Why SimCraft Feels Real:
Rigid Body Motion Simulator
with
Center of Mass Precision

Motion Cueing and Human Perception: The Subconscious System at Work

As outlined in Phillip Denne’s white paper Motion Platforms or Motion Seats, humans don’t just see motion—they feel it before they even realize it. Our bodies respond to acceleration via:

• Tactile feedback from skin pressure
• Vestibular response in the inner ear
• Proprioception, our sense of body position

Cue Conflict and Sensory Mismatch

When a simulator provides visual movement but incorrect or delayed physical motion, the brain quickly flags the inconsistency. This leads to:

• Simulator sickness
• Training fatigue
• Distrust in motion inputs

Even worse, if a driver does begin to trust the simulator, but the motion is wrong, it results in building the wrong reactions. This is especially dangerous in motorsport contexts, where instinctual responses decide outcomes in fractions of a second.

Timing Is Everything

Good simulators don’t just move realistically—they move immediately. Research in motion perception indicates that humans detect tactile change faster than visual change. SimCraft’s low-latency electromechanical architecture ensures that the physical sensation of corner entry hits before the visuals catch up, just like in a real car.

Analogy: Where You Feel It Matters

When you drive a real car, you don’t just see a turn—you feel it. The shift of weight, the pull against your body, the pressure into the seat.

Most simulators miss that critical connection. They move parts of the rig, but not the way a real vehicle moves, leaving your instincts out of sync.

SimCraft rotates the entire cockpit around your center of mass, delivering motion exactly where your body expects it—building real reactions, not just reactions to a screen.

The Problem with Traditional Motion Platforms

Stewart Hexapod Platforms: Synergy or Shortcut?

The Stewart platform, a common six-degree a.k.a. Hexapod motion rig, uses linear actuators in a triangular configuration to produce multiple movements. However, these come with trade-offs:

• All axes are mechanically linked, so movements like roll, pitch, and heave can’t operate independently. This creates unnatural combinations of motion that the brain quickly flags as wrong—leading to cue conflict, motion sickness, or both.
• Motion is limited by range, requiring frequent re-centering that disrupts continuity and breaks immersion.
• Input commands interfere, where one axis affects another—like pitch unintentionally inducing roll—compromising motion fidelity.

That kind of motion might suffice in a jetliner where everything happens slowly—but race cars don’t fly level. They twitch, snap, and rotate violently. If your platform can’t keep up with that reality, it’s not simulation—it’s misdirection.

Brute Force Platforms: D-BOX, SPX, and Similar Systems

Another common approach in the sim racing industry is the use of brute-force actuator platforms like D-BOX or the SPX motion rigs. These systems rely on linear actuators bolted beneath the rig or chassis pushing off the floor, delivering sharp vertical or longitudinal jolts to simulate track features or motion changes.

These approaches have critical flaws when viewed through the lens of rigid body dynamics:

• Actuation occurs far from the center of mass, introducing unnatural torque vectors
• Motions are high energy but not directionally accurate
• Simulated effects are often pre-programmed (canned) effects, not true motion physics
• The system often mimics motion by forcing movement rather than simulating a physical interaction with real-world mass

The result is often sensory overload that may feel dramatic but is disconnected from real car behavior. Instead of training a driver’s instincts, brute-force platforms risk conditioning false responses—overcorrecting slides, overestimating grip, or reacting late to oversteer because the motion cue arrives after the fact.

As research from military and aerospace simulators has shown, intensity cannot replace accuracy. Without center-of-mass alignment and rotational integrity, the entire simulation becomes theater.

Seat Movers: Misaligned Intentions

Some simulator systems attempt to cue motion by physically tilting or shifting the driver’s seat within a fixed cockpit. The idea is to simulate G-forces by making the seat pan/back move in relation to the driver’s body—forward for braking, backward for acceleration, and side-to-side for cornering.

While this can produce some motion sensation, particularly in low-amplitude applications like driver entertainment or entry-level training, it introduces several fundamental problems:

• Seat motion is disconnected from the cockpit environment—breaking the illusion of a rigid body system.
• Motion is isolated to the torso, lacking full-body cues that align with vehicle dynamics.
• The control interface remains static, which introduces proprioceptive conflict between limbs and surroundings.

