scorbot_controller

Scorbot Robot Controller

Description

Arduino-based motor controller and software for rescued Scorbot ER III robot arm.

Video of Scorbot start up and simple motion demo

Potential Future Steps

The project is complete as a demostration of reviving the Scorbot, but future exploration could include:

• [] add direct joystick control
• [] add Microbit remote control for student project
• [] 3D model top of case
• [] define and make a demo program, like moving a chess piece from one position to another
• [] define a way to write, store and load “programs” as external files
• [] measure end stops/stalls for each motor; update scorbot.h definitions
• [] Write “clean up” function to position motors near switches so the start up homing process goes faster
• [] add move to end/stall and stop function (good for picking up item with gripper)

Project Log

• January 2026
  • Rough layout of parts on a board - the motors move!
  • modeled and printed controller case. Much easier thinking after just picking a layout. next time would just print base and areas under the ports.
  • Wired up mega, DB-50 connector and 3 L298N’s. My soldering skills are very limited. I would use screw terminal shield for the Arduino Mega next time.
  • motors are working, basically. appear a bit slow, but power supply seems to be working. Desktop power supply reads roughly .5amps when motors are running.
  • the motors seems to need a high PWM value to move at all. I tested voltage across 12v power supply and PWM and appear in range.
  • scorbot.h is where I’m storing definitions and shared functions
  • /helpers/ has working test files
  • helpers/pin_test/pin_test.ino was looking for shorts, etc in the arduino mega pins, due to my clumsy work. surprisingly I got it right on the first try
  • helpers/motor_only_test/motor_only_test.ino just moves the motors back and forth
  • helpers/base_motor_test/base_motor_test.ino is testing for homing and encoders for just the base motor
  • [Scorbot ER-4U][https://www.theoldrobots.com/book45/ER4u_User_Manual.pdf] seems to be essentially the same machine
  • note that Shoulder, Elbow, Wrist Pitch are built in such a way that wrist pitch remains consistent relative as shoulder and elbow move. Moving the shoulder does NOT simply swing the gripper tip relative to the shoulder. Moving the shoulder rotates the elbow to keep the wrist pitch steady. This is cool / confusing. probably needs kinematics
  • Arduino IDE is pretty slow. VS Code extension for arduino has been deprecated. PlatformIO looks too complicated for this project. Arduino Community Edition might work, but CLI, etc are too complicated at this point
  • installed CLANG to VSCode to get linting/formatting
  • MOTOR_ELBOW was a big pain, would not go CCW. turned out the CCW pin (arduinio pin 27) was loose

  • added Queue system to make sequence of actions

  • add move to position
  • add queue of goals, with parallel and sequential steps
  • add all stop with interrupt
  • make ‘home’ the CW clockwise side of the microswitch. there are ~200 encoder steps where the switch is depressed as the arm moves across the button.
  • gripper home is stall when closed
  • wrist pitch and roll movements depend on motors 4-5 working together differential drive
  • shoulder find home
  • write arduino code to get arm to move to home position
  • make replacement microswitch cams
• December 2025
  • modeled scorbot joint cover with microswitch cam.stl, printed and replaced cams. 1 original cam remains
  • ordered L298Ns, Arduino Mega, power supply
• August 2025
  • Got Scorbot ER III discarded by friends at NYC First. No controller or documentation
  • serial number 2090047 model “robot”
  • identified it as scorbot ER iii, found documentation and github projects.
  • Motors can be moved with basic 12v .5A power.
  • Gripper does not move, carefully opening it, seems like encoder case is bent, propellor hitting encoder and LEDs
  • Wrist roll microswitch is hanging off, which may be related.
  • I’m going to run motors on 12v power
  • all 5 microswitch work from switch leads and the pins
  • microswitch cam discs that trigger switches at home point are broken for shoulder, elbow, wrist. for shoulder, using broken pieces, looks like trigger radius is 30mm, clearance is 26-28mm. cup depth is 10mm, center hole dia is 6mm
  • Repaired the Gripper motor and the encoder, which was banged in. microswitch re-attached
  • gripper motor plate uses unusual 3.5mm hex for screws
  • using multimeter on Gripper and base, it seems motor encoders work!
  • Motors do NOT have auto stop switches at ends of rotation. assume they do it in software
  • cams are missing, but based on base, the ‘home’ position, where microswitch is, should be the center of movement.
  • confirmed Gripper encoder works, hand spinning disc. 47 ohm resistor works to LED. LED is infrared, not visible. photoresistor needs 10k pull up to 5v each to pin 0 and 1, where signal is read. (Arduino has this built in)
  • assuming other encoders work, proceeding with buying parts
  • arduino mega has 5v outputs
  • L298N H bridge enable pins can be PWM’d for speed control

