LEARNING PATH 03 · 25 GUIDES
SCARA robots
Understand two-link geometry, build motion profiles and commission a small pick-and-place system.
Start with: Trigonometry, radians and basic Python. Use a simulator before any motor test; physical axes need travel limits, guarding and an appropriate stop system.
The planar examples omit structural flexibility, full three-dimensional collisions and many drive limits. A SCARA is not automatically collaborative. Keep people outside the operating envelope and validate the actual machine before powered testing.
From foundations to a working test
25 practical guidesUnderstand the four axes of a SCARA robot
A common SCARA combines two horizontal rotary joints, a vertical axis and a tool-rotation axis. This arrangement suits planar transfer and insertion…
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Choose SCARA link lengths from the required workspace
Two link lengths define an ideal annular planar workspace. Start with the required inner and outer radii, then leave room for joint limits, fixtures and…
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Calculate SCARA forward kinematics by hand
Forward kinematics converts measured joint angles into the tool’s planar position. Derive this small model before debugging a controller: it gives an…
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Solve two-link SCARA inverse kinematics
Inverse kinematics finds joint angles for a requested x-y target. A planar two-link arm often has two solutions. The calculation must reject unreachable…
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Keep a continuous SCARA elbow branch along a path
Choosing an inverse-kinematics solution independently at every point can make the elbow flip. Track the previous joint state and select a nearby valid…
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Build the planar SCARA Jacobian
The Jacobian connects small joint movements to small tool movements. It explains velocity limits, force transmission and singularities. Differentiate the…
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Recognize SCARA singularities before commanding motion
At full extension or a folded alignment, the two-link arm loses an independent instantaneous motion direction. Inverse kinematics may still return a…
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Convert a desired SCARA tool velocity into joint speeds
A modest Cartesian speed can require very different joint speeds at different poses. Solve the local Jacobian equation, then check the result against each…
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Estimate SCARA joint torque from a planar tool force
A tool force becomes joint torque through the robot geometry. The Jacobian transpose gives a useful static relationship. It excludes acceleration,…
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Apply joint limits to a SCARA workspace map
An ideal workspace annulus includes points that may be excluded by real joint stops. Sample the permitted joint ranges and map them through forward…
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Convert stepper pulses into SCARA joint angle
A stepper drive receives pulses, while the kinematic model uses angles. Keep the conversion explicit, including microstep setting and gear reduction.…
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Why microstepping is not the same as positioning accuracy
Microstepping increases commanded angular resolution and can improve smoothness. The actual shaft position also depends on load, torque ripple, friction…
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Select a belt reduction for a SCARA joint
A belt reduction trades output speed for torque and nominal angular resolution. It also changes reflected inertia and mechanical behavior. Start with…
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Estimate how belt compliance affects SCARA endpoint error
A compliant transmission twists under load, causing position error even when the motor encoder reaches its target. A rotational stiffness model helps…
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Measure SCARA homing repeatability
Homing establishes a reference after startup, but switch activation can vary with speed, mechanics and signal filtering. Measure the final reference…
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Measure backlash by approaching a SCARA target from both sides
Lost motion after reversing direction can make a robot accurate from one approach and wrong from another. Compare opposing approaches at the same target…
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Convert lead-screw rotation into SCARA vertical travel
The vertical axis converts motor rotation into linear movement. Use screw lead, not thread pitch, when multiple starts are present. An incorrect…
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Estimate SCARA vertical-axis lifting torque
A screw-driven lift requires torque to raise its load and accelerate it. Include the complete moving assembly, then account for screw efficiency and…
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Keep SCARA tool yaw constant while the arm moves
If the tool must keep a label or connector aligned, the wrist has to compensate for shoulder and elbow rotation. Compute orientation from the complete…
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Design a trapezoidal velocity profile for a SCARA axis
A trapezoidal profile accelerates, cruises and decelerates. It is easy to calculate and useful as a baseline, although a real controller may smooth…
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Use cubic time scaling for a smooth SCARA demonstration
A cubic time law makes joint velocity start and end at zero. It is useful for simulation and low-level understanding of trajectory generation. It does not…
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Make a SCARA tool follow a straight Cartesian line
Interpolating joint angles does not generally make the tool move in a straight line. Define the line in Cartesian coordinates, solve inverse kinematics…
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Generate a SCARA circular path with chord-error control
A circle approximated by line segments deviates between sample points. Choose sampling from permitted geometric error, then check kinematics and timing.…
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Calibrate SCARA link lengths using independent reference points
Nominal CAD dimensions may differ from effective joint-to-joint lengths. Calibration should use multiple configurations so link-length errors can be…
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Commission a SCARA pen-plotter prototype in stages
A pen plotter is a useful low-force demonstration of geometry, but the moving arm still presents hazards. Separate offline kinematic verification,…
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