IMSystems

Protected: NOTION DATAROOM IQ

Casper van Eersel — Thu, 20 Nov 2025 10:40:28 +0000

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Protected: NOTION DATAROOM FININDUS

Casper van Eersel — Wed, 12 Nov 2025 14:12:37 +0000

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Protected: NOTION DATAROOM TEMPLATE

Casper van Eersel — Wed, 12 Nov 2025 14:02:35 +0000

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The Unique Archimedes Drive P.2

Casper van Eersel — Tue, 02 Sep 2025 00:00:42 +0000

Unique ARCHIMEDES DRIVE (part 2)

Summary

How Traction Changes the Game for Precision, Noise, and Speed

In the previous session, we introduced the groundbreaking Archimedes Drive—a hybrid mechanism that combines the compact power of compound drives with the smooth performance of traction rollers. Now, in this eighth class of the Archimedes Academy by IMSystems, we start comparing its unique properties to traditional gear systems.

This isn’t just a numbers game. With traction-based drives, performance isn’t always measured on the same scale as traditional gears. Some traits—like noise, backlash, and thermal limits—require a broader perspective. Let’s explore what makes the Archimedes Drive so special in three areas: precision, noise, and speed.

> Part 1: Torque Definitions: More Than Just a Single Number

Torque is a familiar term, but in practice, it’s split into multiple types—each relevant to different phases of a drive’s operation:

Understanding these distinctions is key when selecting a drive—and knowing what happens beyond those limits is even more critical.

> Part 2: Torque vs. Lifespan: The Trade-Off Curve

Drive lifespan is often specified using L10 life—the point at which 10% of drives are expected to fail. For industrial use, this is often set to 12 billion cycles. However, operating a drive at repeated peak torque can lower this to 100 million cycles or less.

Torque Multipliers:

Twice the rated torque → repeated peak load
4x the rated torque → momentary/emergency stop load

Each increase in torque typically means a tenfold reduction in lifespan. For example, the momentary peak torque in harmonic drives can cause premature fatigue in components like flexsplines.

> Part 3: What Happens When Drives Fail?

This is where traction technology shines. With traditional gear systems, over-torque can cause:

Catastrophic failure (broken steel parts)
Sudden system shutdowns

But with the Archimedes Drive, something very different happens:

It slips. And keeps working.

This feature is called over-torque protection. Instead of breaking, the drive slips momentarily—absorbing the shock—and then resumes function as if nothing happened.

Real-World Example:

IMSystems repeatedly smashed a test drive with a hammer (nine takes!)
The same demo unit had traveled the world for 1.5 years on the trade show circuit
After all that abuse? Still functioning perfectly

That’s the power of built-in mechanical resilience.

> Part 4: Controlled Degradation vs. Catastrophic Failure

Another major difference lies in end-of-life behavior:

Traditional Gear Drives	Archimedes Drive (Traction)
Metal fatigue → sudden failure	Performance slowly degrades
Machine halts without warning	Drive continues functioning
Requires urgent repair/replacement	Allows scheduled maintenance

In mission-critical environments—like automated factories or robotic warehouses—this difference translates directly to downtime savings and cost reduction.

> Part 5: The Weight Factor: Don’t Just Add Metal

Engineers might be tempted to extend life by beefing up the drive—increasing size, weight, and material strength. And while this can work, it compromises one of the most valuable advantages of the Archimedes Drive: torque density.

High torque density = more power in less space
Less weight = more efficient robots and machines
Lighter builds also mean lower energy consumption

The Archimedes Drive hits a sweet spot—delivering high torque without the weight penalty, and still maintaining excellent reliability under shock loads.

> Part 6: Summary: Torque Redefined

In traditional drives, more torque means more risk. In the Archimedes Drive, it means more adaptability:

Supports multiple torque ratings for diverse use cases
Slips instead of shattering—a mechanical fuse, not a failure point
Degrades predictably, enabling smart maintenance cycles
Achieves high torque without sacrificing weight or compactness

These are not just features—they’re fundamental rethinks of how mechanical power should behave under load.

