Lynxmotion biped waist twist torso frame parts recommendation needed

Lynxmotion Legged Robots
1

I am looking to make a humanoid biped torso with a waist twist motion similar to this picture from the Lynxmotion website but I am unsure as to what the parts are.

The torso needs to be able to hold the standard size servos for the waist, hips and shoulders plus an additional servo in the top center facing up for a RB-Lyn-77, Lynxmotion Pan and Tilt Kit / Aluminium, for the head.

The shoulder, hip and neck servo placements should be similar to the RB-Lyn-124 Lynxmotion Humanoid Biped Torso - A (no servos) BT-01 with the addition of the waist twist.

i1112.photobucket.com/albums/k494/franknjim/wastro21.jpg

2

I was planning on going with the following digital servos running at 6v for higher torque levels.

HS-5485HB for hands, wrists and head.
Torque: 72 oz-in at 4.8V
Torque: 89 oz-in at 6V

HS-5645MG for feet, legs, hips, shoulders and upper arms.
Torque: 143.03 oz-in at 4.8V
Torque: 164.2 oz-in at 6V

HS-7955TG for waist.
Torque: 249.96 oz-in at 4.8V
Torque: 333.29 oz-in at 6V

I’ll work on making some drawings.

3

I decided against the twist torso until I get a little experience first. I’ll just go with a normal humanoid torso to start with.

Here is the parts list and drawings.

1 RB-Lyn-124 Lynxmotion Humanoid Biped Torso - A (no servos) BT-01

1 RB-Lyn-1255 Lynxmotion Black Aluminum Robot Feet (Pair) ARF-01

2 RB-Lyn-133 Lynxmotion Robot Hand - A (no servos) RH-01

9 RB-Lyn-81 Lynxmotion Aluminum Multi-Purpose Servo Bracket Two Pack ASB-04

1 RB-Lyn-83 Lynxmotion Aluminum “L” Connector Bracket Two Pack ASB-06

4 RB-Lyn-101 Lynxmotion Aluminum “C” Servo Bracket with Ball Bearings Two Pack ASB-09

3 RB-Lyn-103 Lynxmotion Aluminum Offset Servo Bracket with Ball Bearings Two Pack ASB-11

2 RB-Lyn-102 Lynxmotion Aluminum Long “C” Servo Bracket with Ball Bearings Two Pack ASB-10

10 RB-Hit-86 Hitec HS-5485HB Standard Karbonite Gear Digital Universal Servo (hands. Wrists, arms)

Torque: 89 oz-in at 6V
Length: 1.57" (40mm)
Width: 0.78" (20mm)
Height: 1.45" (37mm)
Weight: 2.29oz (65g)

16 RB-Hit-60 Hitec HS-5645MG High-Torque 2BB Metal Gear Universal Servo (Legs, Arms, shoulders, hips)

Torque: 164.2 oz-in at 6V
Length: 1.59" (40.6mm)
Width: 0.77" (19.8mm)
Height: 1.48" (37.8mm)
Weight: 2.11oz (60g)

4

Here is a shortened version of the arm with a smaller hand.

LynxmotionArmShortened.jpg
LynxmotionArmShortened.jpg819×1076 76.1 KB

5

Here is the arm without the elbow tilt.

LynxmotionArmShortenedV2.jpg
LynxmotionArmShortenedV2.jpg768×902 58.3 KB

6

This one will give me a bendable elbow with just one DOF for the hand.

LynxmotionArmShortenedV3.jpg
LynxmotionArmShortenedV3.jpg756×1040 58.1 KB

7

Is the V1 Erector Set going to be continued once the V2 Set comes out?

8

Very cool (and very experimental) project.

Start making a list based on section:

  • Upper torso (with rotate feature)
  • Lower torso
  • Arms
  • Head
  • Legs

We also suggest making a stick figure clearly showing which servos you plan to use and where. This will also help you determine which brackets would be best at each location.

We’ll be happy to review it. Note that you may need 1/4 scale servos in the legs since 645MGs may have issues lifting the weight of a full humanoid with wrist rotate and hands.

9

Your arm is going to be way too heavy for the legs to support it, and may even be too hard for the shoulder rotate to lift it up. You might try simplifying the design to something like the KHR-2HV:
robotshop.com/kondo-khr-2hv-humanoid-robot-3.html
This can be easily reproduced with the SES Brackets.

10

You may want to try initially without the elbow tilt since even without it, the arm will have 4DoF. It’s always best to minimize the DoF initially to ensure the robot works, and only then start to add additional DoF.

11

2x RB-Asb-04 would make for a short arm, whereas replacing them with 1x ASB-15v2 would make for a longer arm and look like it includes an “elbow”. The choice is yours.

12

As you can see - there’s no right or wrong answer, and there are many possible combinations.
The general rule of thumb is to keep things simple, get it working, and then add to it.
Try your best to plan for future additions / improvements.

13

The SES V1 kit, set to be released late May 2013, is based on the current SES servo brackets, which use Hitec servo motors. Therefore it is compatible with all current SES brackets. The general idea behind the kit is to allow customers to build a variety of robots rather than having to purchase each robot (and spend a lot of money).