Dash Robotics

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A speed test video, and getting the gear ratio right

Now that the campaign has wrapped up, we're heads down in development mode, refining all the things that will make the robot you saw in the video an awesome product that you get to enjoy. 

 

There are lots of aspects to this, the main ones being chassis, powertrain, electronics, and control (the mobile app). Every week we will highlight part of our progress here to show everyone how things are going and what it takes to turn a research prototype into a fun toy that anyone can use.

This week I'd like to highlight some work from the powertrain side. The powertrain consists of the motor, a transmission housing, and a few gears. Those gears ultimately drive Dash's structure, moving his hips and legs, making him run across the ground.

It is important to determine the best gear ratio. This is a tradeoff between speed - how fast Dash can move his legs, and torque - basically how much force the legs can put out. To figure this out, we're taking high speed video to watch how Dash runs. Right now we're using a 16:1 gear ratio. If we had a higher gear ratio, Dash would have a slower top speed, but would have more torque to say, get over obstacles or push things around. A lower gear ratio would make for a faster, but not as strong robot.

To get the balance just right, we've started to take high speed video of Dash to see how fast he runs with the current gear ratio. This video shows Dash running at full speed, captured at 100 frames per second. This means it's playing back slowed down by 3.33x. The tape marks a specific distance so we can calculate the speed. Looks like about 6 ft/sec! Not bad for a robot only 4 inches long. That'd be like a 6 ft tall person running at over 70 mph...

 

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