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The Unique Archimedes Drive – P.1

Casper van Eersel — Tue, 26 Aug 2025 00:00:09 +0000

Unique ARCHIMEDES DRIVE (part 1)

Summary

How Traction Changes the Game for Precision, Noise, and Speed

> Part 1: Precision: Why the Archimedes Drive Is Exceptionally Accurat

When we talk about precision in drive systems, lost motion is the key metric—how much movement is “wasted” between input and output. Most of this is caused by backlash, especially in gear-based systems.

The Archimedes Drive eliminates this entirely:

No gear teeth = no backlash
Uses smooth rolling traction elements, ensuring immediate and accurate response
Higher stiffness than typical solutions, maintaining stable motion even under load

The result? Unmatched precision in any comparable class of drives. This isn’t just theoretical—visual comparisons show that gear drives produce wobble and audible clinks during movement. The Archimedes Drive, on the other hand, rolls quietly and smoothly.

> Part 2: Noise: A Key Factor in Emerging Applications

Noise might not be the first spec you look at in a drive system—but it matters. In sectors like prosthetics, wearable robotics, and collaborative robots (cobots), quiet operation is essential for user comfort and safety.

Understanding Decibels:

Decibel (dB) is a logarithmic scale
Every +3 dB = double the loudness
A +15 dB difference? That’s 32 times louder

Real-World Test:

In a prosthetics application, IMSystems compared two drives:

Drive Type	Max Noise Level	Equivalent Sound
Archimedes Drive	50 dB	Moderate rainfall
Strain Wave Gear	65 dB	Loud conversation / vacuum cleaner

On top of that, strain wave gears generate higher-pitched tones, which are more irritating. The Archimedes Drive emits a low, consistent hum—calm and unobtrusive.

This quiet profile makes the drive ideal for human-centric robotics and machines operating in shared spaces.

> Part 3: Speed: Lubrication, Temperature, and Untapped Potential

One often-overlooked aspect of drive design is maximum speed, which is heavily influenced by:

Heat generation
Lubricant performance
Material fatigue

Why Temperature Matters:

Lubricants start breaking down around 70°C (160°F)
Above this, even advanced traction fluids can burn, leading to failure

In real-world testing, IMSystems ran their Delta 15 Archimedes Drive up to the limits of their available test motors. At full RPM, the drive only reached 40°C, well below the danger zone. This means there’s still headroom—a faster version is entirely possible.

Competitive Insight:

Strain wave gears may reach 75,000 RPM (as seen in NASA’s rocket program)
However, they suffered metal fatigue—not lubricant failure
Archimedes Drives could likely exceed standard planetary drives in speed without overheating

It’s a promising sign for future high-speed applications, where reliability and temperature control are critical.

> Part 4: What’s Next?

Let’s walk through how this drive architecture improves upon both traction and compound drives:

In the next class, we’ll explore how the Archimedes Drive performs in terms of:

Torque vs. lifespan
Weight trade-offs
Overall drive system efficiency in real-world loads

We’ll also begin constructing a comparative framework to evaluate the Archimedes Drive against all major alternatives, both numerically and contextually.

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Archimedes Drive Working Principle

Casper van Eersel — Tue, 19 Aug 2025 00:00:19 +0000

ARCHIMEDES DRIVE Working Principle

Summary

After laying the foundation in the last two classes, the Archimedes Academy by IMSystems finally introduces the Archimedes Drive—a novel traction-based drive that blends the best of two worlds: planetary traction drives and compound (Wolfrom) drives. The result? A revolutionary mechanism that retains the advantages of both systems while eliminating their core disadvantages.

> Part 1: Recap: Why Combine Traction and Compound Drives?

Let’s quickly revisit the building blocks of the Archimedes Drive:

Planetary Traction Drives replace gear teeth with traction rollers, enabling low noise, no backlash, high efficiency, and smooth operation—but suffer from low gear ratios and complex mechanisms to prevent wear and fatigue.
Wolfrom Drives introduce a second planetary layer to achieve extremely high gear ratios and compact design, but they struggle with low efficiency, complex manufacturing, and high cost.

