Otto Ninja for original NanoV3 plus Shield

prusaprinters

Being a walking and wheeled robot, the Ninja looks really interesting to build. However, it is difficult to get the smaller Nano PCB, plus it is quite expensive compared to the Nano V3 plus Shield. (I have not yet experimented with the ESP boards) Many builders may have several of the older Nano systems and so this remix allows creation of the Ninja starter model using a) the 16340 power board and b) the NanoV3 plus Shield. I completed some basic programming to show the movement of Ninja:   https://youtube.com/shorts/zjgVOHkwsz4A bit of philosophy:  Often we build these projects and just insert code someone else wrote and hope the project works. This is not the nature of computer controlled projects. The software is as important, if not more important than the hardware. I've include a zip file that contains my code to make Ninja walk and roll. I encourage all builders to really digest the instructional explanation (in the PDF included with the zip) to modify the constant for their own servos and eventually add their own movements. The Ninja is significantly more complicated than the basic Otto and if you find this daunting, start with that model.I've included a PDF that shows all the parts I ordered from AliExpress. Update #3: Aug16, '23: Added code and detailed explanation for calibrating and getting Ninja to do basic movements.Update #2: July 21, '23: Remixed the feet to add a 2nd O-Ring for grip when walking.Update #1: July 19, '23:  Complete Ninja has been built with Nano v3 & shield and 16340 power board. Body: The body is 6mm taller. It was just not possible to fit everything into the original size. However, this should not affect attachment with other parts or operation. (Balance might change slightly since all the inside parts are different). The 16340 power board and upper shield can be screwed down with a 4-6mm M2 screw. I only use a single screw to secure each board.  You can use a KCD11 (10x15mm) rocker switch for power or a toggle switch. The body has a cylinder to hold the buzzer.The Shield Mod: I modified my nano shield and removed the “Japan Jack”. It should not be used as you can damage the linear regulator on the Nano V3. I simply used side cutters to break away the plastic shell, then heated the bottom board side of the 3 connectors and pulled from the top side to remove each pin. You can also cut the pins on the top to isolate them before attempting to remove. This made installing the shield board much easier as I didn't need a large cutout for that connector.Legs: I used the OTTO NINJA MODIFIED LEGS (Alex Just Alex). These fit much better with the MG90s servos I purchased.Foot: I've modified each foot to add an O-Ring to the bottom to provide grip as Ninja rotates when walking. All 4 O-rings are the same size and should be:  VMQ Silicon O-Rings with 62mm OD and CS:4mm. Stretch one to fit on the outer ring. Once stretched an O-Ring can't be used on the bottom. I bought a package of 10 for under $5 USD. I found Silicon were softer than rubber ones I found. (Print this part @0.1mm layer height).Sonar Senor: By mistake, I ordered a few of the SRF05 sonar sensors and so I included a plate for this. You can use the SRF05 just like the 04. Just connect 4 pins as on the 04 and leave the 5th pin unconnected. Note the plate is intended to fit very tightly to hold the sensor in place. You will need to bend the pins (if necessary) so they are at right angles to the body. I used tweezers to place all pins in the handle and bent them all at once as shown in the included picture.Buzzer: I used an active Buzzer. The Dupont connectors ends are brutally long and would not fit into the small space allocated for the buzzer on the bottom of the body. I cut the ends off 2 x Dupont wires and soldered  the bare wire ends to the Buzzer pins and then bent them slightly to allow insertion into the body cylinder holder. I used heat shrink tubing over the joints, but it is not necessary. You can see my buzzer and connector in the pictures above.LED Matrix: I used the Open-Smart 16x8 I2C LED Matrix (AliExpress). I adjusted the original holder slightly so it would hold this module very snug. When using this I2C module, connect SDA to A4 and SCL to A5. Then use the blockly code for “Eyes Pins I2C” to identify the hardware connection. After, simply use Blocks to modify the display. (I set display brightness to 0 to save battery).Battery Power: The original Ninja uses a 9v battery that is comprised of a single (small) 3.7 cell that is boosted to 9v and then must be stepped-down to 5v using the regulator on the NanoV3 or a small external regulator. If you feed 9v to the Vin pin and use the NanoV3 regulator, which is a linear regulator,  it is possible, if a servo binds, to pull more than 1A from the regulator (if your 9v battery will source that much), which can damage the Nano regulator (you are pulling 5W from a regulator with no heatsink, designed for about 1W). I designed this head to use the 16340 power board that boosts a single 3.7 Li cell to 5v and feeds it directly into the +5v and Gnd. (I feel this will have more capacity than the 9v lithium).  I used a 2 pin JST XH connector with 2 wires attached and soldered the wires to the power board and then used the connector to attach to any +5v and Gnd stakes that are convenient. This board is available from a number of AliExpress sources and DIYMORE.CC. (diymore Official Store on AliEx.). Search for "16340 lithium battery module". Try to get a good quality 16340 battery (button type). Head Lid and button: The buttons that were available from AliExpress did not fit the existing Head Lid. I remixed the lid to accept the buttons that you'll see in the parts list. I also secured the button PCB with 2 x M2 screws. You can use an M2 machine screw or the large screws that come with servos.Print Instructions: I used 0.3 layer height for most things. I used 0.2 for the Legs holder. For the Foot, I used 0.1mm layer height because of the detail holding the bottom ORing. I used 3-4 perimeters so the walls were solid. I used PETG for the legs holder & feet. This allows the legs to  snap into the body a little more reliably and the foot can hold the bottom ORing. (PETG is more pliable than PLA). But you can print everything with PLA. No supports were necessary for any parts here.The body and lid are printed with the “fuzzy skin” option in PrusaSlicer to hide layer lines, and the ghosting from the inner wall supports that occur because the walls are only 1.5mm thick. This turned out very well.Step files are included in the ZIP file attached.