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POST No. 2407927
Positional values for 0 and 360 degrees
2020-08-03 06:15:04 robotiscustomer

Hi, given that the range of positional values is between 0 and 4095 and 180 degrees corresponds to 2048. What is the positional values for 0 and 360 degrees? I have no plan to make the dynamixel to turn like a wheel.


By calculation: 90 degrees = 1024, 270 degrees = 3072, 360 degrees = 4096 which is outside the range of [0, 4095]. Is 0 degree = 0 positional value, 360 degrees = 4095 position value even by calculation, it should corresponds to 4096? 


Please clarify.

2020-08-03 06:15:04
robotiscustomer
2020-08-03 13:48:22 Will Son

Hi,


Under the Position Control mode, DYNAMIXEL won't cross the 0-360 boundary.

Although the magnetic encoder reading of 0 - 4095 is mapped into 0 - 360 degree range, 4095 cannot be a 360 degree which is identical to 0 degree in a single rotation.

Thank you.

2020-08-03 13:48:22
willson
2020-08-03 23:31:26 robotiscustomer

Thanks Will. So what position values do I use for 0 and 360 degrees? Do you mean I use position value 0 to correspond to 0 degree and 4094 to approximate 360 degrees?

comment
2020-08-04 08:57:57 willson
I need to confirm with the dev team, but I believe 4095 is one tick away from 360-0 crossing point.
You can use 0 - 4095 within a single rotation.
2020-08-04 08:57:57
willson
2020-08-05 07:03:36 robotiscustomer
Thanks. Please checked with the dev team.

Dynamixel Wizard accepts values up to 4095 which turns to make the dot on the horn pointing down. When I entered 0, the horn also turned and the dot pointed down. The two locations might be next to each other with one tick away. I need to know how it works under the Linux version of Dynamixel SDK and U2D2.
2020-08-05 07:03:36
robotiscustomer
2020-08-03 23:31:26
robotiscustomer
2020-08-06 12:49:45 robotiscustomer

Hi Will, have you heard from the dev team? 


If my simulator generates +-degrees with 0 as the home position, is it better to use Position Control Mode or Multi-turn Mode? In my robot, some motors will be oriented with the horn on top of the Dynamixel label but some may be oriented upside down.

2020-08-06 12:49:45
robotiscustomer
2020-08-10 14:23:26 Will Son

Hi,

I've confirmed that 4095 - 0 will differ by 1 tick of encoder reading as 4096(which does not exist in Position Control mode) is theoretically equal to 0.

When usually assembling DYNAMIXEL to inverted position, we assemble the frame in a way that DYNAMIXEL only travels within a single rotation.

If your application requires multiple rotations, you should use Extended Position Control mode.

Please be aware that rotational information will be reset after the power switch or specific conditions.

https://emanual.robotis.com/docs/en/dxl/x/xm430-w210/#operating-mode11

Thank you.

2020-08-10 14:23:26
willson
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