> Part 2: The Archimedes Drive: The Innovation

IMSystems envisioned replacing the gear-based torque transmission in a Wolfrom drive with traction rollers. That small but powerful switch gave birth to the Archimedes Drive, a planetary traction drive.

Key Concept: The Flexroller planets

At the heart of this innovation is the Flexroller—a hollow friction roller that integrates a step size. This design not only enables traction-based torque transfer but also allows for micron-scale control over gear steps—something gears can’t match.

This micrometric step difference enables ultra-high gear ratios in a single stage, while maintaining mechanical simplicity and compactness

> Part 3: Why “Archimedes”?

Archimedes famously said:

“Give me a lever long enough and a fulcrum on which to place it, and I will move the world.”

The Archimedes Drive quite literally applies this idea through its internal mechanical “lever” system, using the ground annulus as a fulcrum to transmit force from a small input to a much larger output.

> Part 4: Eliminating Disadvantages, Keeping Advantages

Let’s walk through how this drive architecture improves upon both traction and compound drives:

Property	Wolfrom Drive	Archimedes Drive
High Efficiency	(30% typical)
No Backlash	(gears introduce play)
Lightweight / Hollow Structure
Compact Design
High Torque Density
Manufacturing Simplicity		(uses smooth cylinders)
Controlled End-of-Life
High Gear Ratio		(Micron-scale step control)

> Part 5: Engineering Highlights

No planetary axles: The Archimedes Drive eliminates the need for stable axles in the planet wheels by introducing a second annulus gear as the grounded element.
No gear meshing: Replacing traditional gear teeth with smooth friction rollers simplifies alignment and reduces manufacturing costs.
Micron-level precision: With step size no longer tied to discrete gear teeth, engineers can precisely tune gear ratios by controlling roller geometry alone.

Conclusion:

The Archimedes Drive isn’t just another theoretical breakthrough—it’s a practical and scalable advancement in motion control. It solves the exact problems that have limited traction and compound drives for decades, making it a serious contender for next-gen robotics, aerospace, and industrial automation.

If you were impressed by traction or Wolfrom systems individually, the Archimedes Drive will feel like a culmination of mechanical design evolution.

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Archimedes Academy EP. 6: Compound Principle

Casper van Eersel — Tue, 12 Aug 2025 00:00:11 +0000

HOW DO COMPOUND DRIVES WORK?

Summary

In this sixth installment, we’re uncovering the intricate world of compound drives—a class of mechanical systems essential for achieving high torque density in compact spaces. Specifically, we’re focusing on one of the most fascinating examples: the Wolfrom drive.

Understanding these systems is key to grasping the innovations behind next-generation technologies like the Archimedes Drive, which we’ll explore in the next class.

> Part 1: What Is a Compound Drive?

A compound drive is essentially a multi-layered planetary gear system. Unlike standard planetary drives, which involve a single set of sun, planet, and ring gears, compound drives introduce additional moving layers to transmit torque and manipulate speed.

These layers can be arranged:

Radially – with wider outer rings
Axially – stacked vertically like a sandwich

This added complexity gives compound drives their name and their power.

> Part 2: The Wolfrom Drive: A Compact Compound Powerhouse

The Wolfrom drive is an elegant example of axial layering. Here’s how it works:

Multiple planet gears are fixed on a common axis.
These gears rotate at the same speed but have different gear tooth counts.
The drive includes an input sun gear, a grounded annulus, and an output annulus.
Torque transmission is spread across the layers, resulting in massive reduction ratios.

In simpler terms: the Wolfrom drive delivers powerful torque output without the need for bulky, stacked drives.

> Part 3: Gear Ratio and Lever Analogy

To understand how gear ratios are calculated in compound systems like the Wolfrom drive, think of it as a lever:

The ground acts as a fulcrum.
Torque is “leveraged” via the gear diameters.
The gear ratio becomes a product of:
- The diameter of the output annulus
- The planet gear size
- A “step” difference between layers

This system enables extremely high gear reductions, sometimes exceeding what’s possible with any other drive type.

