# Models Documentation This folder contains the complete 3D CAD model previews for Team CYBERRCORE's WRO 2026 Future Engineers robot. All mechanical components were custom-designed in-house using **SolidWorks** to achieve a rigid, compact, and competition-ready platform optimized for sensor placement, weight distribution, and drivetrain efficiency. ## 🎯 Mechanical Design Philosophy Our design philosophy is built around **structural rigidity with strategic weight reduction** — a flat-plate chassis architecture that keeps the center of gravity low, simplifies assembly, and provides dedicated mounting zones for every electronic and mechanical subsystem. The X-pattern lightening cutouts in the main body remove material where it is not structurally needed, reducing mass without compromising stiffness.

Full Assembly Isometric View Full Assembly Top View

Left: Full assembly isometric view showing overall vehicle form factor • Right: Top-down view revealing chassis layout, electronics bay, steering geometry, and drivetrain routing

Full Assembly Second Angle

Secondary isometric angle highlighting camera mount, wheel profile, and chassis depth

## ⚙️ Core Mechanical Systems ### 🏗️ Main Chassis

Main Chassis

Primary structural plate featuring X-pattern lightening pockets, integrated standoff posts, and dedicated mounting zones for motor, servo, electronics, and sensor assemblies

**Structural Design Elements:** - **Flat-Plate Architecture**: Single-level structural platform keeping CG as low as possible for stability at speed - **X-Pattern Lightening Cutouts**: Triangular pocket geometry maximizes removed mass while preserving structural load paths - **Integrated Standoff Columns**: Raised posts molded into the chassis for direct PCB and cover mounting without separate hardware - **Dedicated Subsystem Zones**: Distinct areas pre-allocated for motor mount, servo, differential, and sensor brackets — no retrofitting required - **Perimeter Mounting Rail**: Continuous edge flange providing multiple attachment points for external brackets and covers --- ### 🔄 Steering System — 4-Part Ackermann Linkage The front steering system uses a 4-component linkage to achieve Ackermann-compliant geometry, ensuring both front wheels track toward a common turn center during cornering to eliminate tire scrub.

Steer1 — Steering Knuckle Tie Rod
Steer2 — Tie Rod Steering Arm Left
Steer3 — Steering Arm (Left) Steering Arm Right
Steer4 — Steering Arm (Right)

**Component Breakdown:** | Part | Role | Key Feature | |------|------|-------------| | **Steer1** — Steering Knuckle | Connects wheel spindle to chassis upright | L-shaped bracket; upper hole receives servo linkage pin, lower hole bolts to chassis pivot | | **Steer2** — Tie Rod | Transmits servo motion to wheel knuckles | Flat bar with equal-diameter holes at each end for precise, backlash-free length | | **Steer3** — Left Steering Arm | Translates servo rotation to wheel angle | Asymmetric arm with offset boss; asymmetry compensates Ackermann geometry requirement | | **Steer4** — Right Steering Arm | Mirror function of Steer3 for right wheel | Cylindrical boss on the long end for shaft engagement; geometry mirrored to Steer3 | **Ackermann Compliance:** The offset geometry of Steer3/Steer4 ensures the inner wheel turns through a greater angle than the outer wheel during cornering, matching the theoretical Ackermann condition for the vehicle's wheelbase and track width. --- ### 🔧 Rear Drivetrain — Differential & Gear System

Assembled Differential

Assembled differential showing rear shaft, gear stack, and bearing assembly — enables independent rear wheel rotation during turns to prevent inside-wheel scrub

