Proof That LLMs Solve Real-World Problems: The Two-State Tire Spike Design

A Real-World Test for AI: How an LLM Helped Refine My Snow Grip System Design

Hi everyone,

Call this a public service announcement post. Free for all.

I’m one of those cats who likes to build stuff—or at least spec out how to build it—and I’m currently working on a real-world design for a snow grip system for vehicle tires. This isn’t a made-up exam question; it’s a genuine engineering challenge I’m tackling.

I didn’t prime or tutor the LLM for this problem—I just threw the question out of the blue. It got most things right, but its one mistake revealed an error in my own thinking. Seeing it reflected in the LLM’s response helped me correct it myself, refining and advancing the design in the process.

This is the kind of scenario I think the

Gary Marcus

’s of the world—and the ten thousand other critics who seem almost genetically incapable of acknowledging success—conveniently ignore. They love pointing out failures, but situations like this reveal the real value of the technology—and why you shouldn’t swallow the critics’ constant poo-poohing without question.

The Takeaway: Human Expertise is Key

Let me let you in on a secret. There’s something very important I’ve learned about working with these machines: you have to know what you’re talking about.

If you come in with expertise and a clear understanding of the problem, the LLM becomes an incredible tool. It can augment your thinking, provide new perspectives, and help refine ideas. But if you don’t know your subject, it’s like trying to steer a ship without a compass—it’ll wander, and so will you.

Below is the full exchange, unedited, for you to evaluate. Let me know what you think: does this example help improve the conversation about AI’s role in problem-solving?

[I] said:

Solve this puzzle. In a car tire there are embedded titanium tubes reaching down into the tread with a spike it in it that in retracted position is under the wear line of the tire and in extended position is over 1/2 " above the tread. It can lock on both ends. in retracted position it only unlocks when the tire is spinning, so that angular velocity is greater than it would be for the linear or vehicle velocity. In this case the spike will extend out but if it hits the contact patch (the road surface it will stay in a fere float state) until the tire rotates off the contact patch in which case it will full extend and lock. Once extended and locked it will stay that way unless the tire stops spinning, in which case if tiwll fully retract and return to lock at bottom state. Or, given a force threshold if the fully extended and locked spike hits dry pavement it will regfistore force of that thresheold and fully retract to lock in bottom state. Finally, in cases where you have a slide, tire angular = 0 (tire is not moving at all) and the linear velocity of the vehicle is non zero (the vehicle is sliding), it will extend spikes as described before and stay locked until angular begins off zero (vehicle is not sliding anymore). how does this tube with two "pop" or spring motions at the top and bottom and the other intervening stgates work?

ChatGPT said:

ChatGPT

The design you're describing for the tire spikes involves a clever mechanical and kinetic interplay between angular velocity, linear velocity, and force thresholds. Here’s how the system could work with the described functionality:

Components:

1. Titanium Tube Housing: A tube embedded within the tire tread holds the spike. It allows for two locking positions—retracted (bottom) and extended (top).

2. Spike: A robust spike capable of extending outward to penetrate surfaces when needed and retracting safely into the tube.

3. Spring Mechanism: A spring system at the top and bottom enables the spike to "pop" into position when certain conditions are met.

4. Force Sensor: Embedded at the tip of the spike to measure resistance when it makes contact with a surface (like asphalt or ice).

5. Angular and Linear Velocity Sensors: These sensors compare the tire's rotational (angular) velocity and the vehicle’s forward (linear) velocity to detect spinning or sliding.

6. Locking Mechanism: A mechanical lock at both the top and bottom positions ensures the spike stays securely in place when fully extended or retracted.

---

Working Mechanism:

1. Spike Extension During Tire Spin:

• The system detects tire spin by comparing angular velocity to linear velocity. If angular velocity exceeds the threshold for normal driving (indicative of spin), the bottom lock releases.

• A spring at the bottom pushes the spike upward into a "free-float" position. In this state, the spike is partially extended but cannot extend fully if obstructed by the road's contact patch.

• Once the road contact patch moves past the spike (as the tire rotates), the spring completes the extension, and the top lock engages to secure the spike in the fully extended position.

2. Spike Retraction After Spin Stops:

• When tire angular velocity aligns with linear velocity (indicating no more spin), the top lock disengages.

• A spring at the top retracts the spike fully into the tube, and the bottom lock secures it in the retracted position.

3. Force-Triggered Retraction:

• If the fully extended spike encounters a surface with resistance exceeding the force threshold (e.g., dry pavement), the force sensor triggers a mechanism to disengage the top lock.

• The spike retracts into the tube, and the bottom lock secures it in place.