Moving only the seat inside a stationary cockpit violates a foundational principle of simulation: that the entire cabin should move as a unit. This decoupling leads to cue conflicts and undermines the realism needed for instinctive driver development.

G-Seats: Pressure Without Presence

G-seats aim to simulate sustained acceleration by altering pressure on the driver’s body—typically through small actuators with moving panels in the seat base and backrest. Originally developed for military aviation, their goal is to replicate the feel of G-forces through localized compression rather than physical movement.

While theoretically compelling, most G-seat designs suffer from critical limitations:

• False feedback: G-seats do not replicate chassis rotation or translation, meaning they cannot convey car attitude changes like yaw or heave.
• Limited scope: G-seats simulate pressure, not motion—they cannot replicate rotation, translation, or inertial torque.

They may feel convincing for vibration or shock, but they lack the full-range motion fidelity needed to train the subconscious reflexes used in motorsport.

Why These Systems Fail in Ground Vehicle Simulation

SimCraft’s founder Sean Patrick MacDonald describes it clearly: cars move, twist, rotate, and snap. When a simulator doesn’t pivot from the same place the car would, it creates an illusion—but not a simulation.

You can’t trick the subconscious, you have to respect the body’s perception of center-aligned force.

Tuning Motion to the Brain: Perception Is the Final Layer of Realism

The Brain Doesn’t Read Numbers—It Reads Sensation

Even if a simulator is mechanically perfect, perception isn’t. The human brain filters motion based on context, sensitivity, and threshold. If the cue is too sharp, too faint, or out of sync with expectation, the brain either downplays it—or mistrusts it altogether.

The goal isn’t to overwhelm. It’s to match motion to what the brain expects at that exact moment in time. That’s why tuning matters.

Thresholds, Filters, and the Wipeout Effect

The vestibular system is built with a high-pass filter. It ignores low-amplitude motion and quickly adapts to sustained cues. At the same time, overly abrupt motion can feel jarring, misleading the brain’s interpretation of what’s happening.

Properly tuned motion strikes the balance—strong enough to be felt, subtle enough to be trusted. If it’s too much, it feels artificial. Too little, and it’s ignored.

Why SimCraft Systems Are Tunable by Design

Unlike most motion platforms, SimCraft systems are built with deep per-axis tuning controls. Every SimCraft simulator can be adjusted to the unique way a driver perceives motion:

• Change real-time while you are driving or flying
• Adjust amplitude per axis (roll, pitch, yaw, surge, sway, heave)
• Roll and pitch tuning of interactive response to the virtual world (such as hills, curbs, etc)

This allows engineers, coaches, or the driver themselves to dial in motion that the brain recognizes as real—because it behaves the way the driver expects it to.

Realism Isn’t Max Output—It’s Right Output

More movement isn’t more realism. Better movement is.

The final link in a motion simulator isn’t just the rig or the software—it’s the brain interpreting the input. Tuning ensures the simulator matches not only physics—but perception. That’s what separates SimCraft from everything else.

SimCraft’s Architecture: Independent Degrees of Freedom Around a Fixed Mass

Gimbal-Based Motion Around Center of Mass

At the heart of SimCraft’s design is a multi-axis gimbal system—a mechanical structure purpose-built to pivot around a single point: the center of mass. Instead of pushing the chassis from a fixed frame or jolting it with actuators, SimCraft mounts the entire driver capsule—seat, controls, monitors, and driver—onto a set of independently rotating frames, each corresponding to a single rotational degree of freedom (DoF).

This is not simulated motion—it’s real rotational movement, through true pitch, roll, and yaw, all centered around the same axis that a car uses in real life.

Because each axis moves independently, there’s no conflict or compromise. A yaw input doesn’t bleed into pitch. A rapid roll doesn’t fight against surge. That’s a key distinction: motion is uncoupled, respecting the physics of rigid body mechanics, and not altered by mechanical interference.

