

Most strong 2027 designs use a microcontroller, wheel encoders and often a gyroscope for heading, and break the run into segments:

Open-loop control (fixed motor times or powers) is simple but sensitive to voltage, floor and wheel changes. Closed-loop control (encoders counting wheel turns, a speed controller holding each segment's speed, a gyro holding heading) corrects for those changes, at the cost of more wiring, code and failure modes. Fix the mechanics first: a car that tracks straight and stops cleanly needs far less correction.

Calibration as an experiment

Calibrate the three outcomes separately, because they have different costs and different causes:

1. Forward distance and bottle position. Command several push-end positions, measure where the bottle's near side ends relative to a taped line, and fit a line through the data. Record the slide $s$.
2. Reverse leg. From a known forward stop, command several reverse distances and measure where the MP ends. Fit a separate line; forward and reverse calibrations usually differ because of backlash and weight transfer.
3. Motion time. Record the time from first motion to complete stop for each plan, so you can compute the start delay.

Report the mean error and the standard deviation for each setting. A small spread with a biased mean is a calibration fix. A large spread is a hardware problem (loose parts, slipping wheels, a pusher that lets the bottle wander) that no command can fix. Since Vehicle Distance is unsigned, aim the MP at the target itself; aim the bottle a few centimeters past the line because of the bonus.

Calibrating across the whole range

You cannot know the targets until after impound, so build a lookup table for every Target Distance and Bottle Line Distance at your level's step size (17 × 9 combinations at a Regional), plus the start delay for every Target Time. At State and National steps the table becomes a formula: check your linear fits at the low, middle and high ends of both ranges and use piecewise fits if the data bend. On the day, entering the announced numbers should be a lookup, not a calculation.

Designing the vehicle

• Chassis and alignment. A stiff frame keeps axles square; toe and camber errors become sideways error at the Target Point. Mount the motor so its torque does not twist the frame.
• Length budget. The 80.0 cm limit includes the pusher. A shorter $L$ means a longer reverse leg; a longer car tracks straighter. Pick $L$ consciously and measure it exactly, since it appears in your run plan.
• Pusher. A rigid, shallow, concave cup or V that centers the bottle, contacts it low, has rounded rims, and releases it cleanly on reverse. Prototype in cardboard to find the narrowest mouth that captures reliably with ridged and square-shouldered bottles, then build it in rigid material.
• Rear MP. Rigid, at or below 1.0 cm, rearmost, and visible to you while aligning, since you place it over the Start Point at the beginning and drive it to the Target Point at the end.
• Adjustability. Put the targets into the program through a quick input (buttons, a small menu over USB or Bluetooth) so changing them takes seconds of Event Time.
• Trigger. A switch a pencil can press from above without nudging the car.

Testing logs and practice

Log every run: date, surface, battery set and voltage, the D, B and Target Time, every command, the MP distance to 0.1 cm, the bottle distance and whether it was fully past, whether the bottle rules were met, the run time, and the computed Run Score. Change one variable per session. After each session compute the mean and standard deviation of the run score, not just the best run; a consistent car makes it much more likely that one of your two runs is excellent.

Test with several bottle brands weighted to 80 g and to 100 g, with the bottle at 2.0, 3.0 and 4.0 m, and with Bottle Line Distances from 1.00 to 3.00 m. Practice the full sequence (check-in, pusher measurement, entering targets, alignment, pencil start, retrieval) against an 8-minute clock.

Strategy during Event Time

If run 1 was clean, run 2 can try one small improvement. If run 1 failed or lost the bottle, run 2 should be the conservative plan. At Nationals, if run 1 is excellent, asking for run 2 to be scored as failed stops the clock and locks in an Event Time Bonus, though the bonus is small (every 30 s saved is worth 1 point).

Common pitfalls

How tournaments test this

There is no archive or question bank for this event, so there are no past-test statistics. The event is scored entirely on the vehicle and the two runs, plus the design-knowledge requirement.

In practice the ES checks four things. First, that the vehicle meets every construction rule (length, width, energy, pusher, MP, sensors, kit and program rules), which is decided at check-in. Second, how close the rear MP stops to the Target Point and where the bottle ends relative to the Bottle Line, both measured to 0.1 cm. Third, whether the bottle was moved legally. Fourth, whether you can explain your design and your code. The level changes the challenge: the bottle moves from 2.0 m to 4.0 m from the Start Point, and the step sizes for both distances shrink from 0.25 m to 0.01 m, so a National vehicle needs a continuous calibration rather than a short table.

Test yourself

There are no archived tournament questions for this event, so practice with the formulas. Work each problem, then check the solution. The numbers are invented; the scoring rules are those of the 2027 rules.

References and further reading

• Science Olympiad, 2027 Division C Rules Manual, Electric Vehicle, and the Kit Modification Form and Building Policy on soinc.org. Check every number here against the current rules and any official clarifications.
• SciOly Wiki, Electric Vehicle: https://scioly.org/wiki/index.php/Electric_Vehicle (linked for reference only; written for earlier seasons).
• OpenStax, College Physics 2e, chapters on kinematics, friction and momentum (collisions): https://openstax.org/details/books/college-physics-2e
• OpenStax, University Physics Volume 1, chapters on rotation and static equilibrium (the tipping condition): https://openstax.org/details/books/university-physics-volume-1
• The Circuit Lab guide on this site, for circuits, internal resistance and electrical measurement.