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Take a look at the following picture. I'm wondering how $\theta_3 -90^\circ$ appears in the table. As far as I see from the way axes arranged, it is only $\theta_3$.

enter image description here

CroCo
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1 Answers1

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Usually, this type of offset comes from the fact, that you want to corelate your actual angular values of your joints (motors) with your kinematic model. Most probably the hardware in the configuration chosen in the image has the joint coordinates $(0, 0, 90)$. So adding that -90 offset accounts for discrepancies between the theoretical kinematic model and the actual joint angle value for the respective position of the hardware.

50k4
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  • that was my first thought. I've double checked the documentation of the device. I couldn't find the zero configuration of the device. – CroCo Dec 08 '21 at 20:57