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SCARA Robot Simulation

Explore a Selective Compliance Assembly Robot Arm designed for high-speed pick-and-place, assembly, planar X-Y positioning, vertical Z-axis motion, and trajectory control.

Robotics SCARA Pick & Place Kinematics Stepper
Overview Theory Architecture Simulation Source Code Pinout Examples Downloads

Overview

The SCARA Robot System (scara) is a Selective Compliance Assembly Robot Arm virtual hardware development platform designed for learning, simulating, and validating high-speed pick-and-place, assembly, and 3D trajectory control algorithms.

The SCARA configuration consists of two parallel revolute joints for planar X-Y positioning and one independent linear axis for vertical Z motion.

Joint 1 controls the inner arm rotation θ₁, Joint 2 controls the outer arm rotation θ₂, and Joint 3 provides vertical linear motion through d₃.

Each joint is driven by a dedicated stepper motor driver using ENABLE, DIR, and STEP control signals. HOME and END hardware limit switches provide position boundary detection.

Key Features

  • Two parallel revolute joints for X-Y positioning
  • Independent linear Z-axis motion
  • Three dedicated stepper motor drivers
  • ENABLE, DIR, and STEP control signals
  • HOME and END hardware limit switches
  • Integrated pick-and-place trajectory visualization
  • Integrated simulator and waveform viewer
  • SCARA forward kinematics

SCARA Structure

SCARA Robot Motion Structure
Joint 1
Inner Arm
θ₁
→
Joint 2
Outer Arm
θ₂
→
Toolhead
X / Y
+
Z Axis
d₃

Applications & Use Cases

  • High-speed pick-and-place applications
  • Assembly motion development
  • X-Y planar trajectory planning
  • Vertical Z-axis positioning
  • SCARA forward kinematics experiments
  • Workspace analysis
  • Stepper motor control experiments
  • Educational robotics and automation
SCARA Control Flow
Target Position
→
SCARA Kinematics
→
Joint Control
→
Stepper Drivers
→
Toolhead

Theory

A SCARA robot uses two parallel revolute joints to position the toolhead in the X-Y plane and one independent linear axis to control vertical Z movement.

SCARA Forward Kinematics

X-Y-Z Position
θ₁
+
θ₂
→
X / Y
+
d₃
→
X / Y / Z

X Position 

x = a1 * cos(theta1)
  + a2 * cos(theta1 + theta2);

Y Position 

y = a1 * sin(theta1)
  + a2 * sin(theta1 + theta2);

Z Position 

z = d3;

Architecture

The SCARA system contains two revolute stepper driven joints for planar movement and one linear stepper driven Z axis.

Controller
→
GPIO0
→
Joint 1

GPIO0
→
Joint 2
→
X / Y

GPIO1
→
Z Axis
→
Toolhead

Joint Control Signals

  • ENABLE — Enables the stepper motor driver
  • DIR — Controls motor direction
  • STEP — Generates active-high step pulses
  • HOME — Detects the home position
  • END — Detects the end limit

Simulation

Run the SCARA robot simulation and observe X-Y planar movement, vertical Z-axis motion, pick-and-place trajectories, joint movement, and workspace limits.

The integrated simulator and waveform viewer allow the control signals and robotic motion to be analyzed together.

Launch Simulation

Source Code

Example GPIO configuration for the SCARA robotic system. 

// GPIO0: Outputs on bits 0,1,2,5,6,7
// Inputs on bits 3,4

WRITE_REGISTER(0x40000000, 0xE7);


// GPIO1: Outputs on bits 2,3,4
// Inputs on bits 0,1,5,6

WRITE_REGISTER(0x40000400, 0x1C);

SCARA Forward Kinematics 

x = a1 * cos(theta1)
  + a2 * cos(theta1 + theta2);

y = a1 * sin(theta1)
  + a2 * sin(theta1 + theta2);

z = d3;

Pinout

GPIO register mapping for the two revolute joints and the vertical Z-axis.

GPIO0

Bit 0
J1_ENABLE
Bit 1
J1_DIR
Bit 2
J1_STEP
Bit 3
J1_HOME

Bit 4
J1_END
Bit 5
J2_ENABLE
Bit 6
J2_DIR
Bit 7
J2_STEP

GPIO1

Bit 0
J2_HOME
Bit 1
J2_END
Bit 2
Z_ENABLE
Bit 3
Z_DIR

Bit 4
Z_STEP
Bit 5
Z_HOME
Bit 6
Z_END
Bit 7
Unused

Register Addresses

GPIO0 MODE
0x40000000
GPIO0 IN
0x40000004
GPIO0 OUT
0x40000008

GPIO1 MODE
0x40000400
GPIO1 IN
0x40000404
GPIO1 OUT
0x40000408

Examples

Example exercises for the SCARA robotic system.

  • Move Joint 1 through its -135° to +135° range
  • Move Joint 2 through its -150° to +150° range
  • Control vertical Z-axis movement
  • Perform joint homing using HOME switches
  • Detect END limit switch positions
  • Move the toolhead to a target X/Y position
  • Move the toolhead to a target Z height
  • Perform pick-and-place trajectories
  • Analyze the SCARA workspace

Downloads

Download SCARA simulation files, source code, documentation, register configuration, and waveform files.

Download Files