Project Goals

This is a messing around, learning project inspired by a free robot arm. The Scorbot ER III is a circa 1995 robot. So simple, maybe even I can work with it!

The goals of the project are to

1. Learn
2. Restore the basic functionality of movement and encoders
3. Design and build an arduino based controller that accepts a joystick-type controller and data input to operate.
4. Enable design students to design and build a microbit based joystick controller
5. Design and build a case

When might I quit this project?

• If motors, or encoders stop working
• If costs go above $200
• If effort goes beyond a few weeks

Project Parts List

• Scorbot ER iii robot arm, without controller or Teaching pendant (~$400-1000)
• Arduino-type Mega board
• D-50 style connector board
• L298N dual h bridge motor controller
• 12v 10 amp power supply

Scorbot Description

Scorbot ER III Manual

Summary

Specification	Value
Mechanical Structure	Vertically articulated
Axes	5 axes plus gripper
Control	8 axes simultaneously
Working Envelope
Axis 1: Base Rotation	310°
Axis 2: Shoulder Rotation	+130° / –35°
Axis 3: Elbow Rotation	±130°
Axis 4: Wrist Pitch	±130°
Axis 5: Wrist Roll	Unlimited
Maximum Working Radius	610 mm (24.4”)
Gripper Opening	75 mm (3”) without rubber pads 65 mm (2.56”) with rubber pads
Maximum Work Load	1 kg (2.2 lb.)
Transmission	Gears, timing belts and lead screw
Actuators	6 DC servo motors with closed-loop control
Feedback	Optical encoders on all axes
Hard Home	Fixed reference position on all axes
Repeatability	±0.5 mm (±0.02”)
Maximum Speed	330 mm/sec. (13”/sec.)
Weight
Robot Arm	11 kg (24 lb.)
Controller	5 kg (11 lb.)

Original power supply

• • 15V, 4A, unregulated, supplies power to the robot motors.
• –15V, 4A, unregulated, supplies power to the robot motors.
• • 5V, 1.5A, regulated, supplies power to the microprocessor, the memory and the logic in the control circuit.
• • 12V, 0.4A, regulated, supplies power to the I/O circuitry outputs, and to the RS232 communications.
• –12V, 0.4A, regulated, supplies power to the RS232 communications.

Motors

• Motors 1,2,3 Pittman GM9413G608 127.7:1 ratio
• Motors 4,5 Pittman GM9413F759 65.5:1 ratio
• Motor 6 Gripper Pittman GM8712F297 19.5:1 ratio

Scorbot Cable connector

The Scorbot cable connector is an DB 50 cable. Connectors and breakout boards that fit are available at Amazon or Ali Express. DB 50 connector Specification DB50 diagram

Here is the pin numbers (looking at the male scorbot cable connector pins)

────────────────────────────────────────────────────────────────────────────────────────────
╲   (1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) (11) (12) (13) (14) (15) (16) (17)   ╱
 ╲    (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (32) (33)     ╱
  ╲ (34) (35) (36) (37) (38) (39) (40) (41) (42) (43) (44) (45) (46) (47) (48) (49) (50) ╱
    ─────────────────────────────────────────────────────────────────────────────────────

