V. (Intermediate) Active suspension

V. (Intermediate) Active suspension

Objectives

• Isolate any bogie-induced vibrations
• Have cabin stay parallel with ground during elevation shift
• Ensure parallelness with ground even with passenger load-up at station
• Must have sensors active monitoring the motion/track of system + control system to interpret current state and make adjustments
• Must be compact/easily conceable

Design Requirements and Specifications

    - Satisfy following requirements

i. The cabin must be must maintain a horizontal angle (parallel with respect to ground).

ii.The suspension system should constrain the movement of the cabin such that there are only two degrees of freedom (2 DOF).

iii.A damping system will be needed to isolate the cabin from vibrations and oscillatory motion.

iv.The suspension system must be capable of leveling the cabin to the station platform.

v. The suspension system must interface to both the cabin and the bogie. vi All components and hardware must have a sufficient safety factor associated with the forces and stresses imposed by static and dynamic loading.

Design specifications

• Cabin angle must be able to accommodate 17 degree change in guideway angle
• Cabin motion constrained to 2 DOF
• For ¼ scale suspension design, estimated 650 lbs was accounted for in the weight of the cabin + weight of passengers
• Underdamped solution chosen to allow for more comfortable ride for passengers (With a damping constant value between 0.4-0.8))
• One issue with damping system: when strings compress there will be a misalignment with loading/unloading platforms

i. Solution: Change position of cabin relative to platform without causing further displacement of suspension system

• A modular approach was chosen, where components can be resized.
• “A chain is as strong as it’s weakest link” mentality

State-of-the-Art/Literature Review

• Large BART-like infrastructures are too burdensome for the superway’s goals
• JPODS being considered for use as a solution
• Metropolitan Individual System of Transportation on an Elevated Railway (MISTER) has elevation techniques of up to 45 degrees

Design Concepts and Final Design

• Many designs were considered
• Final design

i. Inner tube connects to cabin and is pulled down due to the mass of the cabin and cargo

ii. Shock pin then pushes down and compresses the shock absorbers against the supports connected to the outer tube

iii. Outer tube is supported by the top connection plate

Analysis

• Equation used to model loading system
• Pressure simulated on tubes
• Shock absorbers utilized in simulation are air shocks

Validation/Testing

• Vibrations tested using a standalone structure
• Accelerometers also used

Money Spent on Project

• Overall cost: $987.75

Results and Discussion

• The vibration isolation unit of the system worked very well
• Actuators could be accurately controlled/adjusted

Conclusions and Suggestions for Future Work

• Not all design requirements could be met

i. Actuators could only support 250 pounds (money constraints)

• Tips for future

i. Look at all ideas

ii. Optimize actuator geometry (make it smaller)

iii. Devices besides actuators should be explored

iv. Keep in contact with other teams