Post by Honus on Sept 22, 2014 7:06:54 GMT
Here's an animatronic cannon system I made for my friend Carl's Predator cannon and backpack. The system is operated using push buttons in the gloves and when a button is pushed the cannon moves through a programmed sequence, complete with light up cannon barrel and sound effects.
Here's a video of the cannon in action-
I began by making the mount for the servo that would sit inside the cannon and allow it to rotate right and left. I made the base plate from 1/8" thick Aluminum sheet and mounted the HS-485HB servo using 4 Aluminum standoffs. I drilled a hole in the base plate that would allow the 1/2" diameter servo extension to stick through and then I supported the extension using a 1/2" bore bearing mount. This bearing mount would take any large side loads off the servo. I also cut a slotted hole so the servo lead wires could stick through the base plate.
I decided to make the cannon arm from a single piece of Aluminum. I happened to have a big 1" thick Aluminum plate section on hand so I cut a large bar from it using my portable band saw. I drew lines on the Aluminum and rough cut out the notched ends and a "U" shaped pocket for the upper pivot servo (Hitec 645MG) and then finish cut them using my lathe. I located the pivot holes on each end of the arm and drilled them using a 1/4" drill with my drill press. Then I notched the side of the arm where the servo arm would be positioned and mounted the servo using four socket head screws. I had to mill out a small pocket on the underside of the arm so the servo lead would clear. I then cut a relief in the top of the arm so I could attach the resin detail plate from Carl's resin cast cannon arm.
Finally I made the main pivot bracket. This was made from a 1/2" thick piece of Aluminum plate rough cut with the bandsaw and then milled using the lathe. There is a 3/8" diameter hole near the top of the bracket and a bronze bushing was pressed into the hole- the bronze bushing supports the 1/4" diameter stainless pivot rod. The main pivot bracket has another HS-645MG servo mounted to it. The servo has a 12T gear mounted to it that drives a 48T gear that is bolted to the cannon arm. The 1/4" stainless pivot rod is fitted through the hole in the left side and then slid through the bronze bushing and the hole in the right side of the cannon arm and is press fit into the hole in the 48T gear. A small Aluminum plate was then bolted to the bottom of the main pivot bracket- the entire assembly was then ready to be fit to the backpack.
Now that I had the mechanics done I needed to make it move. I used an Arduino Pro Mini to handle the inputs and servo movements and and an Arduino Pro with an Adafruit Wave Shield to handle the sound effects. There is a small board that has three transistors on it- the transistors turn on the helmet laser sight and trigger the cannon LED and sound effect. The board also has a 3.3V regulator to provide power for the helmet laser sight.
The cannon LED is a bright blue Luxeon that is driven by a constant current "Buck Toot" driver. In order to avoid any servo noise issues the Arduinos are powered by a 9V battery and everything else is powered by four "AA" alkaline batteries. The electronics were mounted to a 1/8" thick Aluminum plate using plastic standoffs and 4-40 screws.
Control inputs would be three small finger tip tactile switches. The switches are on/off so if pushed a sound would repeat itself over and over until it was turned off. Likewise the cannon would continue to move through it's programmed sequence until it was turned off. The finger tip switches were connected to the backpack using an ethernet cable that would be run down the arm and the switches would sit inside the glove fingers.
Here's a video of the cannon in action-
I began by making the mount for the servo that would sit inside the cannon and allow it to rotate right and left. I made the base plate from 1/8" thick Aluminum sheet and mounted the HS-485HB servo using 4 Aluminum standoffs. I drilled a hole in the base plate that would allow the 1/2" diameter servo extension to stick through and then I supported the extension using a 1/2" bore bearing mount. This bearing mount would take any large side loads off the servo. I also cut a slotted hole so the servo lead wires could stick through the base plate.
I decided to make the cannon arm from a single piece of Aluminum. I happened to have a big 1" thick Aluminum plate section on hand so I cut a large bar from it using my portable band saw. I drew lines on the Aluminum and rough cut out the notched ends and a "U" shaped pocket for the upper pivot servo (Hitec 645MG) and then finish cut them using my lathe. I located the pivot holes on each end of the arm and drilled them using a 1/4" drill with my drill press. Then I notched the side of the arm where the servo arm would be positioned and mounted the servo using four socket head screws. I had to mill out a small pocket on the underside of the arm so the servo lead would clear. I then cut a relief in the top of the arm so I could attach the resin detail plate from Carl's resin cast cannon arm.
Finally I made the main pivot bracket. This was made from a 1/2" thick piece of Aluminum plate rough cut with the bandsaw and then milled using the lathe. There is a 3/8" diameter hole near the top of the bracket and a bronze bushing was pressed into the hole- the bronze bushing supports the 1/4" diameter stainless pivot rod. The main pivot bracket has another HS-645MG servo mounted to it. The servo has a 12T gear mounted to it that drives a 48T gear that is bolted to the cannon arm. The 1/4" stainless pivot rod is fitted through the hole in the left side and then slid through the bronze bushing and the hole in the right side of the cannon arm and is press fit into the hole in the 48T gear. A small Aluminum plate was then bolted to the bottom of the main pivot bracket- the entire assembly was then ready to be fit to the backpack.
Now that I had the mechanics done I needed to make it move. I used an Arduino Pro Mini to handle the inputs and servo movements and and an Arduino Pro with an Adafruit Wave Shield to handle the sound effects. There is a small board that has three transistors on it- the transistors turn on the helmet laser sight and trigger the cannon LED and sound effect. The board also has a 3.3V regulator to provide power for the helmet laser sight.
The cannon LED is a bright blue Luxeon that is driven by a constant current "Buck Toot" driver. In order to avoid any servo noise issues the Arduinos are powered by a 9V battery and everything else is powered by four "AA" alkaline batteries. The electronics were mounted to a 1/8" thick Aluminum plate using plastic standoffs and 4-40 screws.
Control inputs would be three small finger tip tactile switches. The switches are on/off so if pushed a sound would repeat itself over and over until it was turned off. Likewise the cannon would continue to move through it's programmed sequence until it was turned off. The finger tip switches were connected to the backpack using an ethernet cable that would be run down the arm and the switches would sit inside the glove fingers.