Motor Pinion Gear
0.8M-31T Motor Gear
0.8M-31T Driven Gear
Rear Shaft Assembly

**Drivetrain Specifications:** - **Gear Standard**: 0.8 Module spur gears — compact pitch suited for small-scale precision drivetrains - **Tooth Count**: 31 teeth on both motor pinion and driven gear → **1:1 drive ratio** - **Design Intent**: The 1:1 ratio preserves full motor RPM, prioritizing speed over additional torque reduction; torque is inherently sufficient at this vehicle mass - **Motor Gear** (`08M-31T_Motor`): Small central bore sized to press-fit directly onto motor output shaft - **Driven Gear** (`0.8M-31T`): Large central hub bore for rear shaft engagement, transfers torque into the differential - **Rear Shaft** (`Rear_Shaft`): Through-axle with integrated differential gear stack and bearing seats at both ends; provides the structural spine of the rear drivetrain **Torque and Speed Justification:** | Choice | Reason | Trade-off | | --- | --- | --- | | 1:1 31T-to-31T gear pair | Preserves motor speed for the long straight sections of the WRO track. | Lower torque multiplication than a reduction gear, so the vehicle relies on low mass and smooth acceleration. | | Differential rear axle | Reduces tire scrub during turns and improves repeatability in corners. | Adds more printed parts and assembly alignment checks. | | 0.8 module gears | Strong enough for the vehicle scale while keeping gear diameter compact. | Gear mesh must be printed cleanly and aligned carefully. | | Bearing-supported rotating joints | Reduces friction and improves consistency over repeated laps. | Requires accurate bearing seat tolerances and controlled press-fit. | The drivetrain was selected for controllability rather than maximum acceleration. In WRO Future Engineers, predictable speed and repeatable corner entry are more valuable than a high top speed that causes missed turns or unstable sensor readings. --- ### 🏎️ Wheel & Tire System

Front Wheel
Rear Wheel Tire
Custom Tire (O-ring)

**Wheel Design Differences:** | Aspect | Front Wheel | Rear Wheel | |--------|-------------|------------| | **Hub Type** | Recessed bearing seat (press-fit 3×10×4 bearing) | Direct shaft hub — no separate bearing | | **Spoke Pattern** | 4 cut-out spokes with intermediate web | 4 solid spokes, lighter construction | | **Steering Compatibility** | Rotates freely around fixed spindle via bearing | Fixed to rear axle shaft, driven rotationally | | **Rim Profile** | Wide rim flange for tire retention under steering loads | Standard rim flange | **Tire Design:** - **Form**: O-ring style — a circular torus profile that press-fits over the outer rim flange - **Surface**: Three parallel circumferential grooves on the outer face providing predictable traction and consistent rolling contact patch - **Material**: Flexible rubber/TPU compound allowing elastic stretch during fitting and conforming contact with the track surface - **Advantage**: Simple replacement without tools; consistent geometry batch-to-batch --- ### 📐 Sensor & Electronics Mounts

Camera Mount US-100 Mount
US-100 Ultrasonic Mount

**Camera Mount (`CamMount`):** - Tall vertical bracket providing elevated camera positioning for wider field-of-view coverage of the competition field - Two vertical adjustment slots allow height fine-tuning without reprinting — camera can slide and lock at the optimal angle - Two M3 mounting holes at the base for rigid chassis attachment - Angled forward lean designed to aim the camera slightly downward for near-field obstacle detection **US-100 Ultrasonic Mount (`US100_Mount`):** - Box-form bracket with square central cutout sized precisely to the US-100 sensor body - Side snap/clip tab retains the sensor without additional fasteners for quick swap during competition - Four corner mounting holes for secure chassis attachment - Compact profile minimizes aerodynamic interference and weight at the front/rear of the vehicle --- ### 🔩 Motor Mount

Motor Mount

U-bracket motor mount with snap-fit clamp for DC motor body and two M3 bolt holes for chassis attachment

- **U-Bracket Form**: Wraps around the motor body providing support on three sides against vibration and torque reaction - **Snap Clip**: One side features a flexible retention tab that snaps over the motor body for tool-free field replacement - **Dual Mounting Holes**: Two M3 holes on the base flange provide rigid, over-constrained attachment to the chassis to prevent any rocking under drive load - **Gear Alignment**: Mount geometry positions the motor output shaft at the exact center distance required for 0.8M gear mesh with zero adjustment needed --- ### 🛞 Front Wheel Mount

Front Wheel Mount

Front wheel upright with square steering pin slot, bearing bore, and dual attachment holes connecting the steering linkage to the wheel spindle

- **Square Slot**: Receives the servo/steering pin ensuring zero rotational slip between steering command and wheel response - **Bearing Bore**: Precision-sized pocket for 3×10×4 bearing press-fit, providing a smooth low-friction pivot axis for the front wheel - **Dual Hole Attachment**: Two mounting points prevent single-point failure and provide the moment arm needed to resist steering loads --- ## 🔩 Hardware Components

