# Inverse Kinematic system

 IK system provides more control over characters and their behavior. It is one of the ways to animate characters, and allows to control the position of the character's limbs at a certain point / position (arms, legs, tails, etc.) while allowing natural behavior from the limb. Just as an example – IK allows to correct the position of the foot on a rough surface, adjust the natural behavior of the hands of a character getting up from the table, etc.

With IK in Tvori there are multiple valid solutions for any given input via controller. For example, once you move a hand palm, an arm and a wrist adjusts their position. So only one bone is manipulated, but the rest of the body is also automatically rigged to it.

{% embed url="<https://youtu.be/HEgkjBW1V5U>" %}

### IK types &#x20;

IK system in Tvori has three modes: **basic IK**, **IK for arms** (with additional logic for the natural behavior of the clavicle), **IK for legs** (with additional logic for controlling the feet).&#x20;

![](/files/-MLhZUCKFjnTUVKaJzqi)

#### **IK: use case**

**IK** (or Simple IK) is a classic animation option, which is utilized for a one controller with 2 bones. This setup might be applied to thumbs, hair and other minor body parts.

![We recommend Simple IK  for modeling the mechanical objects or robot-alike object types](/files/-MLha18gg55h0hXTS0SK)

#### &#x20; **Leg IK: use case**

&#x20;**LegIK** is a more advanced system, compared to the Simple IK, due to usage of the controller with 2 bones manipulation.

<div align="center"><img src="/files/-MLhbuzCQMYuMpTi2OM2" alt=""></div>

![](/files/-MLhcwrj9Zp2anyn9zDp)

&#x20;**Arm IK: use case**

The last but not the least is the new IK setup panel for arms, even though it can be controlled via FK as we mentioned before.&#x20;

&#x20; Moreover, the main difference between ArmIK and both Simple IK and LegIK is an *automatic correction of the clavicle position*. Via 1 controller you are enabled to align all arm bones starting from a clavicle to hand wrist and palms. You can use Arm IK not only on the entire hand, but for the hand wrist, particularly. Besides that, there is an additional controller for shoulders.

![   ArmIK as a convenient tool when you need to freeze a hand position in the space](/files/-MLhe1aEhTWvjV9RTTbo)

![](/files/-MLheQhveK7yIPnAd35M)

### IK controllers modes & animation

&#x20;Tvori has a switching function to the **free editing mode** of the Goal Target or/and default procedural mode, where you're only able to adjust an angle. The Goal Target assists to control and guide character's elbows or knees in a desired direction.

![](/files/-MLhgIuAXk2V1Z9U61Dy)

&#x20;IK controllers  support realtime animation and autokey modes.

{% embed url="<https://youtu.be/7UAgfqwMig4>" %}


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