Introduction

My idea is to build an electronic stargazing/Binocular chair that can hold a person sitting on it, with the motors to control the two rotational axes and realize the GOTO system (which means the computer can use the celestial body coordination database to point the telescope/binocular automatically)

1. A historical survey of StarChair

The Sky Rover StarChair was a short-lived commercial product marketed as a motorized reclining “stargazing chair.” Released in the early 2000s under the Sky Rover brand, it was designed to let users comfortably track the night sky by tilting and rotating while lying in a zero-gravity style seat.

Although the idea attracted attention in astronomy and hobbyist communities, the chair was discontinued after a relatively brief market presence. Reports suggest that high manufacturing costs, limited demand, and mechanical complexity contributed to its withdrawal. Today, the StarChair survives mostly in references on enthusiast forums and product archives, with no active production or direct successor models.

In 2004, when it came out, it was labeled as $ 3950, made in Australia; now it even needs around $ 7000 to buy it since it stopped manufacturing and selling. The structure of it is not so complex, and computer technology has developed a lot over the past 20 years. It shouldn’t be very hard to make a DIY one nowadays

2. Lots of amateur Astronomers tried this idea with the manual version:

1)Custom Binocular Chair with bike wheels and zero-gravity chairs

Binocular chair stargazing, with comfort and stability

2)Another similar version with a zero-gravity chair and an alpenstock to rotate:

DIY Astro Binocular Chair - YouTube

But I doubt the zero-gravity chair can be very useful for my GOTO system, since the rotation of that for pitch angle might not be linear. But the rotatable base plate design is useful for reference.

3)Gary’s Motorized Big Bino Chair

Also, with a zero-gravity chair but it can rotate the base plate with an electric drill?!

By the way, the design with some elastic rope to balance the angle of pitch can be a good idea?

4)A book systemically introduced about the homemade Binocular chair:

link.springer.com/content/pdf/10.1007/978-3-319-46789-4.pdf

5)A Post with discussion about the body weight problem, portable design and even the vibration from heart beating:

Motorised Binochair design for 100mm binoculars - Discussions - Binoculars - Stargazers Lounge

3. My first prototype of a manually rotatable chair

During week 7: “How to make something big”, I decided to make a prototype of a stargazing chair for my final project. More detailed processing documentation can be found in week 7: Huanyu HTMAA 2025 week 7

Based on the experiment, I found that the pitching axis of this design is very unbalanced, as expected. And the cheap Oriented Strand Board is not strong enough, which will distort and cause the binoculars to change position. Here is a photo taken by Anthony showing my in-class presentation of the prototype that I couldn’t get up by myself because of the chair’s unbalanced structure.

However, I bought a big Lazy Susan 20-inch turntable bearing from Amazon, and it is strong enough to support my horizontal rotation axis: (20-inch commercial one). It was not tested on a prototype because of the delayed shipment and the missing round base after the class, but it would work well, and my future design will focus on using it.

4. The astronomical AI chatbot on the chair

Apart from the complex mechanical design and motor controlling problem, I also have an idea to make the smart chair more interesting: design a device on the chair that is connected to AI through the internet to chat with users about astronomical knowledge when they are doing stargazing. My own observing experience told me that it will become boring easily if you look at stars for the whole night, especially for the general public, and they always ask strange questions like the distance of some stars, which can be hardly remembered, but can be easily and accurately answered by a modern LLM model like ChatGPT. The scientific reliability of ChatGPT nowadays is good enough for most public science scenarios.

To achieve that result, there are lots of existing examples that I can learn from (example: ElatoAI - Realtime Speech AI Agents for ESP32 on Arduino). As a result, during weeks 9&10&12, I will focus on the microphone, the speaker, and the networking system building for this sub-system of my smart stargazing chair. This chatbot is named as “IRIS”.

Relevant progress:

Week 9: input devices & microphone Huanyu HTMAA 2025 week8

Week 10: output devices & speaker Huanyu HTMAA 2025 week9

5. The material and design of the new rotatable base plate:

To get stronger material for my new chair base plate, I went to The Home Depot to buy the new wood plates. I finally decided on the 2-foot*2-foot square 5-layer plywood board (~$10/each) since it’s cheap and easy to bring back (I don’t have a car). And this size is good for the base plate, so I don’t even need to machine the outline. It can rotate smoothly when it’s between two boards:

The idea of adding the stepper motor to drive it: dig big holes in the center of two base plates, and set the smaller gear ring in the middle, also set the stepper motor at the center to be hidden in the big rotatable bearing. The biggest issue is how to get the gear ring. Too big one should be expensive and heavy, and I might need to consider using a waterjet machine to cut the gear ring.

For the pitching axis, because it might not be balanced so I need the big torque output from the motor. A small one without efficient reducing can’t give me enough torque. Jiaming mentioned he has one extra big motor that can fit my requirement, which looks like this: (12 Nm torque), and I still need to figure out how to design the mechanics of the pitching axis and drive it.