3x10x4 Bearing
3×10×4 Bearing
Spacer (Thin) Thick Spacer
Spacer (Thick)
M3 Washer

| Component | Specification | Purpose | |-----------|---------------|---------| | **3×10×4 Bearing** | ID: 3mm, OD: 10mm, Width: 4mm | Front wheel spindle rotation; rear shaft support; eliminates friction at high-load rotating joints | | **Spacer (Thin)** | Hollow cylinder, small length | Axial positioning of gears and wheels on shaft; prevents lateral play without adding excess mass | | **Spacer (Thick)** | Hollow cylinder, greater length | Wider axial gaps between components; used where gear or bearing stack-up requires longer standoff | | **M3 Washer** | M3 standard flat washer | Load distribution under bolt heads and nuts; prevents fastener pull-through in printed parts | --- ## 📁 3D Model File Index All models were designed in **SolidWorks** and are documented here as PNG render previews. The table below lists every custom-printed or custom-modeled component in the vehicle assembly. *Quantities listed are for one complete vehicle* | Component | Preview | Qty | Description | |-----------|---------|-----|-------------| | **Main Chassis** |

| TBD | Standard flat washer for M3 fasteners | --- ## 🏭 Design & Manufacturing ### 🖥️ CAD Platform All components were modeled in **SolidWorks** with full parametric feature trees, enabling rapid design iteration and precise dimension control. Assembly files validate fit, clearance, and motion range before any part is printed. ### 🖨️ Printer Platform All parts were printed on a **Bambu Lab A1 Mini** using **Bambu Studio** as the slicer. The A1 Mini's automatic flow calibration, multi-axis vibration compensation, and fast print speeds (up to 500 mm/s travel) made it possible to iterate quickly between design revisions during development. Dimensional accuracy is high out of the box, which is critical for bearing press-fit seats and gear mesh tolerances. | Setting | Value | | --- | --- | | Printer | Bambu Lab A1 Mini | | Slicer | Bambu Studio | | Nozzle diameter | 0.4 mm (standard); 0.25 mm for fine gear details if available | | Bed surface | Textured PEI plate | | Print speed | 150–250 mm/s for structural parts; 20–25 mm/s for TPU tires | | Flow calibration | Auto-calibration run before each material change | ### 🖨️ 3D Printing Strategy - **Target Material**: PLA for initial prototyping; ABS or PETG for competition parts requiring impact resistance and thermal stability - **Gear Infill**: 100% for all gear components to prevent tooth deformation under repeated meshing load - **Structural Parts**: 40–60% infill with rectilinear or gyroid pattern for chassis, mounts, and brackets - **Bearing Seats**: Printed at 0.08–0.1mm layer height for dimensional accuracy required for press-fit bearing installation - **Orientation**: Parts oriented to place layer lines perpendicular to primary stress direction, maximizing inter-layer tensile strength where needed ### 🧪 Material Selection per Component #### Material Overview | Material | Strengths | Weaknesses | Used for | | --- | --- | --- | --- | | **PLA** | High dimensional accuracy, stiff, easy to print, gear-friendly surface | Brittle under impact, low heat resistance (~60 °C), not ideal for repeated flex loads | Gears, wheels, low-stress mounts | | **PETG** | Impact resistant, tough, good layer adhesion, heat resistant (~80 °C), slight flex prevents crack propagation | Slightly lower stiffness than PLA, strings more during printing, bearing seats need careful calibration | Chassis, steering linkage, motor mount, axle | | **TPU (95A)** | Flexible, elastic, excellent grip and traction, absorbs vibration | Difficult to print fast, cannot be used for rigid structural parts | Tires only | #### Per-Component Material Decisions | Component | Material | Infill | Layer Height | Orientation | Reason | | --- | --- | --- | --- | --- | --- | | **Main Chassis** | PETG | 50% Gyroid | 0.15 mm | Flat (XY) | Main structural load path; PETG handles corner impacts and motor vibration without brittle fracture | | **Motor Mount** | PETG | 60% Rectilinear | 0.15 mm | Upright | Holds motor under continuous torque reaction and vibration; PETG's toughness prevents snap at bolt holes | | **Front Wheel Mount (×2)** | PETG | 55% Gyroid | 0.10 mm | Upright | Bearing press-fit seat demands tight