> Part 4: Key Advantages of Compound (Wolfrom) Drives

Why would engineers choose a compound drive, and particularly a Wolfrom drive? Here’s what they gain:

High gear ratios in a single compact system
Exceptional torque density (torque-to-weight ratio)
Space-saving design, avoiding long drive trains
Ideal for robotics, aerospace, and precision machines

These features make the Wolfrom drive an engineering gem—when size, weight, and torque all matter.

> Part 5: The Catch: Limitations of the Wolfrom Drive

Despite its benefits, the Wolfrom drive isn’t widely used in everyday machinery. Why?

Complex manufacturing: Multiple interacting layers require extremely precise machining.
High cost: Precision = expensive tooling and quality control.
Low efficiency: Friction and backlash reduce efficiency to around 30%.
Noise and wear: Misalignments lead to unwanted vibrations and long-term wear.

In essence, it’s a powerful but niche technology—perfect for highly specialized applications but often impractical for mass production.

Conclusion:

So, how do compound drives work?

They manipulate torque and speed through multi-layered planetary gear systems, using clever mechanical layouts to achieve what traditional gearboxes can’t. The Wolfrom drive, in particular, showcases the power of compact design paired with high torque output.

But every innovation has trade-offs—and in the case of compound drives, it’s the balance between efficiency, cost, and complexity.

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History of Traction Drives

Casper van Eersel — Tue, 05 Aug 2025 00:00:11 +0000

history of traction driveS

Summary

This session focuses on traction drives—a unique, often overlooked alternative to traditional gear-based transmissions in robotics. The lecture covers their principles, mechanical properties, history, advantages, and limitations, serving as a foundational understanding before exploring the Archimedes Drive.

> Part 1: History of Traction Drives

1870s – Early Industrial Origins

First used in automated factory conveyor systems.
Featured discs and adjustable rollers for controlling conveyor belt speed.
Though clever, the application was narrow and remained niche.

1920s–1930s – Automotive Interest

As automobiles grew, gearless solutions were explored to avoid gear backlash and complexity.
Traction drives were studied but found lacking in reliability and performance, so gears remained dominant.

1970s – The Nasvytis Drive

NASA-backed research led to the invention of the Nasvytis Drive.
Designed as a planetary traction system:
- Two layers of planetary rollers were used to spread stress.
- Incorporated a torque-sensitive preloading system to adjust normal force.
Despite technical novelty, it was too complex and costly for commercial adoption.

Hollow Roller Concepts

Later, engineers explored hollow planetary rollers:
- Offered low weight, efficient stress distribution, and very high efficiency.
- But presented practical limitations:
  - Hollow structure made it impossible to run a stable central axis, essential for gear-grounding.
  - Although theoretically ideal, the design was impractical to implement in most machines

> Part 2: Terminology - FRICTION VS TRACTION, STRESS, METAL FATIGUE

Friction vs. Traction: What’s the Difference?

Friction involves resistance between sliding surfaces (static or kinetic).
Traction refers to rolling resistance created by contact pressure and motor-driven rotation—like a train on steel rails.
Traction aims to avoid kinetic friction and operate purely through rolling, enhancing efficiency and reducing heat/noise losses

Stress and Material Deformation

Definitions and Concepts

Stress = Force ÷ Cross-sectional area.
Causes strain (deformation), which is either:
- Elastic (returns to original shape), or
- Plastic (permanent change).

Hertzian Contact Stress

Occurs in rolling systems like traction drives or bearings.
Generates deep, localized stress at contact points.
Leads to subsurface microcracks that gradually cause surface pitting and degradation

Metal Fatigue & Failure

Even under elastic stress, repetitive cycles can cause metal fatigue.
Eventually leads to material failure, even without plastic deformation.
In gears, fatigue can cause sudden failure.
In traction drives, degradation is gradual, allowing predictive maintenance and controlled end-of-life scheduling.

