Mechanical & CAD · 2026-09-02
Automated Stair-Climbing Wheelchair FYP: Mechanical Design and CAD Guide.
A comprehensive engineering breakdown of kinematic mechanism selection, center of gravity stabilization, high-torque drivetrain calculations, and SolidWorks 3D CAD modeling.
The automated stair climbing wheelchair fyp represents one of the most prestigious and challenging biomedical-mechatronics capstone projects in Pakistan. Utilizing industry-grade cad design services pakistan to model kinematic mechanical design, high-torque power transmission, dynamic balance control, and patient safety protocols, this project addresses a critical accessibility challenge in Pakistan's multi-story infrastructure.
1. Mechanism Architecture: Tri-Star Cluster vs. Tracked Drive
When modeling the stair-climbing base in SolidWorks, teams generally choose between two primary mechanical topologies:
- Tri-Star (Planetary Three-Wheel) Mechanism: Three smaller wheels arranged in an equilateral triangular bracket rotating around a central hub axle. On flat ground, the lower two wheels roll normally; when confronting a stair riser, the central axle rotates, stepping the top wheel over the stair edge.
- Continuous Rubber Track Mechanism: Dual high-friction rubber tracks deployed via high-torque linear actuators when climbing mode is engaged, distributing contact pressure evenly across multiple stair edges.
2. Active Gyroscopic Self-Leveling Seat Design
Safety is the primary grading criterion for biomedical FYPs. As the wheelchair chassis tilts to 30-35 degrees while ascending stairs, the patient seat must rotate in reverse to maintain an absolute level horizontal orientation (plus/minus 1.5 degrees). This is achieved via:
- A rigid pivot axle mounted directly above the wheelchair center of mass.
- A precision lead-screw or high-thrust electric linear actuator connected between chassis and seat frame.
- An MPU-6050 or BNO055 orientation sensor feeding real-time pitch feedback to an embedded PID microcontroller loop.
3. Drivetrain Calculation and Braking Safety
The drivetrain must utilize self-locking worm gearboxes or electromagnetic fail-safe brakes. If power is accidentally disconnected mid-stair, the wheelchair must physically lock in position and prevent catastrophic back-driving down the stairwell.
Frequently Asked Questions
Which mechanism is better for stair climbing: Tri-Star wheels or Continuous Rubber Tracks?
Tri-star planetary wheel clusters are superior for standard stair geometries with moderate weight and low friction, while continuous rubber tracks offer superior grip on irregular outdoor steps but require heavier chassis construction and higher motor torque.
How do you maintain user balance and prevent tipping on stairs?
Incorporate an active self-leveling seat mechanism actuated by a linear actuator or ball screw driven by a closed-loop IMU sensor that automatically adjusts seat angle to remain horizontal regardless of stair slope.
What motor torque is required to lift a 70kg payload up stairs?
Factoring in a 30-degree standard stair inclination and mechanism radius, dual 24V high-torque worm-gear DC motors (minimum 15-25 Nm output torque each at 30-40 RPM) are necessary, paired with heavy-duty high-amp motor drivers.
Educational engineering guide published by PakMEC Prototyping Division. Contact our engineers for custom circuit design, machining, and technical prototype fabrication.
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