dimensional tolerance; PETG's toughness handles steering side loads | | **Steer1 — Knuckle (×2)** | PETG | 55% Rectilinear | 0.15 mm | Flat | Repeated bending stress from steering inputs; PETG prevents crack propagation at the L-bend | | **Steer2 — Tie Rod** | PETG | 50% Rectilinear | 0.15 mm | Horizontal | Under axial tension and compression every steering cycle; PETG is tougher than PLA for slender rod geometry | | **Steer3 — Left Arm** | PETG | 55% Rectilinear | 0.15 mm | Flat | Asymmetric arm loaded sideways; PETG tolerates the offset bending moment better than PLA | | **Steer4 — Right Arm** | PETG | 55% Rectilinear | 0.15 mm | Flat | Same reasoning as Steer3 | | **0.8M-31T Motor Gear** | PLA | 100% Rectilinear | 0.08 mm | Flat (teeth upright) | Gears need stiff, hard tooth surfaces; PLA provides better mesh accuracy and surface hardness than PETG at this scale | | **0.8M-31T Driven Gear** | PLA | 100% Rectilinear | 0.08 mm | Flat (teeth upright) | Same as motor gear; 100% infill prevents tooth deformation under repeated meshing load | | **Rear Shaft** | PETG | 80% Rectilinear | 0.12 mm | Horizontal along shaft axis | Primary drivetrain axle under torsion and bending; PETG's toughness handles shock loads at gear mesh point | | **Front Wheel (×2)** | PLA | 40% Gyroid | 0.15 mm | Flat | Low mechanical stress — only rotates on bearing; PLA gives good dimensional accuracy for bearing seat | | **Rear Wheel (×2)** | PLA | 40% Gyroid | 0.15 mm | Flat | Fixed to axle, no bearing; low stress; PLA's stiffness is sufficient | | **Tire (×4)** | TPU 95A | 100% | 0.20 mm | Flat | Must stretch over rim and provide grip; only flexible material suitable for O-ring tire profile | | **Camera Mount** | PLA | 35% Gyroid | 0.15 mm | Upright | No significant mechanical load; PLA's rigidity keeps camera angle stable; lighter than PETG | | **US-100 Mount** | PLA | 35% Gyroid | 0.15 mm | Flat | Sensor holder only — no dynamic load; PLA is sufficient and prints cleanly for snap-clip detail | | **Spacers (Thin / Thick)** | PLA | 100% | 0.10 mm | Upright | Axial positioning parts; need accurate length; 100% infill prevents compression creep | | **M3 Washer** | PLA | 100% | 0.10 mm | Flat | Load distribution only; if standard metal washers are available, prefer those | #### Key Printing Notes - **Bearing seats** (Front Wheel Mount, Front Wheel, Rear Shaft): print at 0.08–0.10 mm layer height and calibrate flow rate before production runs. A 0.1 mm undersized bore is easier to open than reprinting an oversized one. - **Gears**: orient so tooth layer lines run perpendicular to the tooth face (teeth pointing up/flat print). Use a 0.4 mm nozzle minimum; 0.25 mm nozzle preferred for 0.8M tooth detail. - **TPU tires**: print slow (20–25 mm/s), disable retraction or use minimal retraction, and set 100% infill for consistent hardness around the circumference. - **PETG warp**: use a PEI or glass bed at 70–80 °C; avoid cooling fan for first 2–3 layers. Use brim for thin upright parts (Steer arms, Motor Mount). - **Symmetric parts** (Steer3/Steer4, Front Wheel Mounts): print left and right in the same batch on the same orientation to ensure geometric symmetry. ### 🔄 Design Iteration Process 1. **Conceptual Layout** — Component placement defined in assembly sketch to lock wheelbase, track width, and sensor positions 2. **Individual Part Modeling** — Each component modeled parametrically with design intent captured in feature names and equations 3. **Assembly Validation** — Full assembly checked for interference, range-of-motion clearances, and cable routing paths 4. **Prototype & Test** — First-print fit check, steering geometry validation, and drivetrain engagement verification 5. **Refinement** — Dimensional corrections, wall thickness optimization, and fastener clearance adjustments applied before production prints ## ✅ Mechanical Validation Tests | Test | Procedure | Acceptance criteria | | --- | --- | --- | | Steering range | Move servo from minimum to maximum command while wheels are lifted. | Linkage reaches both steering directions without binding or wheel/chassis contact. | | Ackermann behavior | Observe inner/outer wheel angles during left and right steering. | Inner wheel turns more sharply than the outer wheel in both directions. | | Gear mesh | Spin the