An arm needs stiff, low-backlash joints near the base and lighter joints toward the tool. Here is what each joint needs and where to find it.
Joints
- Shoulder and elbow carry the arm and payload at full reach: harmonic joint modules or high-ratio and cycloidal joints.
- Wrist joints trade torque for low weight and size: see robot arm and cobot joints.
- Custom joints start from frameless torque motors and a reducer.
- Complete arms: robot arms and cobots. Financing is available: net terms or monthly payments.
Around the joints
- Encoders on the output side for absolute joint position, brakes so the arm holds when power drops, and motor drivers.
- For the tool: electric grippers and dexterous hands.
Sizing
Use the arm mode of the joint torque calculator for each joint from the base out, then compare reducers in Harmonic vs planetary vs cycloidal reducers and check heat in How to size a robot joint motor.
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