Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: gfscustoms on September 25, 2008, 08:02:44 PM

Title: My Hexapod design (pics), servo choice help...
Post by: gfscustoms on September 25, 2008, 08:02:44 PM

Hello, I am currently designing and getting ready to build a small hexapod. In total it will have 14 servos, webcam, distance sensors, foot touch sensors,  etc...

My question is about the servo's I am going to use. I am looking at using the HS475HB servos (76oz-in). They are at the upper end of my budget, but I want to make sure that they will have enough torque to move this along. I cannot estimate the weight of the robot, but it is mainly the weight of the 14 servos controller, and battery.

For the controller I have a CMU Qwerk, so I plan on making this tele-operated via onboard wi-fi, and controllable via Ipod Touch and or laptop.

Will these servos have enough torque based on what I've said? Any suggestions?

Here are a couple of pictures, this is still in preliminary design, so it is more of a schematic drawing.

http://img.photobucket.com/albums/v146/gscustoms/RobotRev5-1.gif
http://img.photobucket.com/albums/v146/gscustoms/RobotRev5-2.gif
http://img.photobucket.com/albums/v146/gscustoms/RobotRev5-3.gif

Also eventually as funds become available, I will be using these components for a larger more complicated bot:
http://img.photobucket.com/albums/v146/gscustoms/robot1.jpg
http://img.photobucket.com/albums/v146/gscustoms/robot2.jpg

Title: Re: My Hexapod design (pics), servo choice help...
Post by: benji on September 28, 2008, 09:20:30 AM

once i did build a hexapod of 12 servos and some other stuff , it weighted almost 2.5 kilos and the servos didnt suffer at all
i used the hitec HS-322HD

Title: Re: My Hexapod design (pics), servo choice help...
Post by: Admin on September 30, 2008, 04:12:36 AM

To calculate torque, you need to know both weight and the length of the legs. Also, you need to know the minimum number of legs that will always be on the ground, and how far they stretch out per step.

You'll have to estimate the weight as best you can. Otherwise its just guessing :P
If you don't, there is a chance the servos won't be strong enough and be a huge waste of money.

Read this, it'll help you understand the math a bit better:
http://www.societyofrobots.com/mechanics_statics.shtml