Animated Spider sculpture

The Hygroscopic Actuator (Passive Motion from Humidity) sounds like it would lend itself to a slow moving sculpture of a spider like creature mostly made of bamboo. Plan that one for me as a project.

Great choice—bamboo is light, strong, and beautifully suited to this kind of natural motion. Here’s a detailed project plan for your Hygroscopic Bamboo Spider Sculpture:

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🕷️ Project Title: The Humidity Spider

🎯 Concept

A spider-like kinetic sculpture that slowly raises and lowers its legs or changes posture in response to humidity, using plant-derived hygroscopic actuators made from bamboo and other natural fibers.

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🧩 COMPONENTS

🌿 Natural Materials

Bamboo segments: for body and limbs.

Pinecone scales or wheat awns: hygroscopic actuators (alternatively, carved thin bamboo strips).

Jute or hemp twine: tendon-like connectors or tensioners.

Wood glue or natural resin: adhesives.

Hardwood or thick bamboo disc: base structure.

Shellac or wax (optional): to seal parts that shouldn’t absorb moisture.

⚙️ Minimal Synthetic Add-ons

Tiny pivot pins: whittled wood, bamboo pegs, or small brass pins.

Optional moisture sensor or LED indicator (if desired for demo purposes—can be hidden).

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🏗️ STRUCTURE OVERVIEW

🕸️ BODY

A central bamboo segment, cut and sanded to resemble a spider’s abdomen and cephalothorax.

Eight bamboo legs, each consisting of two or three segments connected with wooden pins.

🦶 LEGS (Each)

The upper segment connects rigidly to the body.

The middle segment is joined with a pivot and includes the hygroscopic actuator.

The lower segment moves when humidity changes bend or unbend the actuator.

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🔁 HYGROSCOPIC ACTUATOR DESIGN

📏 Actuator Element

Thin strips of pinecone scale, wheat awn, or bilayer bamboo laminate.

One side more absorbent (untreated) and one side less (lightly waxed or sealed), causing curl under humid conditions.

🔩 Attachment

Fixed to the mid-leg section like a muscle or tendon.

When humidity rises, the actuator curls, pulling the leg downward or inward.

When dry, it straightens, lifting the leg.

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🔧 BUILD STEPS

1. Harvest and Prepare Materials

Choose dry-season bamboo for rigidity.

Collect or craft hygroscopic strips: ideally 2–3mm thick, 1–2cm wide, 10–15cm long.

2. Build the Body

Join two bamboo segments with a sloped cut.

Drill tiny holes to insert leg pivots.

3. Construct the Legs

Cut leg segments and connect them with pins for joint movement.

Attach actuator to the underside of the mid-leg joint using jute loops or natural glue.

4. Mount the Spider

Fix the spider to a hardwood or thick bamboo base so it stands above the surface.

5. Balance and Test

Adjust weight and actuator tension to ensure subtle, visible movement over hours.

Test in dry vs. humid environments (use a humidifier or water pan to simulate).

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⏱️ MOTION PROFILE

Speed: Ultra-slow. Changes may take minutes to hours.

Range: Several centimeters of leg movement depending on humidity swing.

Reversibility: Fully reversible with humidity cycling.

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🎨 AESTHETIC TOUCHES

Use contrasting waxed and raw bamboo for visual contrast.

Paint or stain body lightly with natural dyes.

Optional: add decorative jute “spinnerets” or mimic breathing motion with a subtle up/down body tilt.

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⚡ OPTIONAL ELECTRONICS (STILL MINIMAL)

Moisture sensor + LED glow for visual feedback in gallery settings.

Low-power heating wire hidden near actuators to speed drying.

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Would you like:

A sketch or rendering of this design?

Guidance on actuator tuning (for how much curl you’ll get with certain materials)?

A version adapted for a wall-mounted display or group movement like a swarm?

Chatgpt prompt about plant based actuator

Do you have an idea for how to make a motor or motion actuator out of plant derived parts with very minimal electrical parts?

Yes, you can make a motion actuator using plant-derived parts with very minimal electrical components by drawing inspiration from how plants themselves move—via hygroscopic, turgor, or biochemical swelling mechanisms. Below are a few ideas ranging from primitive to more sophisticated, but still mostly plant-based:

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🌿 1. Hygroscopic Actuator (Passive Motion from Humidity)

Example inspiration: Pinecones, wheat awns, seed pods.

