First robot remote driving test

I programmed some remote control software using a Golang receiving program on the robot and a ruby control client using my gamepad ruby gem and an xbox1 controller. It worked OK. It was a bit jerky, there’s no PWM so no acceleration, it’s either go or stop; anything not totally rigid on the robot wobbles. Also the position of the camera doesn’t show enough of the robot so it’s hard to get a real idea of where the robot is.

I was filming, the robot was being controlled my my wife, Morwenna, from upstairs.

The robot is also prone to shed a track if the “half turn” is used too much, that is one track forwards or backwards, the other one stationary. I can fix this in software if I can work out a way to do PWM on the robot that doesn’t run the Raspberry Pi CPU.

Tagged ,

Rejects and prototypes

Prototypes and rejects from the 3d printer. All part of the design process for my robot:


Tagged ,

New robot base design and completed prototype arm assembly

I spent all day at hacman Tuesday and Wednesday printing and tweaking robot parts. I put it all together when I got home. This is the front, the lifter arm has holes to allow me to screw in different attachments, I’ve still not designed that part of the robot yet:


Here is the back view, you can see the lifter arm gear housing (the curved structure) and the motor that drives it, also the battery (underneath the ball hopper)


The lifter arm gear system looking through where the hopper would be:


I need to design an attachment for the end of the lifter arm. Here I’ve created a simple one using meccano. It’s too heavy, the bolts catch on the floor and it dumps the ping-pong balls short of the hopper. Other than that it’s perfect. You can see the camera with capped lens that I’ve just wedged into the structure temporarily:


Next-up: better lifter attachment design, a couple of re-prints with tweaks and some software.

Tagged ,

Testing the new battery + lifter arm circuit

First test of the Raspberry Pi running off battery power with no external supply at all. In the picture the 5000mAh battery is the object at the back with “5000” written on it. My multimeter is measuring the voltage output. One of the Raspberry Pi (the thing with the red light on it) output pins is connected through the MotorPiTX board (the yellow circuit board on-top of the Raspberry Pi) to the breadboard.

The breadboard contains two circuits, the top-right cluster of components is the circuit that turns the output of the Raspberry Pi into something relevant to the motor driver in the bottom left, the bottom left cluster of components is the motor driver itself.

The Pi is pulsing the output causing the motor driver to spin the motor. The micro-switch just on the very bottom of the picture is one of the limit switches for the ball lifter arm.


Tagged ,

An assembled hopper

Today I printed out and glued together the first iteration of the ping-pong ball hopper that takes up most of the space of the robot.

The assembled hopper:


Full of ping-pong balls, I can get 12-14 in without packing them manually. That seems like enough for now, but a larger hopper would be good.


Mounted on the robot. You can see the completed camera mount and Raspberry Pi mounted on the side in the foreground:


The reverse angle:


Tagged ,

Testing new motor mounts

I needed to re-design the motor mounts on the robot base, they didn’t hold the motors securely enough and tended to shift around.

The new mounts are better fitting and include a small wedge that fits between one of the gearbox plates where there are no cogs.

Testing new motor mounts Testing new motor mounts

One of the great things about 3d printing is being able to pull out part of a design and iterate over in isolation, then when you’re done incorporate it back into your main design.

Tagged ,

Raspberry Pi camera mount + lens holder

I printed out the front half of my Raspberry Pi camera module mount. It serves two purposes, providing a way of mounting the camera on my robot, and giving me a place to attach the wide-angle lens I’d bought earlier.

Raspberry pi camera holderRaspberry pi camera holder

Tagged ,

New Pi mount, and testing the power requirements

Testing the robot power requirements

Before I pick a battery I need to know what power requirements my robot is going to have so I took it into the hackspace to test. I hooked it up to one of the power supplies then ran all the systems, so Streaming video off the Raspberry Pi over wireless whilst running the motors. I weight it down with a large motor (the big black thing) and then provided resistance, it peaks at about 1.6 amps.

In the video you can also see the new side mounted Raspberry Pi and the base of the ping-pong ball hopper.

Detail view of the side mounted Raspberry Pi and the base of the ping-pong ball hopper:

Raspberry Pi mount and ping-pong ball hopper base

Tagged ,


The Raspberry Pi camera doesn’t have a field of view that is wide enough for my robot, I’d have to mount it really far from my robot to see enough context to make it drivable so I’ve bought some wide angle iPhone lenses to try out.

Wide-angle and fish-eye lenses

Here’s a photo taken using the fish-eye lens held up to my iPhone:


Tagged ,

Get every new post delivered to your Inbox.