Hexapod Configuration

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02 Feb 2022 19:47 - 02 Feb 2022 20:32 #233825 by bw4257
Hexapod Configuration was created by bw4257
I'm looking for help in configuring a hexapod. I started with the hexapod simulator configuration and have modified it to use real hardware. I have been successful in moving the hexapod with the default joint values in kinematics.hal, however once I update the values to match my hardware, the motions don't make sense to me and the actuators try to go beyond their limits, etc.

I think I'm a little confused about what the values in the kinematics.hal represent or relate to. Specifically, I don't understand how to specify the actuator length, if the genhexkins.platform.[N].n values are relative to the platform coordinates and the genhexkins.base.[N].n are relative to the world coordinates.

I'll attach my configs files and would greatly appreciate ideas.

I've also attached a few pictures to show the joint coordinates.

 
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Last edit: 02 Feb 2022 20:32 by bw4257.

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08 Feb 2022 02:17 - 08 Feb 2022 18:57 #234316 by bw4257
Replied by bw4257 on topic Hexapod Configuration
Guess my last question wasn't specific enough.

I'm trying to update the values in kinematics.hal to match my real system and need assistance understanding a few details, specifically the unit vectors.

Using the values from the simulator, found here:

github.com/LinuxCNC/linuxcnc/blob/master...ematics/genhexkins.h

Let's focus on strut "0"

/* Default position of platform strut end in platform coordinate system */

#define DEFAULT_PLATFORM_0_X -1.000
#define DEFAULT_PLATFORM_0_Y 11.500
define DEFAULT_PLATFORM_0_Z 0.000

(x,y,z) <=> (-1,11.5,0)

/* Default unit vectors of platform joints axes in platform coordinates */

#define DEFAULT_PLATFORM_0_NX -1.0
#define DEFAULT_PLATFORM_0_NY 0.0
#define DEFAULT_PLATFORM_0_NZ 0.0

(x,y,z) <=> (-1,0,0)

Can anyone help me understand how this unit vector is calculated? Specifically, I don't understand how a unit vector can contain only an "x" component, if it's derived from values that have both and x&y component.

Any thoughts would be appreciated. Thanks for your consideration.

bw

 
 
Last edit: 08 Feb 2022 18:57 by bw4257.

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10 May 2022 05:18 #242462 by Drizzt
Replied by Drizzt on topic Hexapod Configuration
Have you figured out this issue, I'm also confused.

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10 May 2022 14:15 #242493 by bw4257
Replied by bw4257 on topic Hexapod Configuration
No...unfortunately not.

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