Mechanism: Plant materials (e.g., pinecone scales, wheat awns) absorb or release water, swelling or shrinking and causing motion.

Build Concept: Attach thin, layered plant-based hygroscopic materials to a jointed structure. The motion is driven by moisture/humidity changes.

Control: Use a simple electric heating wire or sunlight exposure to locally dry the material.

Electrical need: Minimal—just optional heating or a small moisture sensor.

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💧 2. Turgor Pressure Actuator (Water-Powered)

Example inspiration: Mimosa pudica (touch-me-not), Venus flytrap.

Mechanism: Living or preserved plant tissue (e.g., parenchyma) swells or shrinks with water pressure, changing shape or creating force.

Build Concept: Use plant-based bladder or fiber tube chambers that inflate using gravity-fed or solar-pumped water, causing controlled flexing or bending.

Control: Valves and gravity; optionally a solenoid valve with a timer or water sensor.

Electrical need: Very minimal—one low-power solenoid if needed.

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🧵 3. Biopolymer Coil or Strip Motor (Swelling-Based Linear Motion)

Example inspiration: Spiraling seed structures or the awns of wild barley.

Mechanism: Laminated or coiled strips made from plant fiber (like cellulose or lignin-based material) expand unevenly when wet or warm, causing bending or rotation.

Build Concept: Wind a thin hygroscopic plant-fiber strip into a spiral. One side is more absorptive than the other. Moisture triggers the coil to twist.

Control: Passive environmental exposure, or controlled moisture/humidity chamber.

Electrical need: None or optional sensor/feedback.

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🔥 4. Thermal-Bimetal Style Biocomposite Actuator

Example inspiration: Thermally active seed dispersers (like geraniums or Erodium).

Mechanism: Two bonded plant-based materials with different thermal expansion coefficients.

Build Concept: Composite strip of e.g., bamboo bonded with waxy bark, bending when heated (via sunlight or resistive heater).

Control: Small electric heater, passive solar, or firefly circuit.

Electrical need: Minimal—just heating or sensing.

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⚙️ 5. Manual Wind-Up Bio-Motor with Biodegradable Spring

Example inspiration: Twisted tendrils and woody vines.

Mechanism: Coiled plant fibers like willow, jute, or hemp store and release torsional energy.

Build Concept: Wind-up spring made of steamed, coiled vine or bark that tightens and unwinds under tension.

Control: Manually wound or slow release via humidity/moisture weakening one section.

Electrical need: None.

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Would you like one of these designs expanded with diagrams, materials list, or a small prototype concept using common tools?

Chatgpt conversation about plant powered action

Using an aeroponically grown plant to provide periodic low-power energy to a small robotic device is a fascinating and unconventional idea. While plants are not natural batteries, there are a few emerging and experimental ways to extract usable energy from them. Here are some options:

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⚡ 1. Plant Microbial Fuel Cells (PMFCs)

How it works: Microbes in the root zone (rhizosphere) of the plant break down organic matter and release electrons, which can be harvested using electrodes.

Aeroponic adaptation: Although PMFCs are typically used in soil or hydroponics, you could add a microbial substrate chamber beneath or around the root misting zone to support electroactive bacteria.

Power output: Microwatts to milliwatts per plant. Enough to charge a capacitor over time for intermittent bursts.

Pros: Can operate continuously and is renewable.

Cons: Complex to maintain in purely aeroponic setups; efficiency is low.

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🔋 2. Photosynthetic Energy Harvesting (Bio-Photoelectrochemical Cells)

How it works: Harvest electrons from photosynthetic activity—plants naturally move electrons during photosynthesis, and researchers have tapped into this.

Setup: Embed electrodes near or within the plant leaves to capture photo-induced electron flow.

Power output: Very low (nanowatts to microwatts), but can trickle-charge energy storage.

Pros: Direct use of light energy; no microbes required.

Cons: Very experimental, fragile setup, sensitive to light cycles.

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🧪 3. Plant Thermoelectric or Triboelectric Harvesting

Thermoelectric: Use tiny temperature gradients between plant surfaces and the air to generate power with thermoelectric materials.

Triboelectric: Harness small movements of leaves or stems (from wind or vibration) to create charges via friction.

Pros: Low infrastructure needs, simple components.

Cons: Irregular, small output; may not be sufficient without amplification or energy storage.

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🌿 4. Capacitive Discharge from Plant-Generated Electrostatic Fields

Conceptual idea: Some studies have shown that plants generate small electrostatic fields as ions move through their structures (especially during transpiration).

