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Topic: Can this work? (Read 929 times) previous topic - next topic


Hi, I have two different questions (but about the same robot concept)
(Q1 is related to programming and feasibility, while Q2 is a mechanical question)

Assume this is a side view of a simple '2 wheeled' balancing robot:

The difference is that both legs have got 2 additional servos as shown (black).
Note: x denotes 'center of gravity' and --- is the accelerometer+gyro.

Now, lets say that (in a particular situation) the robot is to lift itself upwards from 2nd pic to the position in 1st pic, without translating horizontally !

Q1. Is it possible for it to dynamically vary the 2 servos orientation to "balance itself" as well as "lift itself slowly", while keeping its wheels fixed. (and of course with a varying and inclined acc+gyro board as shown) ?

Q2. Assume that the length of both bars are 15cm each, and the torque of both servos are 15kg-cm each. Now, if the servos rotate in the direction shown (to lift itself up), would the two servos "help" each other? (would the torque required to lift the robot be divided among the two servos?).

Generally, with 1 servo, the robot would be able to lift 1 kg weight [ Torque = Force x 15cm ]
but would the torque of the upper servo add up to the total torque? hence allowing 2 kg weight to be lifted?
[note: I mean, 2 kg with 2 servos - the whole robot of 4 servos would lift 4 kg - if I am not wrong]

I am not sure if I explained everything properly, please let me know if you want me to clarify things.

Thanks !


Feb 26, 2011, 11:54 pm Last Edit: Feb 27, 2011, 12:12 am by Hasan999 Reason: 1
@KE7GKP:  Thanks !

And sorry, I admit, the drawings are confusing..

The two servos are the Thick Black circles (the red marks in Q2), the bottom servo rotates the bottom bar, and the upper servo rotates the upper bar. [the lower most circle is the wheel CR servo]

The reason I showed the 'body' at that angle is because of the rest of the mechanical design that forces it to be inclined (along with acc+gyro). - correction: you're right, it would not be parallel to the bar.

And regarding the "wheels fixed", I meant, the CR Servo will hold the wheels at Speed = 0.
But yes, as you explained, it is not feasible with that condition !

Anyway, thanks for the quick reply.

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