THEORY: Encoders (optical, magnetic, capacitive)
DEVICES: rotary optical encoder
HANDS-ON: connect an encoder to a DC gear motor (from mini-bot kits)
Observe pulses with oscilloscope or LED
Connect encoder to Arduino and maintain speed across range of loads by varying PWM in response to encoder output
THEORY: current measurement (revisit ohms law, use of sense resistor)
DEVICES: current sense resistor
HANDS-ON: measure load on motor by monitoring current through sense resistor; implement stall protection if current exceeds threshold.