Why does dummies not follow their parent object's motion?

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biscuit122
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Joined: 23 Jan 2018, 16:16

Why does dummies not follow their parent object's motion?

Post by biscuit122 » 28 Nov 2018, 01:21

In general, dummies will follow their parent objects to move, even though they have been set kinematic constraints with corresponding end-effector dummies. But in hexapod.ttm mobile robot tutorial, all of dummies (such as 'hexa_base', 'hexa_footTarget0', hexa_footTarget1', ..., 'hexa_footTarget5') under 'hexapod', except for 'hexa_legBase', have no motion same with their parent object.

coppelia
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Re: Why does dummies not follow their parent object's motion?

Post by coppelia » 03 Dec 2018, 06:51

Hello,

in the hexapod example, IK works exactly as with any other dynamically enabled and IK controlled robot: the target dummy is moved to a desired position/orientation, and the tip dummy will follow.

Cheers

biscuit122
Posts: 28
Joined: 23 Jan 2018, 16:16

Re: Why does dummies not follow their parent object's motion?

Post by biscuit122 » 04 Dec 2018, 01:59

coppelia wrote:
03 Dec 2018, 06:51
Hello,

in the hexapod example, IK works exactly as with any other dynamically enabled and IK controlled robot: the target dummy is moved to a desired position/orientation, and the tip dummy will follow.

Cheers
Yeah, I know that. But in the moving process, dummy 'hexa_base' is set to move relative to dummy 'heza_legBase'. So their parent, pure shape 'hexapod', moves followed with 'hexa_base'. But at this time, 'hexapod''s child, dummy 'hexa_legBase' doesn't move followed with its parent. So I don't know why. I am look forward for your reply.

coppelia
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Re: Why does dummies not follow their parent object's motion?

Post by coppelia » 05 Dec 2018, 11:29

All 6 legs are individually controlled by moving the foot target dummies in relation to the hexa_base dummy. The hexa_base dummy is used to additionally allow for a different height or rotation of the body in relation to all feet. e.g. if all feet target dummies are left untouched, but you simply move the hexa_base dummy, then the robot will be able to move its body while keeping the feet in place (typically the movement sequence at the beginning of the simulation)

Cheers

biscuit122
Posts: 28
Joined: 23 Jan 2018, 16:16

Re: Why does dummies not follow their parent object's motion?

Post by biscuit122 » 08 Dec 2018, 20:35

coppelia wrote:
05 Dec 2018, 11:29
All 6 legs are individually controlled by moving the foot target dummies in relation to the hexa_base dummy. The hexa_base dummy is used to additionally allow for a different height or rotation of the body in relation to all feet. e.g. if all feet target dummies are left untouched, but you simply move the hexa_base dummy, then the robot will be able to move its body while keeping the feet in place (typically the movement sequence at the beginning of the simulation)

Cheers
Thanks for your reply. I think I have got that. But it cannot work on my own model. Do you know the reason?
https://github.com/feig122/force_test/b ... MODEL3.ttt

coppelia
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Re: Why does dummies not follow their parent object's motion?

Post by coppelia » 10 Dec 2018, 15:06

You haven't defined any IK groups or IK elements! Check maybe this tutorial.

Cheers

biscuit122
Posts: 28
Joined: 23 Jan 2018, 16:16

Re: Why does dummies not follow their parent object's motion?

Post by biscuit122 » 10 Dec 2018, 22:18

coppelia wrote:
10 Dec 2018, 15:06
You haven't defined any IK groups or IK elements! Check maybe this tutorial.

Cheers
Thanks for your help. It really made sense. Very appreciated!

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