Dobot Magician Lite — Pick & Place Automation

RAS 545 · Robotic and Autonomous Systems Lab 2 · Arizona State University · Fall 2025

Two end-effector experiments (suction cup + gripper) automating a 4-block pick-and-place cycle with full forward and reverse passes using the pydobot library.

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Demo

Lab 2.1 — Suction Cup	Lab 2.2 — Gripper
device.suck(True/False)	device.grip(True/False)

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Overview

The Dobot Magician Lite (Serial: DT15-2311-1673) was programmed to move 4 labeled blocks (A–D) between two pallets using two different end effectors. Each script executes a forward pass (Pick → Drop) followed by a reverse pass (Drop → Pick), returning all blocks to their original positions.

Both scripts use a hover-descend-actuate-lift motion pattern with a configurable HOVER_Z offset to prevent collisions during transit.

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Repository Structure

.
├── lab2_1.py                          # Suction cup pick-and-place
├── lab2_2.py                          # Gripper pick-and-place
├── lab_2_vishal_RAS_experiment.pdf    # Full lab report with results & analysis
└── README.md

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Technical Details

Motion Pattern (both scripts)

Home → Hover above pick → Descend → Actuate end effector → Lift → 
Hover above drop → Descend → Release → Lift → Home

Coordinate System

All positions are defined as (X, Y, Z, R) in millimeters relative to the robot base frame.

Pick positions (Pallet 1):

Block	X (mm)	Y (mm)	Z (mm)
A	237.41	−67.42	−45.77
B	230.60	−8.63	−45.49
C	296.60	−60.63	−49.27
D	289.58	−3.57	−48.35

Drop positions (Pallet 2):

Block	X (mm)	Y (mm)	Z (mm)
A	222.19	75.39	−46.31
B	219.04	135.19	−46.46
C	281.51	79.77	−46.59
D	279.33	137.88	−49.13

Key Parameters

Parameter	Lab 2.1 (Suction)	Lab 2.2 (Gripper)
End effector	Suction cup	3-finger rubber gripper
Speed	200, 200	20, 20
Hover offset (HOVER_Z)	40 mm	40 mm
Dwell time	1.0 s	1.0 s
Motion mode	MOVJ_XYZ	MOVJ_XYZ
Actuation API	device.suck()	device.grip()

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End Effector Comparison

Criteria	Suction Cup	Gripper
Surface requirement	Smooth, flat, clean	Any surface
Mechanism	Vacuum adhesion	3-finger mechanical grasp
Object weight limit	Low–medium	Medium–high
Reliability on plastic blocks	Good	Better
Industrial use case	Electronics, packaging	Varied shapes, warehouse

Conclusion: The gripper proved more reliable for the plastic foam blocks used in this lab. The suction cup required precise Z-calibration and smooth block surfaces to maintain consistent vacuum.

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Setup & Usage

Requirements

pip install pydobot

Ensure the Dobot USB driver is installed and no other application (e.g. DobotStudio) is holding the COM port.

Hardware

• Robot: Dobot Magician Lite
• Connection: USB → COM5 (update PORT constant if different)
• End effectors: Suction cup (Lab 2.1), Pneumatic gripper (Lab 2.2)

Run

# Lab 2.1 — Suction cup
python lab2_1.py

# Lab 2.2 — Gripper
python lab2_2.py

The robot will home first, then execute the full forward + reverse block sequence automatically. Press Ctrl+C to interrupt safely — the finally block closes the serial connection cleanly.

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Lessons Learned

• Time delays (time.sleep()) after actuating the end effector are critical — without them the suction cup releases before the block is lifted
• Varying HOVER_Z directly controls cycle time; too low risks collision, too high wastes time
• Z-values must be individually calibrated per block position — surface height variation of even 3–4 mm causes missed picks
• Gripper orientation (rotation R) matters for consistent block grasps — blocks must be square to the gripper jaw axis

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Course Info

• Course: RAS 545 — Robotic and Autonomous Systems Lab
• Instructor: Prof. Mostafa Yourdkhani
• Lab Charge: Mohammad Nasr · Rajesh S Aouti
• University: Arizona State University, Tempe AZ
• Semester: Fall 2025
• Grade: 10 / 10