Experimental: Place capacitive plates near plant tissues and extract small potential differences.

Power output: Very small and variable; useful only for slow capacitor charging.

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🔁 5. Hybrid System: Plant + External Enhancements

Combine the plant-based energy source with a secondary system like:

Tiny photovoltaic cells placed among the plant leaves (plants act as both power source and camo/habitat).

Miniature piezo generators activated by plant movement or water droplets in the mist system.

Scheduled capacitor discharge to a robot actuator or sensor.

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⚙ Use Case in a Robot

Given the low and irregular power output of plant-based systems, the robot would need:

Ultra-low power electronics (e.g., sub-threshold logic processors, deep sleep modes).

Capacitor or supercapacitor for energy buffering.

Periodic activation cycles (e.g., collect data every 15 minutes, transmit once per hour).

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Summary Table

Method Power Output Aeroponic Suitability Notes

Plant Microbial Fuel Cell µW–mW Medium (with substrate) Needs microbial zone

Photosynthetic Harvesting nW–µW High Light-dependent

Thermo/Triboelectric Harvest nW–µW Medium Needs motion/temp difference

Electrostatic Harvesting <µW Low–Experimental Mostly theoretical

Hybrid with PV or Piezo mW (combined) High More reliable

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Would you like help designing a small circuit or power budget for such a setup?

One spider leg, dancing

I am claiming the points for having completed my experiment with machine-learning AI doing the dull parts of programming the movements of a single spider's leg.  

I ran something over 3000 leg movement actions (only a proof of concept, not enough to get any real skill learned in) directed by a reinforcement learning agent using a tensor-flow based SARSA agent.

Most of the code came from Gelana Tostaeva in an article she published through Medium named 

Learning with Deep SARSA & OpenAI Gym.

After that 3000 steps, I learned something important.  The agent was learning from it's experience, using my 4 servo spider leg, and the python code I wrote to represent the spider leg as an Open AI Gym environment.  My reward code was allowing it to learn to make big dramatic gestures without actually overheating the servos. Mwahahahaaa.  

(There were a bunch of non-zero values in the Q matrix when I stopped, indicating some bits of learning, I believe) 

However, eventually the jerky, fast, full arc, drama of the gestures did overstress the servos and break the gears in one.  I expect it might eventually learn that it has to ease up to full speed and ease back to a stop.  However to save on costs, I will be futzing with the reward design a bit.  Thanks Gelana!

Leg Agency

I have been rewriting some python code to be multiprocess so that it can be writing and reading from the serial port "at the same time".

That is in good shape now, though I worry a bit about how many processes I have broken the work up into.  There is a monitor process and then two for each serial port that has servos attached (one reads and the other writes).

I took sample code from "Create custom gym environments from scratch — A stock market example" by Adam King on Medium.  That gave me the methods required for a wrapper.  That code makes my multiprocess SpiderWhisperer comply with the gym environment API from OpenAI.  

In order to have an RL agent learn how to move my spider leg while only developing the sort of familiarity with actual machine-learning math that one gets from sharing a friendly nod across a noisy party, I stripped out pieces of sample code from the Gym tutorial here.  That gave me the rest of the code I needed for some conceptual experimental runs.

I hesitate to mention that there was some debugging.  Since I am intent on learning from the noble creatures in the phylum arthropoda, I will say that some adjustments to the implementation were required that I discovered by trying to run the RL scenario using code I shuffled together.

Now I am ready to try a long run, and see if an RL Agent that could learn to maneuver a cart up a mountain from a valley, can also learn to make interesting movements with a 4 servo spider leg, without burning out a lot of servos.

Spider Leg exercises in the Gym

After doing some more thorough reading and experimentation with the tutorials, I have decided that the Google Deep Mind control components are more heavyweight than I need.  They have a dependency on a pay-to-license physics simulation engine that I don't need, mujoco.  So instead I am narrowing my list of components some, to deep mind acme (dm_acme), the deep mind environment (dm_env) package, and openai gym.  Together they provide a framework for easier implementation and a sample case of reinforcement learning agents.

ps: If you read this post aloud to someone, be thoughtful how you place the pauses when you say "google deep mind control".  

Deep Minded Acme Spiders

The Google Deep Mind projects include some demos and examples that sound like an excellent base for what I want to try for the SpiderDroid.  Now let us see if I can absorb enough new comp sci concepts to produce any interesting behaviors.