> Part 3: Advantages and Disadvantages of a Strain Wave Gears

Feature	Benefit
High efficiency	Due to rolling rather than sliding contact
Low noise	No gear mesh noise
No backlash	Continuous contact, ideal for precision control
High max speed	Less heat, no lubricant breakdown
Lightweight (hollow)	Especially with hollow rollers (if feasible)
Controlled EOL	Gradual wear makes maintenance predictable

Limitation	Drawback
Low gear ratio	Can’t reduce speed/torque as much as gears
Short lifetime	Especially if poorly designed or stressed
Complexity	Preloading mechanisms add manufacturing cost
No stable axis (hollow)	Limits use in compound gearing systems

Conclusion:

The Nasvytis Drive and later hollow designs aimed to increase torque and efficiency, but tradeoffs in durability, cost, and mechanical feasibility limited their adoption. These designs remain important theoretical steps that informed the development of newer solutions like the Archimedes Drive.

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Archimedes Academy EP. 4: Planetary Drives

Casper van Eersel — Tue, 22 Jul 2025 00:00:46 +0000

Planetary Drive Working principle

Summary

Welcome to the fourth class of the Archimedes Academy by IMSystems. In previous lessons, we discussed the three most common drive types used in robotics. Last time, we covered cycloidal and strain wave gears. Today, we will explore planetary drives, one of the oldest gear mechanisms, dating back to hundreds of years BC. While originally designed to simulate the solar system’s motion, planetary drives have become integral to modern mechanical systems, including robotics.

> Part 1: Components of a Planetary Drive

Planetary drives are named for their resemblance to a planetary system. The key components include:

Sun Wheel: The central gear, which serves as a primary input or output component.
Planetary Wheels: Multiple gears that revolve around the sun wheel.
Carrier: Holds the planetary wheels in place and ensures equal spacing.
Annulus (Ring Gear): The outer gear encircling the planetary wheels.

Understanding these components is essential before diving into how the drive functions.

> Part 2: Fundamental Physics: Moments and Torque

To grasp planetary drives, we must first understand the concept of moments (or torque). Torque is calculated as force × distance, defining the rotational force applied to a system.

A common example of moment balancing is a seesaw, where weights and distances determine equilibrium. This principle extends to levers, categorized into three types:

Class 1: Fulcrum in the center (e.g., seesaw, pliers).
Class 2: Load in the center with the fulcrum at the end (e.g., wheelbarrow).
Class 3: Effort applied in the center (e.g., tweezers, certain muscle movements).

Similarly, gears function as rotational levers, transmitting force over distances to achieve mechanical advantage.

> Part 3: How Does a Planetary Drive Work?

Planetary drives operate through variable component roles. There are always three key roles in motion:

Input: The driving force (e.g., sun gear, carrier, or annulus, depending on configuration).
Output: The component transferring torque to the load.
Ground (Fixed Component): Provides stability and enables gear movement.

Several configurations can be used:

Fixed annulus: The sun wheel acts as the input, and the carrier functions as the output.
Fixed sun: The carrier becomes the input, and the annulus serves as the output.
Fixed carrier: The sun is the input, and the annulus becomes the output.

Gear Ratio Calculation

The gear ratio in a planetary drive is determined based on component engagement. For the most common configuration where the annulus is fixed, the gear ratio is:

Gear Ratio = (Number of Teeth on Annulus) / (Number of Teeth on Sun Gear)

This ratio impacts torque transmission and rotational speed.

> Part 4: Advantages and Disadvantages of Planetary Drives

Advantages:

Cost-Effective: Planetary drives are relatively inexpensive, making them popular in hobby robotics.
High Efficiency: They offer efficiencies between 90-99%, reducing energy losses.
Backdrivability: They can be reversed easily, even across multiple stages.
High Torque Density: They provide significant torque for their size.