SCORBOT ER III WIRING GUIDE

TABLE 1: DB-50 CONNECTOR TO ARDUINO MEGA

DB-50 Pin	Motor	Joint	Signal	Arduino Pin	L298N Board	L298N Input	L298N Output	Notes
1	2	Shoulder	Encoder P0	36
2	1	Base	Encoder P0	34
3	5	Wrist Roll	Encoder P1	43
4	3	Elbow	Encoder P1	39
5	1	Base	Encoder P1	35
6	5	Wrist Roll	Microswitch	50
7	2	Shoulder	Microswitch	47
8	4	Wrist Pitch	Microswitch	49
9	5	Wrist Roll	Encoder LED	5V via 47Ω
10	3	Elbow	Encoder LED	5V via 47Ω
11	1	Base	Encoder LED	5V via 47Ω
12	6	Gripper	Motor +	32	3	3	3
13	5	Wrist Roll	Motor +	30	3	1	1
14	4	Wrist Pitch	Motor +	28	2	3	3
15	3	Elbow	Motor +	26	2	1	1
16	2	Shoulder	Motor +	24	1	3	3
17	1	Base	Motor +	22	1	1	1
18	5	Wrist Roll	Encoder P0	42
19	6	Gripper	Encoder P1	44
20	4	Wrist Pitch	Encoder P1	41
21	2	Shoulder	Encoder P1	37
22	6	Gripper	Microswitch	-				manual says not connected
23	1	Base	Microswitch	46
24	3	Elbow	Microswitch	48
25	6	Gripper	Encoder LED	5V via 47Ω
26	4	Wrist Pitch	Encoder LED	5V via 47Ω
27	2	Shoulder	Encoder LED	5V via 47Ω
28	6	Gripper	Encoder GND	GND
29	5	Wrist Roll	Switch & Encoder GND	GND
30	4	Wrist Pitch	Switch & Encoder GND	GND
31	3	Elbow	Switch & Encoder GND	GND
32	2	Shoulder	Switch & Encoder GND	GND
33	1	Base	Switch & Encoder GND	GND
34	6	Gripper	Encoder P0	45
35	4	Wrist Pitch	Encoder P0	40
36	3	Elbow	Encoder P0	38
37	-	-	-	-
38	-	-	-	-
39	-	-	-	-
40	-	-	-	-
41	-	-	-	-
42	-	-	-	-
43	-	-	-	-
44	-	-	-	-
45	6	Gripper	Motor -	33	3	4	4
46	5	Wrist Roll	Motor -	31	3	2	2
47	4	Wrist Pitch	Motor -	29	2	4	4
48	3	Elbow	Motor -	27	2	2	2
49	2	Shoulder	Motor -	25	1	4	4
50	1	Base	Motor -	23	1	2	2
-	1	Base	PWM (motor speed)	7	1		ENA
-	2	Shoulder	PWM (motor speed)	6	1		ENB
-	3	Elbow	PWM (motor speed)	5	2		ENA
-	4	Wrist Pitch	PWM (motor speed)	4	2		ENB
-	5	Wrist Roll	PWM (motor speed)	3	3		ENA
-	6	Gripper	PWM (motor speed)	2	3		ENB
-	-	-	-	52				Emergency Stop Button

TABLE 2: POWER CONNECTIONS

Component	Connection	Source	Notes
Arduino Mega	12V Vin	Common 12v plug or Barrel Jack	Powers logic
Arduino Mega	GND	Common Ground	Shared with all components
L298N Board 1-3	12V	12V 10A Power Supply	Motor power
L298N Board 1-3	GND	Common Ground	Shared ground
Encoder LEDs (6x)	5V	Arduino 5V via 47Ω resistor	One resistor per encoder
Encoder LEDs GND	GND	DB-50 pins 28-33	Common ground