Why This Architecture Matters

Here’s where everything comes together:

• Pitching forward under braking rotates the entire chassis down, pivoting around the center of gravity—just like a car.
• Losing the rear in a fast corner triggers real yaw and roll, not a visual slide paired with a seat shake.
• Transitions feel smooth and physically complete—not a staccato mix of conflicting actuators.

This motion model preserves mechanical integrity, allowing drivers to feel what they see and react before they think. That reaction time—measured in milliseconds—is where instincts are trained and decisions become automatic.

Electromechanical Precision

SimCraft’s system uses direct-drive electromechanical actuation, not hydraulics or pneumatics. This means:

• Lower latency
• Higher precision in micro-movements
• Minimal maintenance
• Quiet operation—ideal for training or high-fidelity home use

No high-pressure oil systems, no heat generation, and no re-centering drift. Every motion event is consistent, repeatable, and matched to the physics engine’s calculations of what the vehicle is doing in space.

Translational Seat Time: Why Precision Cues Create Transferable Skill

What Is Translational Seat Time?

Translational seat time is the holy grail of simulator-based driver training. It refers to time spent in a simulator that translates directly to improved performance in a real car. To achieve this, the simulator must train both conscious decision-making and subconscious muscle memory.

Without realistic motion cues, a simulator might teach you the track—but it won’t teach you how to drive it.

Building Correct Muscle Memory

When motion cues are accurate—aligned in timing, direction, and intensity with real-world expectations—drivers form the same physical and neurological patterns they’d develop on track. This includes:

• Brake timing
• Throttle modulation during load transfer
• Correction during mid-corner oversteer
• Anticipating grip loss through body feel, not visuals

This is why SimCraft’s racing simulators are used not just for entertainment, but as driver development tools for professional racers, engineers, and driver training programs.

When Cueing Is Wrong, Learning Becomes Unlearning

The danger of simulators that fail to align with rigid body principles is subtle—but serious. When a driver begins to trust motion cues that are directionally wrong or temporally delayed, they build habits that work in the simulator—but fail on track. For instance:

• A delayed sway cue trains the driver to lift too late when grip breaks, reducing reaction time in real-world transitions.
• A pitch-down signal from an off-axis rotation (common in seat movers or non-CoM platforms) can feel like oversteer instead of braking—reinforcing the wrong corrective instinct.
• Misaligned yaw—especially when induced from the front or through blended actuation—can teach overcorrection habits during slides or turn-in phases.

Correcting these habits later requires more effort than learning correctly the first time. Wrong motion cues increase cognitive load, reducing decision-making quality and delaying response time.

Misconceptions About Motion Simulation

Let’s tackle some persistent myths head-on.

Myth: “More Motion Means More Realism”

It doesn’t. In fact, too much motion from the wrong location makes things worse. Brute-force systems can be thrilling, but they disrupt cue timing and magnitude. The human nervous system filters out motion it doesn’t trust, meaning more motion can be ignored entirely—or worse, it actively trains the wrong response.

Myth: “Visuals and Force Feedback Are Enough”

They help, but not alone. Visual response is delayed compared to tactile and vestibular input, meaning you’ve already reacted to motion before your eyes catch up. No amount of 4K rendering or force feedback torque can replace the subconscious understanding that comes from physically feeling the car rotate, surge, and sway.

Myth: “All 6DOF Platforms Are the Same”

They’re not. A Stewart hexapod platform is mechanically limited. A D-BOX or SPX platform applies linear jolts. SimCraft’s system applies rotational motion at the exact same physical point where the real car would rotate. That’s not just more realistic—it’s mathematically correct.

Myth: “The Monitors Don’t Need to Move”

They do. In the real world, your visual frame of reference moves with you—your eyes, your seat, and your windshield are all part of the same rigid body. When the cockpit moves but the screens stay fixed, it creates a visual-vestibular mismatch that breaks immersion and forces your brain to work harder to reconcile the disconnect.

SimCraft solves this by allowing monitors to move with the chassis, maintaining alignment between what your body feels and what your eyes see. This is critical for maintaining realism and reducing cognitive load during training.