Disadvantages:

Low Precision: High backlash limits their application in precision systems.
Limited Gear Ratios: Typically between 5:1 and 30:1; achieving higher ratios requires stacking multiple stages.
Noise: Planetary drives can be quite loud during operation.
Durability and Maintenance: High wear and frequent maintenance are required for extended operation.

Conclusion:

Planetary drives provide an efficient and cost-effective solution for many applications but are not ideal for high-precision robotics due to backlash and limited gear ratios. This concludes our discussion on the three major drive types in robotics—cycloidal, strain wave, and planetary drives. The next classes will focus on the Archimedes Drive, exploring its unique capabilities and advantages.

Thank you for reading, and stay tuned for the next session!

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Archimedes Academy EP. 3: Strain Wave Gear (Harmonic Drive)

Casper van Eersel — Tue, 15 Jul 2025 00:00:58 +0000

Strain Wave Gear Working principle

Summary

Welcome to the third class of the Archimedes Academy by IMSystems. In this series, we are exploring the three most common drive types used in robotics. In the previous lesson, we discussed the cycloidal drive. Today, we will focus on the strain wave gear, also commonly known as the harmonic drive, named after the company that pioneered its commercialization.

> Part 1: How Does a Strain Wave Gear Work?

The strain wave gear has been in use for over 50 years and consists of three main components:

Wave Generator (Input): This elliptical component deforms the flexspline to engage with the circular spline.
Flexspline: A thin, flexible cup with external gear teeth that deforms to fit into the circular spline.
Circular Spline (Output): A rigid ring with internal teeth that meshes with the flexspline.

Working Principle

The wave generator is placed inside the flexspline and is elliptical in shape.
As it rotates, the flexspline is deformed in a way that forces its teeth to engage with the circular spline at two opposite points.
Because the flexspline has fewer teeth than the circular spline, each full rotation of the wave generator results in a slight rotational movement of the flexspline relative to the circular spline.
This results in a high gear reduction ratio with minimal backlash.

The gear ratio of a strain wave gear is calculated using:

Typically, the difference is two teeth, leading to very high gear ratios such as 360: 1 or more.

> Part 2: Terminology - PRECISION VS. ACCURACY, LOST MOTION, BACKLASH

Understanding the terminology is essential when discussing precision in robotic drives.

Precision vs. Accuracy:

Accuracy refers to how close a system’s motion is to a desired target position.
Precision refers to the repeatability of achieving the same position over multiple attempts.
A system can be highly accurate but not precise, or highly precise but not accurate.

Lost Motion and Backlash:

Lost Motion: The deviation between the commanded motion and actual motion due to various factors such as backlash and flexibility.
Backlash: The small gap between mating gears, leading to undesired play in movement. It is one of the primary contributors to lost motion.
Rotational Stiffness: The resistance of a component to deformation under load, affecting motion accuracy.

The strain wave gear is nearly backlash-free, making it one of the most precise drive systems available.

> Part 3: Advantages and Disadvantages of a Strain Wave Gears

Advantages:

High Torque Density: Offers a high torque-to-weight ratio, especially in low torque applications.
Extremely High Precision: One of the most precise drive systems available due to minimal backlash.
High Gear Ratios: Can achieve very high reduction ratios (e.g., 360:1), surpassing most other drive types.
Backdrivability: Can be backdrivable at low gear ratios, allowing energy efficiency in certain applications.

Disadvantages:

Expensive: More costly than most other drive types, including cycloidal drives.
Limited Durability: Prone to wear and tear due to the flexible spline.
Higher Maintenance Requirements: Requires regular maintenance for optimal performance.
Lower Efficiency: Generally lower mechanical efficiency (~70-80%) compared to other gear types.
Noise Generation: Produces high-pitched noise, which can be bothersome in environments where workers are present.

Conclusion:

The strain wave gear is a widely used drive in robotics due to its unmatched precision and high gear ratios. However, it comes with trade-offs in durability, cost, and efficiency. In the next lesson, we will explore planetary gears and their applications in robotic systems.

If you have any questions or comments, please leave them below. See you in the next class!

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