Elevator Controller
BRANDON AHO AND JINBO ZHU
What are we modeling?
What are our simplifications?

Small model with robotics components

No special operation such as special buttons, weight compensation,
vibrations in the system, safety measures, precise elevation etc.

2 floors

No doors

This is a demonstration of the controller’s basic operation – not a
simulation of an actual elevator.
What are we using to model it?

HCS12 Microcontroller on SSMI Board

Breadboard

Resistors x4

Indicator Switches x2

User Switches x2

DC Stepper Motor

DC Stepper Motor Controller

Actobotics Equipment
What are we using to model it?

HCS12 Microcontroller

Breadboard

Resistors x4

User Switches x2

DC Stepper Motor
Controller
What are we using to model it?

DC Stepper Motor

Indicator Switch x2
(microswitch)

Actobotics equipment
(C channel, sprockets,
chain, various
fasteners, shaft)

2 objects of equal
mass to simulate
elevator and
counterweight
What are we using to model it?
• Normally open contact.
• Normally closed contact.
• Common pin is connected to
HCS12 input pin.
• Grounded via resistor.
• A complete depression of the
lever arm is suggested to
ensure a signal is sent.
How does it all work together?

The microcontroller controls the elevator just how you would expect
it to.

Press a button, no other user buttons will function again until the
elevator reaches its destination.

Controller knows if a floor has been reached through input from one
of two indicator microswitches.
How does it all work together?
Rough Timing Diagram
pseudocode
How the hardware works

Stepper motor has four wires & poles: A, A’, B, B’

Stepper motor controller handles the clockwise/ counter clockwise
rotation of the stepper motor

Pulse the “step” pin to rotate the motor one position. This advances the
DC stepper motor pins in the correct fashion – it is hard-coded onto the
motor controller

Direction pin can be logic 1 or 0.

Motor receives +9V from the AC to DC power source
What special functions of the
HCS12 are we implementing?

Real-Time Interrupt System  Output Compare


Sends a pulse from the HCS12 to the motor controller at varying
intervals, giving us an acceleration profile similar to what one would
expect from a real world elevator.
Loops and logic structures to handle our four states: stationary at
top, stationary at bottom, moving up, and moving down.

As one might expect, the user buttons will not do anything until the
previous button’s corresponding floor has been reached.

The microswitches only cause a state change when the elevator is
already in motion.
Our conclusions

The HCS12 in conjunction with DC stepper motor & controller work
for this small application.

Not enough pins for a full-scale building with potentially more than a
hundred floors.

No accounting for weight changes in the elevator, this factor is
removed by using a stepper motor.

Not as advanced as other elevator controllers which are built with
other features which can control the lighting, doors, sounds, music,
entertainment/news/weather/directory consoles, and even video
communications/ surveillance of modern elevator systems.
Your questions