Robotics you can drag around

Two wheels, two motors, and the one equation underneath skid steer, Ackermann steering and every trailer that ever jackknifed.

Drive a mecanum chassis, watch the four motor powers, and find out why mounting the rollers wrong costs a whole degree of freedom.

Four numbers per joint describe an entire arm. Type a table in and watch it appear.

Every reachable point has two arm configurations, and choosing between them is a real decision.

Three gains, each one a trade. Tune a joint and watch the response change.

Grow every obstacle by the robot's own shape and the robot becomes a point. Every planner after that is simpler.

Dijkstra plus an estimate of the distance remaining, and far less of the map examined.

Every cell one step away, then every cell two steps away. The first route it finds is the shortest.

Change the queue to a stack and every guarantee disappears.

One neuron computes a weighted sum and thresholds it, which draws one straight line. Everything else follows from what that line cannot do.

A robot learns to pick and place by filling in a table of numbers, one cell at a time.

Bigger gears turn slower and push harder. Change the tooth counts and watch the train work it out.