PDK 6-DoF Technology
The Patent Protected (CA 3217174 C) ARK PDK system represents a fundamental breakthrough in motion simulation technology. Built on our patented ajustments to the Stewart platform architecture, this six degrees of freedom (6-DoF) parallel robot eliminates the compromises of traditional motion systems, delivering unprecedented performance .
Precision, Power & Potential
System Architecture
Platform Design:
Stewart platform with six independent actuators, enabling full 6-DOF motion:
Degrees of Freedom (6-DOF):
Full six-axis motion:
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Translational: Sway (X), Surge (Y), Heave (Z).
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Rotational: Pitch (A), Roll (B), Yaw (H).
Normal Motion Envelope: Sway 149.2 mm, Surge 163.6 mm, Heave 117.3 mm, Pitch 16.0°, Roll 17.3°, Yaw 20.3°.
Industry-Leading Performance
Unprecedented Latency
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1.4 milliseconds from signal input to discernible motion output one of the lowest latencies currently advertised in motion simulation. This matters because human brains perceive motion cues faster than visual ones. Our system responds faster than visual displays, creating natural, comfortable simulation without motion sickness.
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Future improvements target sub-millisecond territory, further advancing the state of the art.
Exceptional Bandwidth
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400 Hz frequency response versus 20-100 Hz for traditional systems. This four-fold improvement means ARK PDK reproduces motion signals at frequencies impossible for previous-generation platforms.
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Think of the difference between AM radio and CD-quality audio that's the fidelity improvement our bandwidth delivers for motion simulation.
Exceptional Motion Envelope
Coordinate System
The platform uses a right-handed coordinate system with three translational movements (Surge front/back, Sway side-to-side, Heave up/down) and three rotational movements (Yaw around vertical, Roll around longitudinal, Pitch around transverse axes).
Motion Capabilities
Nominal Motion Envelope (single-axis limits):
Motion
Surge
Sway
Heave
Pitch
Roll
Yaw
Range
-85.85mm to +77.84mm
±74.64mm
±58.68mm
-8.09° to +7.98°
±8.68°
±10.17°
Total Span
163.69mm
149.27mm
117.35mm
16.07°
17.36°
20.35°
Extended Motion Envelope (combined-axis operation):
Motion
Surge
Sway
Heave
Pitch
Roll
Yaw
Range
-96.56mm to +94.85mm
±103.54mm
±58.62mm
-10.50° to +10.80°
±9.72°
±10.95°
Total Span
191.41mm
207.09mm
117.24mm
21.30°
19.44°
21.91°
Advanced Envelope Analysis
We determined the extended envelope through comprehensive analysis of many joint parameter combinations using our Forward Kinematics algorithm, generating a massive dataset. This analysis confirmed the absence of singularities, with minimum leg-to-platform angles.
Revolutionary Forward Kinematics
Stewart platform Forward Kinematics has challenged roboticists for decades. Our breakthrough algorithm transforms parallel robot control:
Random Pose Calculation:
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207 μs average
Sequential Pose Processing:
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109 μs (9,174 calculations/second)
Precision:
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Double precision arithmetic with 1E-14 accuracy
GPU Performance:
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>1,200,000 calculations/second on Nvidia Quadro M6000
This innovation enables advanced Task Space control architectures previously impossible with parallel manipulators, opening new possibilities for sophisticated motion control strategies.
Sophisticated Motion Control
High-Performance Control Architecture
Motion control operates in Joint Space using a decentralized PID control structure. Six independent linear controllers work in feedback configuration, with each servomotor providing real-time position data through its high-resolution encoder.
The system processes six-dimensional trajectory streams using our optimized Inverse Kinematics algorithm, calculating precise joint positions transmitted to individual controllers at exceptional speeds:
Control Loop Rate:
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8,000 Hz (125 μs period)
Processing Power:
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Dual ARM Cortex-M7 @ 600 MHz
The 21-bit encoders provide 0.00017166° resolution—over 2 million divisions per revolution. This directly translates to remarkable platform positioning accuracy:
Axis
Surge
Sway
Heave
Yaw
Pitch
Roll
Minimum Resolution
0.002059 mm
0.000475 mm
0.000198 mm
0.000027°
0.000064°
0.000299°
Why Ultra-High Resolution Matters
In closed-loop control systems, encoder resolution and sampling rate directly influence system stiffness—the ability to react to disturbances and correct errors instantly. Higher resolution and sampling rates create greater stiffness, enabling faster, more precise corrections.
This is how a 14-bit encoder compares to a 21-bit encoder in terms of resolution and sensing of actual data:
Performance Highlights
Precision
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400Hz motion updates and 21-bit encoders ensure pinpoint accuracy—down to the millionth degree.
Power-to-Size Ratio:
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30kW peak in a 1m² footprint—unmatched compactness for its strength.