SERIAL COMMUNICATION

Function	Arduino Pin	Purpose
TX	18	Serial1 - transmit to joystick controller
RX	19	Serial1 - receive from joystick controller

WIRING TIPS

1. Label everything - use labels/tape on wires at both ends
2. Color coding:
   • Red: 12V power
   • Black: GND
   • Yellow/Green: encoders
   • Blue: microswitches
   • Other colors: motor control signals
3. Use a breakout board for the DB-50 connector
4. Bundle by function - keep motor, encoder, and switch wires separated
5. Consider a prototype shield or custom PCB for clean organization

Spec sheets and Manuals

• Scorbot ER III Manual
• Arduino Mega sheet
• Arduino Mega details
• L298N dual H bridge motor controller

CAD

• SCORBOT ER4u Robotic Arm
• L298N dual H bridge motor controller
• DB50 Connector
• DB50 dimensions
• Arduino Mega

Diagrams

Scorbot GitHub Projects

Project Name	Associated Web Pages	Brief Description
Scorbot	• GitHub My Name is Scorbot Scorbot learns to draw”	Arduino MEGA-based controller for Scorbot ER-V with 6-encoder system, custom PCB shield, and Python drawing capabilities. Complete reverse engineering from junkyard condition.
robotic-arm	• Scorbot ER-III Manual	Custom controller replacement for Scorbot-ER III with serial and hard-coded control modes. Arduino-based system with comprehensive reference documentation.
Scorbot	• Author’s Portfolio • CS 287: Advanced Robotics Course	Arduino-based joystick controller for Scorbot robotic arm as cost-effective alternative to expensive original controller. Georgia Tech ECE project.
Scorbot-ER-V-Simulator-Controller	• Hackster.io Project • Arduino Project Hub • Author’s Website • ResearchGate Profile	Professional-grade MATLAB simulation software and hardware controller for Scorbot ER-V+ with PID control, ROS integration, and industrial safety features.
OpenScorbot	• Author: Software Engineer at Casa-Systems	Complete open-source hardware/software controller replacement for SCORBOT ER-IX.
ScorBotToolbox	• USNA Documentation • MATLAB File Exchange • Legacy MTIS Toolbox	MATLAB toolbox for interfacing and simulating Intelitek ScorBot-ER 4U educational robot with comprehensive control and visualization capabilities.
ED-Scorbot	• University Research Page • ROS Simulation	Event-based Scorbot ER-VII platform for neuromorphic research with spike-based controllers, FPGA integration, and spiking neural networks.
scorbot	• Limited documentation available	Scorbot ER-VII implementation with basic functionality.
SCORBOT-ER-VII	• Gazebo simulation files included	Contains simulation files for Scorbot ER-VII in Gazebo robotics simulator environment.
scorbot-simulator	• YouTube Demo • Documentation	Unity-based Scorbot simulator with graphic interface, includes video demonstrations and comprehensive Doxygen documentation. Built with Unity 2017.4.1f1.
openScorbot	• Spanish documentation included	Free controller for Scorbot ER-4U with Python 3.6.9 and Qt 5 Designer GUI.
scorbot	• Processing-based interface documentation	Processing code for mouse-controlled Scorbot-ER V Plus with coordinate mapping system. Future goal: Game of Life with marbles.
scorbot_config	• CraigCode1010.com • Complete SAC project documentation	Configuration files for Scorbot integration with MoveIt motion planning framework. Part of SAC (Scorbot Arm Control) project.
sac_description	• Project Documentation • ROS system topology details	ROS package with URDF descriptions for Southern Adventist University robotic arm simulation, includes Scorbot modeling for Gazebo.
r2d3	• Cross-platform simulator documentation	Free robotic manipulator simulator using Blender and Python, specifically designed for Scorbot ER-V with forward/inverse kinematics and ACL programming support.
sboter4u	• Scorbot ER4U robot configuration using Moveit

Other Robot Arm Projects

• PAROL6
• BCN3D Moveo
• LeRobot
• Faze4-Robotic-arm

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