Language anyone wants to use for numerics. I personally can’t wait for other options. However, the Sphero Mini is new, and it looks like no one has released anythingĮlse. There are other interfaces available for other Sphero robots. My cat has no interest in it, no matter how it is moving around.ġ The interface I’ve been forced to use is the one provided by Unfortunately, the Sphero completely failed at my initial goal. However, it didn’t seem to complement the standard deviation well, only detecting that the robot was stuck in cases where the standard deviation measure already realized it. I’ve tried something that looked at the frequency of the oscillation by looking at the Fourier transform. I’d like to be able to reduce the amount of time the robot takes to realize that it’s stuck. This program manages to bounce around the room pretty well, but it is far from perfect. It can take a while for the robot to realize that it’s stuck, but it reliably will eventually. I found that I could pretty much eliminate the chance of “false positives” - turning around when the robot is not actually stuck. If the standard deviation goes above a certain value for a certain time period, it will turn the robot around.įor being pretty rudimentary, it actually works pretty well. I wrote some code that will continuously monitor the standard deviation. This is a measure of how “spread out” the histogram of the data is. I figured I could capture this behavior by looking at the standard deviation of the rotational velocity. Meanwhile, the stuck version has a much wider distribution of rotational velocities, and is rather bimodal. When the ball is rolling, the rotational velocity is concentrated around zero. If we look at a histogram of that data, as seen in the figure below, the difference is clear. Meanwhile, when moving, the robot’s rotational velocity generally hovers around zero, apart from some brief periods of movement. The robot is constantly rotating in some direction when stuck. Looking at the plot of the rotational velocity of the pitch, as seen in the figure below, we can also see that the frequency of oscillation when stuck is quite high. This was more useful because the amplitude of oscillation was much much greater when stuck than when rolling normally. Instead, I looked at the rotational velocity of the robot - i.e. The robot does the same thing while rolling, rocking back and forth, just not quite as fast and consistently. However, it might be hard to detect that reliably. You can clearly see the oscillation in the plot that you can see in the video. You can see a comparison of the pitch while rolling and while stuck in the figure below. I first looked at the pitch,the angle the robot makes with the horizontal along the direction of its travel. I collected a stream of data from the robot while it was moving normally and while it was stuck. The key thing I noticed was that the robot rocked back and forth when stuck Since I couldn’t find a way to modify the way collisions were detected, I had to come up with a way to do it myself. The robot will hit a wall and just keep going, completely oblivious to the fact that it hit a wall. That video shows typical behavior, running code that is mostly copied straight out of the documentation. Most of the time, the robot will hit a wall and just keep going into it, oblivious to the collision. There is a “collision detection” function, but unfortunately, it rarely detects collisions when they happen. Hit something, turn around in a random direction, and repeat. I decided to start with a program that would just go straight until it Might be able to make a halfway decent toy for my cat to play with while we’reĪt work. It can be programmed via a stripped down javascript interface If it starts tipping over, the motor will generally turn off automatically until the robot sits upright. The toy is programmed so that it will try to stay upright as the shell rotates around it. The robot inside the shell is weighted like a Weeble such that it will normally sit upright. It moves forward by turning the spherical shell with wheels that rest against it. The robot itself sits in a spherical shell, like the hamster’s ball. Mostly only responsible for sensors, bluetooth communication, and some basic tasks,Ī Sphero moves sort of like a hamster in a hamster ball. Most of the computation being done on the controlling device. It is controlled remotely via bluetooth, with That started designing rolling robots at a very opportune time for some choice This Christmas I got a Sphero Mini robot, a little plastic ball made by a company
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