6-DOF Robot Arm [2026]

Summary and Key Details

A robotic arm with cycloidal and planetary gearboxes, capable of dexterous manipulation and lifting 3 kg while costing under $300
Compliant gripper with a differential wrist mechanism, enable the ability to reliably grasp irregular objects in constrained spaces
Implemented mechanical hard stops, active cooling for electronics, and magnetic a-surface panels for aesthetics

Mechanical Subsystems

The mechanical design consists of 6 main subsystems.

[1] Rotating Base: Belt-Driven Motion, also acts as the electronic enclosure with active cooling using two fans

[2] Cycloidal Gearbox: Utilized in the shoulder and elbow pitch joints, driven by a belt and utilizing the housing as the output

[3] Planetary Gearbox: Provides the 6th DOF (elbow roll) which allows the gripper to pitch sideways instead of vertically

[4] Wrist Differential: Bevel gear differential enabling both wrist articulation and gripper roll

[5] End-Effector: A parallel 4-bar linkage with fin-ray grippers providing compliance to grasp difficult objects

Compliant Gripping

Demonstration of the gripper securely grasping objects across a range of shapes and geometries

Billiard Ball

Mouse

Egg

Pencil

Load Capacity Test

The shoulder and elbow joints demonstrate stable articulation at maximum reach with a load of a 1.5 kg (in the form of my water bottle). Additional testing shows that the actuators can support up to 3 kg, although, the wrist begins to flex and pitch at this extreme.

Overall, the assembly shows a high strength-to-weight ratio, lifting 60% of its total mass in it’s worst-case scenario.

1.5 Kg Shoulder Lift

1.5 Kg Elbow Lift

3 Kg Shoulder Lift