robodatech.Limits and reach
Keep each joint inside its allowed range and avoid self-collision. Close to singular configurations, a small tool movement may require large joint speeds.
Actuators
Move a joint. Position a tool.
Explore joint space, tool space, gearing, inverse kinematics, and trajectory control in a robot arm.
Try it yourselfChange an input.
Change an input.
See what follows.
A simplified learning model. Values describe the model, not a connected robot.
A joint angle is only part of the story.
Joint space describes the angles or extensions of individual axes. Task space describes the tool position and orientation. Forward kinematics calculates a tool pose from joint positions. Inverse kinematics asks which joint positions reach a desired pose; some poses are unreachable, and others have multiple solutions.
Start with a two-link arm
x = L1 cos θ1 + L2 cos(θ1 + θ2)
y = L1 sin θ1 + L2 sin(θ1 + θ2)
y = L1 sin θ1 + L2 sin(θ1 + θ2)
For two 0.10 m links, θ1 = 0 and θ2 = 90° place the tool at (0.10, 0.10) m in the ideal planar model. Link lengths are measured between joint axes. Tool offsets and mechanical flex must be included for useful accuracy.
Plan the move
Smooth trajectories
Interpolate position with speed and acceleration limits. Jumping directly between distant angle commands can cause high current, vibration, and unstable loads.
Feedback
A positional hobby servo has an internal loop, but usually does not report actual position to your program. Smart servos or external encoders let the controller verify motion.
Use the angle experiment
The diagram shows the requested angle of an ideal 180° positional servo. Real pulse width, travel range, and direction depend on the servo and linkage. Continuous-rotation servos interpret the command as speed/direction instead of an absolute angle. Calibrate with the linkage disconnected and never force a mechanism against a stop.
Go to the source
Manufacturer and project documentation. Reviewed 20 September 2026; check your exact board revision and software release.