Hey Everyone! I'm back with some more Lego Robotics. This Lego Mindstorms Robot can automatically pan and tilt an iPhone in very small increments to capture amazing time-lapses. I got the idea for this after seeing other time-lapse robots online, but most of them are really expensive. So instead, I decided to build my own using just parts that I already had.
For anyone who is not already familiar with time lapses, time-lapse is a photography technique in which pictures are taken at a set interval. For example, one picture could be taken every ten seconds. When these pictures are played back really quickly (usually 24-30 frames per second), it will look like an extremely sped up video. You could watch the sun move across the sky in a matter of seconds or see the clouds move. Anything that would normally happen very slowly, could be played back very quickly.
I have added a video above of some other time-lapses that I have made without using the pan/tilt robot.
Step 1: What Does It Do?
This robot will very slowly pan and/or tilt the camera as it is capturing the time-lapse. Since it rotates the camera very slowly (less than a degree between photos), when the pictures are played back as a video it will have a very smooth panning movement. You can take a look at my example video to see what this looks like. This robot functions very similar to the time-lapse feature on the commercially available Galileo robot. Before starting the time-lapse, the onscreen controls allow you to set the length of the time-lapse, and how many total degrees it should rotate horizontally and vertically over the course of that time. The robot then automatically calculates the rate in which it should rotate the camera.
The first video I have attached to this step is a demonstration of how the iPhone can be locked into place. The second one shows the effect of rotation on the Time-Lapse
Step 2: Construction- the NXT Brick
The most important part is the NXT brick. The NXT contains the actual computer part of the robot, as well as the memory that stores the programs. The two arrow buttons on the NXT brick are used to adjust the different parameters and settings during setup. The touch sensor I mounted on the side of the NXT brick is used as the 'Enter' button to move on to the next step in setup. For anyone who is not familiar with Lego Mindstorms, there are three ports on the top for connecting servo motors, and four ports on the bottom for connecting sensors.
Step 3: Construction: Horizontal Rotation
The motor that controls the horizontal (left to right) rotation is connected to the turntable by two pinion gears and a worm gear. The resulting gear ratio is a 56:1 ratio, meaning the motor would have to complete 56 full rotations to make the turntable complete one rotation. This is important because the robot must be able to control the turntable very precisely. Since the servos I am using are accurate to one degree, the turntable can be accurately rotated 1/56th of a degree.
Step 4: Construction: Vertical Rotation
The vertical (Up and Down) rotation is controlled very similarly to the horizontal rotation. It also consists of a couple of pinion gears and a worm gear. This servo is connected to the iPhone with a 67:1 gear ratio which allows for even greater accuracy than the horizontal rotation.
Although I have designed the clips to hold an iPhone 4/4s. With some 3D printed parts, you could modify it to perfectly fit almost any smartphone or lightweight camera.
This entire section of the robot is mounted on top of the turntable that I described in the previous step.
Step 5: Software
I programmed the robot using the block based programming software that came with the set. I have attached the program file to this stem as well. To capture the Time-Lapse, I use ProCam from the App Store. It has a mode that will continuously take pictures at any interval. I then use the built-in image capture app on my mac to transfer them from my camera roll to my computer. I use Motion 5 (a program similar to After Effects) to stitch my photos together into a movie. If you don't have Motion or After Effects, there are several free programs that can stitch together Time-Lapses such as Time Lapse Assembler.
Thanks everyone for taking a look at my Instructable. If you have any questions, just leave a comment and I'll be sure to reply. Have fun building!