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Step 2Design and layout
I wanted my animatronic head to move up/down, turn right/left, rotate and have eyes that light up. What is really important is to keep everything as light weight as possible to avoid overloading the servos. The finished Horus helmet will be constructed entirely from blue foam and cardboard to save weight (and cost!)
I used standard sized servos: two Hitec HS300 servos for the rotation and turning movements and a HS605BB servo to move the head up and down. THe 605BB servo has twice the load rating of the HS 300 servo- it needs to be stronger because it's moving the entire weight of the head.
The first thing is to figure out the movements and range of motion. Working from a base plate, I figured I'd need one hinge for my up/down movement, one hinge for my turn right/left movement and a pivot for my rotational movement. I also wanted my head movements to be grouped together so as the head turned it would rotate and as it moved up and down the eyes would light up. By grouping functions together I would be able to control everything with only two flex sensors.
There are also two sets of "fans" located on the sides of the helmet. I wanted these to be linked to the up/down head movement- the servos for these aren't shown on the finished animatronic armature as they will be added when the foam helmet is constructed. I do show them on the diagrams and will demonstrate how to reverse the rotation of one of the servos- this is necessary to get the fans on opposite sides of the helmet to rotate in the same direction at the same time.
How it works:
Using the POLY function/FOLLOWER mode, the controller takes the analog input from the flex sensor and assigns it a value between 0 and 1023 based on input voltage corresponding to 0 to 3.3v. The servo outputs ( labeled 0 and 2) are PWMs (pulse width modulation) that reflect the assigned values, so when the input voltage is 0v the servo is at one end of its travel and when the input voltage is 3.3v the servo will move to the opposite end of its travel, tracking the bend in the flex sensor. The digital outs on the board also reflect this so you can also control the speed of a motor or brightness of a lamp. At the time of this writing, the firmware for the controller only allows the servos to rotate 90 degrees (most standard servos can rotate 130 degrees.) I've read on the MakingThings forum that full 130 degree rotation could be included in a future firmware update.
Note that the final configuration of the battery and controller mounting will be slightly different than what I have done on my test rig.
I used standard sized servos: two Hitec HS300 servos for the rotation and turning movements and a HS605BB servo to move the head up and down. THe 605BB servo has twice the load rating of the HS 300 servo- it needs to be stronger because it's moving the entire weight of the head.
The first thing is to figure out the movements and range of motion. Working from a base plate, I figured I'd need one hinge for my up/down movement, one hinge for my turn right/left movement and a pivot for my rotational movement. I also wanted my head movements to be grouped together so as the head turned it would rotate and as it moved up and down the eyes would light up. By grouping functions together I would be able to control everything with only two flex sensors.
There are also two sets of "fans" located on the sides of the helmet. I wanted these to be linked to the up/down head movement- the servos for these aren't shown on the finished animatronic armature as they will be added when the foam helmet is constructed. I do show them on the diagrams and will demonstrate how to reverse the rotation of one of the servos- this is necessary to get the fans on opposite sides of the helmet to rotate in the same direction at the same time.
How it works:
Using the POLY function/FOLLOWER mode, the controller takes the analog input from the flex sensor and assigns it a value between 0 and 1023 based on input voltage corresponding to 0 to 3.3v. The servo outputs ( labeled 0 and 2) are PWMs (pulse width modulation) that reflect the assigned values, so when the input voltage is 0v the servo is at one end of its travel and when the input voltage is 3.3v the servo will move to the opposite end of its travel, tracking the bend in the flex sensor. The digital outs on the board also reflect this so you can also control the speed of a motor or brightness of a lamp. At the time of this writing, the firmware for the controller only allows the servos to rotate 90 degrees (most standard servos can rotate 130 degrees.) I've read on the MakingThings forum that full 130 degree rotation could be included in a future firmware update.
Note that the final configuration of the battery and controller mounting will be slightly different than what I have done on my test rig.
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