Full Sculpture

Requirements

Integration & User Interface

Mini Sculpture Components

Elevator Chains

Extending Ramp Mechanism

Swinging Arm

Code Flowchart

WM2D Simulations

Requirements

Automatic control
Operates without marbles falling from the sculpture and where marbles eventually return to the top of the structure.
Include Mini Kinetic Sculpture as part of the Full Kinetic Sculpture.
Have to at least one sensor and one servomotor
The sensor should be used as a measurement of either ball position, ball velocity, ball count, ball color or anything else that is able to measure a physical property of one of the rolling/moving objects
The servomotor should be controlled automatically by the measurements of the sensor and used to move a specific part of the Full Kinetic Sculpture
One human interface to interrupt the automatic operation of the active and automatic Full Kinetic Sculpture.
Limit the use of duct tape, cardboard or other temporary measures. Original prototype parts can be CAD/CAM parts created by a LaserCAMM or a 3D printer

Integration & User Interface

Our "tilting basket", and "extending ramp" designs were all used in our full sculpture.

A rotating "elevator" chain is incorporated in our sculpture to bring a marble at the end of its track back up to the top, without any user input to do so.

Our user interface is a button that can be pushed, determining the starting point of the marble. This impacts our sculpture as the "extending ramp" portion of our sculpture will extend different amounts depending on where the marble is dropped from. However, if the button is not pushed, a marble will still fall down the ramp in order for the sculpture to remain fully autonomous.

Mini Sculpture Components

The full sculpture must include and integrate your mini sculpture design concept(s). Show how this has been done and how possible several concepts are integrated:

The designs in our mini sculpture that were used in our full sculpture included the "opening system", "tilting basket", and "extending ramp".

Elevator Chains

A rotating "elevator" chain is incorporated in our sculpture to bring a marble at the end of its track back up to the top, without any user input to do so. This is one of the key components of making our sculpture fully autonomous as it gives the marble potential energy again once it is out of kinetic energy.

User Interface

What does your User Interface look like and how does interaction with the user interface change/influence the operation of your full sculpture?:

Final Results

Extended ramp

Swinging Arm

Tilting basket

Extending Ramp Mechanism

The extending ramp used an offset crank mechanism to quickly extend and retract the ramp (the motor only has to move a half revolution to go from fully extended to fully retracted or vice-versa). The angle needed to extend the ramp a certain amount is approximated using an inverse logistic function.

The needed extension distance to make the ball always land in a fixed basket is given by

x_0 = x(t) - v_x*sqrt(2y/g)

where x_0 is the extension distance, x(t) is the horizontal distance from the end of the fully retracted ramp to the basket, v_x is the ball velocity, y is the vertical distance from the ramp to the basket, and g is acceleration due to gravity. When implementing this in code, a constant amount (1.5 m/s) was also subtracted from the ball's velocity to account for frictional losses between the speed sensor and end of track.

Swinging Arm

A problem faced with the swinging arm was that the torque produced by its weight would tend to make the arm sag when the motors were off. To correct this, we coded the motor to continuously detect this sagging and run the motor to correct it.

Code Flowchart

We used the multitasking function of the NXT to run all three automated components separately and to simplify the coding process

WM2D Simulations

Extending Ramp

Swinging Arm

Tilting Basket

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