4. Spike Extension During Slide:

• In a slide (angular velocity = 0, linear velocity > 0), the system detects the condition and releases the bottom lock.

• The spring pushes the spike upward into the free-float position, just like in the spin scenario. Once the tire rotates and moves past the road contact patch, the spike fully extends and locks at the top.

• The spikes remain extended until the slide ends (angular velocity becomes non-zero), at which point they retract as described earlier.

---

Mechanical Design:

1. Dual-Spring System:

   • Lower Spring: Compresses when the spike is in the retracted position, providing the energy needed for the spike to extend when the bottom lock disengages.

   • Upper Spring: Compresses when the spike is in the extended position, providing the energy for retraction when the top lock disengages.

2. Locking Mechanisms:

   • Bottom Lock: Engages when the spike is retracted and prevents unwanted extension.

   • Top Lock: Engages when the spike is fully extended and prevents unwanted retraction.

3. Sensors and Actuators:

   • Sensors detect spin, slide, and force thresholds, sending signals to small actuators that control the locking mechanisms.

4. Shock Absorber for Free-Float State:

   • A small damping system ensures that the spike’s movement during the free-float state is controlled to avoid damage to the road or tire.

This design achieves the desired functionality of automatically extending and retracting spikes under specific driving conditions, ensuring safety and optimal performance on various surfaces. The use of mechanical springs and locks ensures robustness, while sensors and actuators provide the intelligence for detecting conditions and triggering actions.

You said:

we need sensors to detect all states. explain each state and the sensor assigned to it.

ChatGPT said:

ChatGPT

To detect and respond to the various states of the system, sensors are crucial for capturing the required conditions. Here's a breakdown of each state, the necessary sensors, and how they interact with the spike mechanism:

---

1. Normal Driving (Default State)

• State Description:

  • No tire spin or slide.

  • Angular velocity aligns with linear velocity.

  • Spikes remain retracted and locked.

• Sensors Needed:

  • Angular Velocity Sensor (Gyroscopic Sensor): Measures the rotational speed of the tire.

  • Linear Velocity Sensor (Wheel Speed Sensor): Measures the vehicle's forward velocity.

  • Lock Position Sensor: Confirms the spike is fully retracted and bottom lock is engaged.

• Logic:

  • Angular velocity ≈ Linear velocity → No action; the spike stays retracted.

---

2. Tire Spin Detected

• State Description:

  • Angular velocity exceeds the expected value for the current linear velocity (indicative of spin).

  • Spikes extend to provide traction.

• Sensors Needed:

  • Angular Velocity Sensor: Detects increased rotational speed of the tire.

  • Linear Velocity Sensor: Detects unchanged or slower forward motion despite increased angular velocity.

  • Lock Position Sensor: Confirms that the bottom lock disengages and the spike transitions to the free-float state.

  • Contact Patch Sensor (Pressure Sensor): Confirms when the spike clears the road surface to fully extend.

• Logic:

  • Angular velocity > Linear velocity → Bottom lock disengages → Spike extends to free-float state → Spike locks when fully extended.

---

3. Force Threshold Exceeded (Dry Pavement)

• State Description:

  • Fully extended spikes encounter a surface with resistance exceeding the preset force threshold (e.g., dry pavement).

  • Spikes retract to prevent road damage.

• Sensors Needed:

  • Force Sensor (Load Cell): Measures the resistance force on the spike.

  • Lock Position Sensor: Confirms that the top lock disengages and the spike retracts to the bottom lock.

• Logic:

  • Force > Threshold → Top lock disengages → Spike retracts fully and locks at the bottom.

---

4. Tire Slide Detected

• State Description:

  • Angular velocity = 0 (tire is stationary).

  • Linear velocity > 0 (vehicle is sliding forward).

  • Spikes extend to provide lateral grip.

• Sensors Needed:

  • Angular Velocity Sensor: Confirms no tire rotation (angular velocity = 0).

  • Linear Velocity Sensor: Detects forward movement (linear velocity > 0).

  • Lock Position Sensor: Confirms bottom lock disengages and spike transitions to free-float state.

  • Contact Patch Sensor: Detects when the spike clears the road surface to lock in the extended position.

• Logic:

  • Angular velocity = 0 and Linear velocity > 0 → Bottom lock disengages → Spike extends to free-float state → Spike locks when fully extended.

---

5. Transition from Spin/Slide to Normal Driving

• State Description:

  • Angular velocity aligns with linear velocity (spin ends), or angular velocity increases from 0 (slide ends).

  • Spikes retract to the locked bottom position.

• Sensors Needed:

  • Angular Velocity Sensor: Confirms that angular velocity matches or exceeds linear velocity.

  • Linear Velocity Sensor: Confirms that vehicle is in normal driving conditions.

