Sensorless Position Control

And the cost is showing up in reliability, sanitation, and capital spend.

The Hook

Servo systems didn’t come from food manufacturing.

They came from machine tools and robotics, a world that demands 0.001° positioning, high RPM, and tight feedback loops.

Food manufacturing didn’t need that. Food manufacturing needed reliability, hygiene, and total cost control.

But the industry adopted the servo stack anyway, and we’ve been paying for it ever since.

The Servo Stack Is a Chain of Compensations

A servo system isn’t one product. It’s a stack:

High-speed PMSM servo motor
Encoder for feedback
Planetary gearbox to convert speed into torque
Servo drive to manage the loop

Each piece exists to solve a problem caused by the previous piece.

That’s not engineering elegance. That’s architectural debt.

And in food manufacturing, especially washdown, it shows up as:

Encoder failures
Gearbox seal wear
Sanitation risks
Expensive stainless variants
High spare parts inventory
Downtime during sanitation-sensitive failures

The Reframe

The right question isn’t:

“How do we make the servo stack cleaner and more reliable?”

The right question is:

“Do we even need the stack?”

That’s where One Motion changes the conversation.

DDRM + Lenze i650: A Different Architecture

One Motion DDRM (Direct Drive Rotary Motion) is a large-diameter PMSM built to deliver torque directly to the shaft. No gearbox, no speed-to-torque conversion, no compromise.

Pair it with the Lenze i650 sensorless inverter, and the system becomes:

Encoderless
Gearbox-free
Sensorless vector controlled
Hygienic by design

This isn’t a smaller, cleaner servo system.

It’s a fundamentally different architecture.

So How Does the i650 Know Where the Rotor Is Without an Encoder?

This is the question every serious engineer asks. The answer is the technical backbone of the entire architecture.

The Lenze i650 uses SLPSM (SensorLess control of Permanent Synchronous Machine), a control technique that reconstructs rotor position in real time using a mathematical model of the motor and measured electrical signals.

It doesn’t measure the rotor. It calculates it.

The Motor Model Inside the Drive

The drive carries a digital twin of the motor in firmware:

Stator resistance
Stator inductance (Ld, Lq)
Back-EMF constant
Pole pairs
Rated voltage and frequency

The i650 measures two things continuously:

Stator currents (Iu, Iv, Iw)
Stator voltages (commanded by the drive)

It runs these through the model and back-calculates where the rotor must be for the measured electrical behavior to be physically possible.

This is Field-Oriented Control without a sensor.

Two Operating Regions (This Is the Engineering Art)

The physics of sensorless estimation changes with speed, so the i650 runs two different strategies.

At standstill and very low speed:

There is almost no back-EMF
The drive injects a controlled current
The rotor is pulled into a known reference position
Motion begins from a known angle

Lenze’s newer firmware also includes pole position identification without motion, which locks the angle before any movement, eliminating start-up jerk. Critical when a DDRM starts with product already on the belt.

At medium and higher speed:

Back-EMF becomes strong enough to observe
The drive switches to a closed-loop back-EMF observer
The observer locks onto the rotor flux angle
Speed is derived from angle change over time

This is true Field-Oriented Control: only the current required for the demanded torque is injected, and rotor position is tracked continuously.

The Observer in Plain Terms

The observer is the math at the heart of sensorless control:

Measure the actual current
Predict what the current should be based on the model
Compare actual vs predicted
Use the error to estimate back-EMF
From back-EMF, calculate rotor angle
From rotor angle over time, calculate speed

The result is real-time rotor tracking using nothing more than the electrical signals already inside the drive.

No encoder. No feedback cable. No alignment.

Why This Works So Well With DDRM

Sensorless control is hardest at high RPM with narrow torque margins. That is servo territory, which is exactly why servos need encoders.

Sensorless control is easiest at low RPM with wide torque margins. That is DDRM territory.

The large-diameter PMSM rotor in DDRM produces:

Strong back-EMF at low speed
High signal-to-noise ratio for the observer
Stable estimation under load changes

DDRM operates exactly where the i650’s observer is most accurate and most stable.

This isn’t a workaround. It’s a physics match.

The Reliability Math (Field Reality)

Reliability isn’t earned by adding protection. It’s earned by removing components, and the field data proves it.

In washdown food environments:

Servo systems average ~1 year of service life before encoder, gearbox seal, or feedback failures force replacement or rebuild.
One Motion DDRM averages 5+ years of service life, with no encoder to fail and no gearbox to wear.

That’s not a small improvement. That’s a 5× lifecycle multiplier.

What This Means at Fleet Scale

For a plant running 1,000 motion axes:

Servo stack (1-year life):

~1,000 replacements over 5 years
Continuous spare parts consumption
Recurring sanitation-driven downtime
Ongoing capital reinvestment

DDRM + i650 (5-year life):

~200 replacements over 5 years
Minimal spare parts churn
Predictable maintenance cycles
Capital deployed once, not annually

That’s an 80% reduction in motion system replacements over a 5-year horizon.

Why the Gap Is So Large

It comes back to architecture:

Servo systems fail at their weakest layer: encoder, gearbox seal, or feedback cable.
DDRM has no weakest layer: no encoder, no gearbox, no wear-driven mechanical interface.

Reliability isn’t a feature you add. It’s a result of what you remove.

Washdown Servo Is Structurally Expensive

The cost stacks at every layer:

Stainless servo body
Hygienic encoder housing
Stainless planetary gearbox
Washdown cabling
Specialty connectors

This isn’t a pricing problem. It’s an architecture problem.

DDRM removes the architecture that requires those premium parts in the first place.

Total Cost of Ownership Tells the Real Story

A servo system has hidden costs:

Encoder replacements
Gearbox oil service
Multi-SKU spare parts
Specialized service labor
Sanitation-driven downtime

DDRM + i650 changes the curve:

One motor SKU
One drive SKU
No oil
No encoder
Standardized service

For food manufacturers running 24/7 shifts, this isn’t a 10% improvement.

It’s a structural cost reset.

The Big Picture

Direct-drive disruption has already happened in other industries:

Tesla vs combustion drivetrain
Solid-state drives vs hard drives
Direct-drive washing machines vs belt-driven

In each case, the disruptor didn’t make the old architecture better. They removed the layers that justified it.

One Motion is doing the same thing for food manufacturing motion.