Immersion:
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Levitation-like control via pneumatics and high-torque motors—feels like defying gravity.
Efficiency:
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Energy recuperation system reduces losses, making it sustainable for long sessions.
High-performance Motor Control
Three dual-channel BLDC motor controllers (56V, 90A per channel) manage all six servomotors using Field-Oriented Control (FOC) for maximum efficiency. These controllers also host the closed-loop position controllers within our decentralized PID structure.
Communication Architecture:
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Motor controller ↔ Encoder: SPI
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Motor controller ↔ System: CANbus
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Inter-system: 100 Mbit Ethernet
Cutting-edge Control Intelligence
Dual-Processor Architecture
System Management (HKP):
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ARM Cortex-M7 handling system management, housekeeping, and Inverse Kinematics calculations
Motion Cueing (MCP):
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ARM Cortex-M7 processing external motion signals and generating trajectory streams
Both processors operate as bare-metal systems (no operating system) for maximum performance and minimum latency, communicating via 100 Mbit Ethernet through the integrated Wi-Fi router/switch.
Processing Capabilities
Motion Cueing DSP Loop:
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20,000-40,000 Hz (up to 50,000 Hz maximum)
Autonomous Operation:
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No external computer required
Signal Input Rates:
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>5,000 Hz across multiple formats
Communication Options:
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Ethernet, UART, Serial/USB, CANbus, I²C
Technical Features
Servo Motors:
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Direct-drive design with modified hoverboard motors—high torque, low latency, and maintenance-friendly.
Control System:
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Advanced motion controller with proprietary software (details TBD—likely supports custom integration).
Mounting:
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Bolted base for stability under 3G forces; optional weighted setup less recommended.
Applications:
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Simulates terrestrial, aerial, and marine vehicles with full 6-DOF granularity.
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Ideal for VR gaming, robotics testing, flight/driving sims, and experimental builds.
Precision Servomotors
Our custom 132mm brushless DC (BLDC) outrunners deliver exceptional performance:
Configuration:
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3-phase outrunners with reinforced shafts
Power Rating:
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56V operation, Kv 13.5
Motion Range:
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47mm crank radius (equivalent to 94mm stroke linear actuator)
Encoder Resolution:
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21-bit rotary absolute magnetic encoders
Sampling Rate:
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>100 kHz capability
The system uses six directly coupled servomotors for precise platform positioning and movement. Three additional pneumatic cylinders provide automatic weight compensation, creating a total of nine connection points between the moving platform and stationary base—technically making this a nonapod (nine-legged) configuration.
Since the pneumatic cylinders operate passively during motion, the system maintains the classic Stewart platform's non-redundant structure—six actuators for six degrees of freedom. All nine legs connect to the platform and base through ball joints, arranged in three symmetrical clusters of three connection points each.
To maximize ball joint range of motion, enhance kinematic stability, and reduce the overall system footprint, the motors and pneumatic cylinders are strategically tilted from vertical alignment.
Game-Changing Weight Compensation
The Direct-Drive Challenge
Traditional motion platforms use reduction gears that naturally support weight with minimal motor torque. A typical ball-screw actuator motor needs only 0.22Nm to counteract 250N of weight. The same load requires 11.75Nm from a direct-coupled motor - a 53× increase in torque requirement.
Our Solution
The Weight Compensation System automatically handles this challenge through three pneumatic cylinders working with our control system:
Operating Pressure:
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7.0 bar maximum
Cylinder Specifications:
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50mm bore, 140mm stroke with linear bearings
Auxiliary Systems:
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Dual dead volume tanks per cylinder
Control:
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Automatic load monitoring with real-time adjustment
Advanced Pressure Stabilization
Each cylinder features two auxiliary dead volume tanks that dramatically improve performance. Without these tanks, pressure fluctuation would be 5.03 bar across the cylinder's travel. With the auxiliary tanks, fluctuation drops to just 0.36 bar—more than 14× improvement.
The system continuously monitors moving mass load and distribution, actively adjusting air pressure only when needed, whether the platform is static or in motion. This keeps full motor torque available for motion rather than weight support.
Intelligent Power Management
Adaptive Power Architecture
Power Supply Unit:
3kW universal input capability
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Input: 100-290VAC, 47-63Hz
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Output: Up to 53.5VDC
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Power: 1,400W (low voltage) / 3,000W (high voltage)
Power Bank System:
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Three 63V, 0.47F aluminum electrolytic capacitors with copper bus-bar interconnection
Why Power Banking Matters
Motion simulation involves constant directional changes and acceleration bursts across all six axes. These movements require power pulses rather than constant supply.
Our power bank provides instantaneous power delivery exceeding 30kW while storing recuperated energy, enabling performance levels far beyond the 3kW supply unit alone. This architecture perfectly matches the burst-power nature of motion simulation.