  • Lock Position Sensor: Confirms top lock disengages and bottom lock engages after retraction.

• Logic:

  • Angular velocity ≈ Linear velocity or Angular velocity > 0 → Top lock disengages → Spike retracts fully and locks at the bottom.

---

Sensor Summary Table:

StateSensorsPurposeNormal DrivingAngular Velocity Sensor, Linear Velocity Sensor, Lock SensorMonitor and maintain retracted state.Tire SpinAngular Velocity Sensor, Linear Velocity Sensor, Lock Sensor, Contact Patch SensorDetect spin, release bottom lock, extend spikes.Force Threshold ExceededForce Sensor, Lock SensorDetect excessive force, retract spikes to prevent road damage.Tire SlideAngular Velocity Sensor, Linear Velocity Sensor, Lock Sensor, Contact Patch SensorDetect slide, release bottom lock, extend spikes.Transition to NormalAngular Velocity Sensor, Linear Velocity Sensor, Lock SensorDetect return to normal driving, retract spikes.

This combination of sensors ensures the system can intelligently respond to all conditions while maintaining safety and efficiency. Each sensor plays a specific role in determining the current state and triggering the appropriate action for the spike mechanism.

You said:

there's a flaw in your logic. If you're in angular = 0 and linear > 0 then the spikes will pop from bottom and try to fully extend. the spikes under the contact patch will hit the road surface, and may go into free state. as the tire starts to rotate from ABS or pumping the breaks, the free float spikes now don't have a bottom connect spring to reextend. This suggest sthat the two states of the system can only be locked-retracted, locked-extended. do you agree?

ChatGPT said:

ChatGPT

Yes, I agree that the system should only have two distinct locked states—locked-retracted and locked-extended—for reliability and to avoid the failure scenario you've identified. Allowing a "free float" state introduces complications, especially when transitioning from a slide (angular = 0, linear > 0) to rotation (angular > 0) under braking or acceleration.

Here’s the reasoning behind limiting the system to these two states:

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1. Problem with the Free Float State

• Scenario:

  • During a slide, spikes attempt to extend while the tire is stationary.

  • Spikes under the contact patch encounter the road surface and cannot fully extend due to resistance.

  • If the tire begins to rotate (e.g., due to ABS or braking recovery), the spikes that were under the contact patch no longer have sufficient spring force or mechanical means to re-extend once the contact patch moves past them.

• Outcome:

  • Spikes may remain partially extended, causing an inconsistent system state that could lead to mechanical failures or reduced performance.

---

2. Proposed Solution: Two Locked States

To eliminate this failure mode, the system should only support these two states:

1. Locked-Retracted State:

   • Spikes are fully retracted and securely locked in position.

   • No intermediate or "free float" state exists.

   • Spikes only transition to the extended state when specific conditions (e.g., spin or slide) are met.

2. Locked-Extended State:

   • Spikes are fully extended and securely locked in position.

   • Once extended, spikes remain locked until specific conditions (e.g., normal driving or force threshold exceeded) are met to trigger retraction.

---

3. Behavior During Key Scenarios

A. During a Slide (Angular = 0, Linear > 0):

• Spikes remain locked in the retracted position until the system detects a slide condition (angular = 0, linear > 0).

• Once the slide condition is detected, the bottom lock disengages, and the spike extends completely before locking in the extended state.

• No intermediate state (free float) is allowed; spikes either extend fully or remain retracted.

B. When Tire Rotates from ABS or Braking Recovery:

• Spikes already in the extended and locked position are unaffected by the initial rotation.

• As the system transitions back to normal driving conditions (angular velocity > 0), the top lock disengages, and spikes fully retract before locking in the retracted position.

C. Force Threshold Exceeded (Dry Pavement):

• If the fully extended spikes encounter excessive resistance, the top lock disengages, allowing the spike to retract directly to the locked-retracted state.

• No intermediate state exists where the spike is partially extended.

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4. Advantages of Limiting to Two Locked States

• Reliability: Eliminating the free float state ensures the spikes are always in a known, stable position.

• Mechanical Simplicity: Reduces the number of required spring mechanisms and potential points of failure.

• Performance: Guarantees consistent behavior across all driving conditions (spin, slide, and normal driving).

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Updated Working Mechanism

• Extend Condition: Spikes transition directly from locked-retracted to locked-extended when triggered (e.g., during spin or slide).

• Retract Condition: Spikes transition directly from locked-extended to locked-retracted when triggered (e.g., normal driving or force threshold exceeded).

• No Intermediate State: Spikes never remain partially extended or in a free float state.

This revised design ensures that the spikes function consistently and safely across all scenarios.

You said:

I believe given the information we have this is correct now.