Mechanisms

By Dan Chen, March 5, 2015

The goals for this week is trying to model Modular Self Assembling  Robotic Arm.

4 major modules

1. Base module or moving plateform
2. Lifting Module
3. Rotating Module
4. Grabbing Module

Options for Lifting (Arm) Mechanisms

Direct Drive with Servo
Pros: Takes up less Space
Cons: Less Torque
Timing belt
Pros: High Torque
Cons: Heavier? Require additional encoder

Actuator
Pros: High Torque
Cons: Takes up more space, expensive.
Parallel-mechanism drive by servo
Pros: High Payload
Cons: Takes up more space, expensive.

5th Option? Boston Dynamics’s Spot? 

 

Parallel-mechanism Design & Test

For parallel-mechanism, I tried to model after this Kuka Robot below. For a module system, this might take up too much space.

 

Self Assembling / Dissembling

Requirements

1. Click / Snap on (Magnet)
2. Data & Power Connection (Pogo Pins)
3. Stiff Linkage
4. Detachable (solenoid)

Self Alignment & Snap Test

I set out to create an interlocking system that can be roughly aligned and clicked in place by magnets. The spot where the two module meets would also have a pogo pin to provide power and data, probably serial communication. If the weight requirement allows I might add a solenoid for detaching the modules.

Take aways: To crate a rough meeting surface that gets attracted by magnet it’s generally a good ideas have a large opening then guiding the structure to a fixed point. To make the modules stuff, it’s good to have corners that locks together after the rough alignment.

 

Version 2

Future versions should include stiffer join, adding a servos for locking each module.

Combine Clickers and Servos

 

How does it work?