Why Ultra-High Resolution Matters
The 21-bit encoders provide 0.00017166° resolution—over 2 million divisions per revolution. This directly translates to remarkable platform positioning accuracy:
Axis
Surge
Sway
Heave
Yaw
Pitch
Roll
Minimum Resolution
0.002059 mm
0.000475 mm
0.000198 mm
0.000027°
0.000064°
0.000299°
In closed-loop control systems, encoder resolution and sampling rate directly influence system stiffness—the ability to react to disturbances and correct errors instantly. Higher resolution and sampling rates create greater stiffness, enabling faster, more precise corrections.
21-Bit vs. 14-Bit Encoders: Precision in Motion Control
Encoders are critical components in motion simulation systems, translating physical motion into digital signals for precise control. The resolution of an encoder, measured in bits, determines the granularity of positional data it can provide. Below, we compare 21-bit and 14-bit encoders to highlight their differences and implications for high-performance applications like the Portal Development Kit (PDK).
Resolution and Positional Accuracy
• 14-Bit Encoder:
• Resolution: 2¹⁴ = 16,384 discrete positions per revolution.
• Angular Precision: Approximately 0.022° (360° ÷ 16,384). This translates to a fine but limited granularity for detecting rotational position.
• Application Fit: Suitable for applications requiring moderate precision, such as consumer-grade motion platforms, basic robotics, or less demanding simulation setups. For example, a 14-bit encoder can reliably track motion in systems where sub-degree accuracy is sufficient.
• 21-Bit Encoder:
• Resolution: 2²¹ = 2,097,152 discrete positions per revolution.
• Angular Precision: Approximately 0.00017° (360° ÷ 2,097,152), over 100 times finer than a 14-bit encoder.
• Application Fit: Ideal for high-precision applications like professional motion simulation (e.g., PDK’s 6-DOF platform), aerospace training, or advanced robotics. The ultra-fine resolution ensures smooth, lag-free motion tracking, critical for immersive experiences with a 400Hz motion update rate and 1kHz control loop.
Safety and Monitoring
Six millimeter wave (mmWave) presence sensors provide 360-degree environmental monitoring, while the User Interface microcontroller delivers essential system controls and status information.
Optimal Payload Design
Payload Capacity
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Up to 250kg (550 lbs) supports heavy loads (e.g., users, gear, or custom rigs) with levitation-like fluidity.
Compact Footprint:
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1000mm diameter × 500mm height (fully retracted)
System Configurations
Basic (PDK) Configuration
This is the core motion platform without any additional options:
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What it includes: The complete 6-DoF motion platform with flat-top design
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Mounting method: Designed to be bolted directly to the ground/floor
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Use case: Permanent installations where you have access to structural mounting
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Customization: The flat top can accept any user-provided superstructure (racing seat, flight sim cockpit, VR setup, etc.)
PDK + Extension Feet:
Portable professional platform
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Can be moved between locations
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No permanent installation required
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Accepts any custom superstructure
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Use case: Renters, temporary setups, or situations where permanent mounting isn't possible
PDK + Cockpit
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Permanent racing installation
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Bolted to ground for maximum stability
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Ready-to-use racing setup
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Professional racing simulation configuration
PDK + Extension Feet + Cockpit
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Ultimate versatility
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Can be portable OR permanent
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Racing-ready out of the box
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Maximum flexibility for different uses/locations
Complete Flexibility - No Bolting
If bolting to ground is not possible there is an extension feet option available. Extension feet can accommodate (user provided) additional weights for improved stability.
The Future of Motion Simulation
ARK PDK represents more than technological advancement - it's the beginning of a new era in motion simulation. By making high-fidelity, wide-bandwidth motion accessible and affordable, we're transforming motion platforms from niche applications to mainstream adoption.
This is the first step in our mission to deliver immersive, practically real-like experiences to everyone. The whole truly is greater than the sum of its parts, and ARK PDK proves that exceptional engineering, innovative thinking, and precise execution can redefine what's possible.
Industry Applications
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Aerospace: High-fidelity flight simulators for pilot training, replicating G-forces and vestibular cues with 1ms latency and FK precision.
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Gaming: Ultra-responsive sim racing and VR platforms with 3G acceleration and haptic feedback, enhancing immersion in esports and casual gaming.
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Healthcare: Motion-based rehabilitation platforms for physical therapy, leveraging FK for biomechanical feedback and AI for personalized treatment protocols.
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Biohacking: Vestibular stimulation and neurofeedback systems for cognitive enhancement, using 400Hz motion and AI-driven analytics.
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Robotics: Real-time kinematic control for autonomous manipulators, supported by FK sensing and SDK integration.
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XR/AR/VR: Low-latency motion tracking for immersive virtual environments, compatible with major headsets and game engines.
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Simulation: Automotive ADAS testing, marine vehicle simulation, and medical training platforms with micro-accurate kinematics.