Seems like an accelerator and a small microcontroller (a PIC for example) could do this quite easily. You could then set the angle at which the alarm goes off in the code.

With the light sensor approach you'd need to be careful that the area stayed clean. Otherwise if he covers the sensor with crud it will always indicate that the cane is vertical even when it is not.

With a vibration sensor you'd have to get creative about detecting the impulse event (when the cane falls) and then latch the output so it continues to sound the alarm even after the can has come to a rest.

Seems like an accelerometer and a small microcontroller (a PIC for example) could do this quite easily. You could then set the angle at which the alarm goes off in the code.

With the light sensor approach you'd need to be careful that the area stayed clean. Otherwise if he covers the sensor with crud it will always indicate that the cane is vertical even when it is not.

With a vibration sensor you'd have to get creative about detecting the impulse event (when the cane falls) and then latch the output so it continues to sound the alarm even after the can has come to a rest.