HP Otto: Otto Flip

Otto Flip

Otto flip has a servo controlled arm that uses the power of an elastic band to flip a ball. A continuous rotation servo rotates a cam that tensions the flipper and then releases it.

Additional parts

An HP Otto 'servo wheel' servo for the flipper mechanism. Other brands of continuous rotation servo could be adapted with ph2.0mm connectors.

A selection of elastic bands

Printing

PLA, 15% infill, no supports. All STL files are in the correct orientation for printing.

Assembly

First attach the flipper base to the new Otto top section using 4 screws. 

The flipper mechanism is assembled as shown in the diagram below.

There is an order of assembly which makes the total process easier.

1. Slide the cam adjuster into position 

   

2. Fit the servo horn to the cam and then hold in position while inserting the servo from the other side 

3. 

   Place a lock nut on the bolt and screw in to secure the cam in place, but not so tight that it restricts movement. Use locknut to hold in position 

4. 

   Feed the flipper in from the front, under the cam and secure in place with bolt and locknut - on this bolt the locknut is more effective on the inside edge. Once again the flipper should be able to move freely.

5. The flipper scoop can now be pushed onto the base of the flipper arm.

The anchor for the elastic band is secured to the underside of Otto 

Tension the flipper arm with an elastic band. The tighter the band, the more powerful the flip, but there is an upper limit, beyond which, the servo will be unable to turn the cam.

Electrical Connections

The motor servos are connected to connectors 10 and 11 as usual

I have used connector 4 (pin 26) for the flipper

Code

micropython code to control Otto Flip from the new HP Otto phone app can be found here:  https://github.com/UEA-envsoft/HP-Otto-Otto-Flip

 The joystick control controls movement in any given direction, the D-pad control controls the flipper.