drivetrain by hand and then under low PWM. | No skipping, tight spots, or visible gear wobble. | | Differential action | Hold one rear wheel and rotate the opposite wheel gently. | Differential allows relative wheel motion without excessive friction. | | Bearing fit | Press bearings into front wheel mounts and rotate wheels. | Bearing stays seated and wheel rotates freely. | | Sensor mount rigidity | Shake chassis lightly and inspect camera/US-100 brackets. | Sensor angle does not shift under normal handling. | | Track clearance | Roll vehicle through a practice corner and over cable routing. | Chassis, wires, and mounts do not scrape or catch. | ## ⚠️ Mechanical Risks and Mitigations | Risk | Mitigation | | --- | --- | | Servo linkage backlash | Use short linkage parts, tight fasteners, and repeat `servo_tune.py` after assembly. | | Gear misalignment | Motor mount fixes shaft center distance and assembly is checked before autonomous runs. | | Camera vibration | Tall camera mount is bolted directly to the chassis and checked before obstacle testing. | | Printed part warping | Competition parts should be printed with controlled orientation and higher infill where loads are concentrated. | | Tire slip | O-ring tires provide a simple repeatable contact patch and can be replaced quickly if worn. | | Battery/electronics weight shift | Chassis has dedicated electronics zones so mass stays low and centered. | ## 🔁 Repeatability Notes - Keep the same print orientation for left/right steering parts so geometry stays symmetric. - Ream or lightly clean bearing holes only when needed; oversized seats reduce repeatability. - Mark final servo horn position after tuning so the steering center can be rebuilt after maintenance. - Use the same wheel/tire batch during timed tests to avoid traction differences. - Route sensor cables away from moving steering links and gears before every run. --- ## 🧩 Assembly Guide ### Phase 1: Rear Drivetrain 1. Press 3×10×4 bearings into rear shaft bearing seats 2. Slide driven gear (`0.8M-31T`) onto rear shaft and secure axially with thin spacers 3. Mount motor onto `motorMount` bracket; press motor gear (`08M-31T_Motor`) onto motor output shaft 4. Bolt `motorMount` assembly to chassis — verify gear mesh engagement and backlash 5. Install rear wheels onto shaft ends, securing with washers and locking fasteners ### Phase 2: Front Steering System 1. Press 3×10×4 bearings into `Front_Wheel_Mount` bearing bores 2. Install `Steer1` knuckles into chassis front pivot points 3. Connect `Steer3` and `Steer4` arms to servo output horn and knuckle pins respectively 4. Thread `Steer2` tie rod between knuckle connection points; adjust length for zero toe-in at center 5. Install front wheels onto spindles through bearing bores; verify free rotation with no lateral play ### Phase 3: Sensor & Electronics Integration 1. Bolt `CamMount` to designated chassis standoff holes; slide camera module into slots, set height, tighten 2. Snap US-100 sensor into `US100_Mount` bracket; bolt bracket to front chassis face 3. Install PCB/controller into electronics bay using chassis integrated standoffs 4. Route all wiring through chassis cable channels away from moving drivetrain components --- ## ✅ Validation Checklist - **Steering Range**: Confirm full left-to-right servo travel translates to expected wheel deflection angles without binding - **Differential Function**: With rear wheels off ground, verify each rear wheel can rotate independently while the other is held - **Gear Mesh**: No noise or skip at full motor speed; correct backlash (0.1–0.2mm) between 0.8M gears - **Bearing Seating**: All bearings fully seated, no axial float, smooth rotation under light finger pressure - **Sensor Alignment**: Camera FOV centered on track ahead; US-100 sensors aimed level and perpendicular to travel direction - **Fastener Torque**: All M3 bolts confirmed snug; locking elements (nyloc or threadlocker) applied to high-vibration joints --- For electrical systems documentation: [Schemes Documentation](../schemes/README.md) For software implementation and algorithms: [Software Documentation](../src/README.md) For performance demonstrations: [Video Documentation](../video/README.md) For additional resources and photos: [Other Documentation](../other/README.md)