Vertical Drag

Vertical drag mode complements horizontal drag by mapping mouse movements to the YZ (side-view) plane. The arm tip moves up/down and left/right while the forward reach stays fixed.

How It Works

The interface maps 2D mouse coordinates to the arm’s YZ plane. The X position (forward reach) stays constant while Y and Z track the mouse.

graph LR
    A[Mouse XY] --> B[Scale to Workspace]
    B --> C[Set X = constant]
    C --> D["T:104 XYZT Command"]
    D --> E[Arm Moves in YZ Plane]

Use Cases

Vertical drag is particularly useful for:

• Shelf operations: Reach to a fixed depth, then navigate between shelf levels
• Wall-mounted tasks: Move the arm along a vertical surface
• Stacking: Maintain constant reach while varying height and lateral position

Python GUI Implementation

Similar to horizontal drag, but mapping the canvas to Y and Z axes:

import tkinter as tk
import requests
import json

ARM_IP = "192.168.4.1"
X_REACH = 235  # Fixed forward reach in mm

def send_position(y, z):
    cmd = {"T": 104, "x": X_REACH, "y": y, "z": z, "t": 3.14, "spd": 0.5}
    try:
        requests.get(f"http://{ARM_IP}/js?json={json.dumps(cmd)}", timeout=0.5)
    except requests.exceptions.Timeout:
        pass

def on_drag(event):
    # Canvas X → Arm Y (lateral), Canvas Y → Arm Z (height)
    y = (event.x - 200) * 1.0
    z = (400 - event.y) * 0.75  # Scale to 0-300mm height range
    send_position(y, z)

root = tk.Tk()
root.title("RoArm-M2-S Vertical Drag")

canvas = tk.Canvas(root, width=400, height=400, bg="#1c1917")
canvas.pack()

for i in range(0, 401, 50):
    canvas.create_line(i, 0, i, 400, fill="#292524")
    canvas.create_line(0, i, 400, i, fill="#292524")

canvas.create_line(200, 0, 200, 400, fill="#d97706", width=1)
canvas.create_line(0, 300, 400, 300, fill="#d97706", width=1)  # Ground level

canvas.bind("<B1-Motion>", on_drag)
root.mainloop()

Combining Horizontal and Vertical

You can run both interfaces simultaneously — one window controls XY position, another controls YZ. The last-received command wins, so alternate between them rather than dragging both at once.

A more advanced approach: use horizontal drag for coarse positioning, then switch to vertical drag for height adjustment. The web interface supports toggling between both modes.

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Vertical drag concept from the Waveshare Wiki.