ANTHONY NISTOR // DIGGER

Stackr Digger

A front add-on for Stackr that shows a parallelogram bucket, servo control from an Arduino Nano ESP32, and driving the arm from a phone gamepad.

WATCH THE DEMO VIEW THE PHOTOS
// SYSTEM ARCHITECTURE

How the Bucket Stays Level

Two long links run side by side from the red frame to the bucket. They form a parallelogram, so the bucket keeps its angle while the arm lifts. A shorter link and a servo horn tilt the scoop. An Arduino Nano ESP32 on Stackr drives the servos, and the SPad745 phone app sends those moves from a gamepad on the screen.

  • Parallelogram Arm The two long links stay parallel. Raising the arm lifts the bucket without tipping it, and a short link curls the scoop.
  • Nano ESP32 Servos Two micro servos sit in the frame. The Arduino Nano ESP32 on the robot sets their positions.
  • Phone Gamepad The SPad745 app puts a D-pad, two sticks, and face buttons on the phone and uses them to command the digger.
DIGGER_ARM.LOG ACTIVE
1. PAD

The phone gamepad sends a move

APP
↓ Set the servo angles
2. NANO

The Arduino Nano ESP32 drives the servos

PWM
↓ Raise or curl the scoop
3. ARM

The parallelogram lifts the bucket and keeps it level

LIFT
// DIGGER RUN

Digger Demo

The arm lifting and the bucket moving on Stackr.

DIGGER_DEMO.MP4 LIVE DEMO

Arm in Motion

This recording shows the digger in operation, with the parallelogram raising the bucket.

// HARDWARE & SOFTWARE

System Component Breakdown

01

Parallelogram

Two long links, a short curl link, and the bucket. The parallel links keep the scoop from tipping as it rises.

02

Micro Servos

A pair of servos in the frame. The parts laid out for the build are MG90S metal-gear servos.

03

Arduino Nano ESP32

The controller on top of Stackr. It takes the gamepad commands and sets the servo positions.

04

SPad745

A RobotiX One phone screen laid out like a gamepad: D-pad, sticks, A B X Y, and the shoulder buttons.

// PROJECT MEDIA

Build Photos

The printed parts, the arm on Stackr, the phone gamepad, and the CAD model.

On Stackr
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On Stackr

The red digger bolted to Stackr, with the Nano ESP32 between the side frames.

The Linkage
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The Linkage

The parallelogram, bucket, servos, and rear counterweight without the robot.

Printed Parts
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Printed Parts

Side frames, links, bucket, and the two servos before assembly.

Phone Gamepad
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Phone Gamepad

The SPad745 screen, with a D-pad, two sticks, and the face and shoulder buttons.

CAD on Stackr
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CAD on Stackr

The FreeCAD model of the digger mounted on the robot.

Arm Model
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Arm Model

The linkage by itself: long links, curl link, bucket, and counterweight.

Exploded Parts
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Exploded Parts

The FreeCAD model pulled apart: frames, links, bucket, counterweight, and the two servos.

// SLIDESHOW

All Project Pictures

12 photographs and drawings from this build.

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20261013_184559~2.jpg
// TECHNICAL SPECIFICATIONS

System Parameters & Metrics

PARAMETER SPECIFICATION / VALUE
Host Stackr
Mechanism Parallelogram arm and bucket
Servos Two micro servos; the build parts are MG90S
Controller Arduino Nano ESP32
App SPad745 phone gamepad
Structure Printed red frames, links, bucket, and counterweight
Design FreeCAD assembly