The following description is of an exercise. It is not combat, nor even a simulation of combat. It's a simple study of vectors working in combination.
This is a two-person exercise. You'll need a jo, or similar prop.
One person holds the jo at one end, using one or two hands, and positioned to sight along the length of the jo as if preparing to thrust.
The second person stands near the other end, also holding, but with only one hand, and positioned to the side looking across the axis.
The first person moves forward along the axis of the stick. The second person moves backward, at 90 degrees from the orientation of the stick.
Call the first person the "actuator." This person simply moves forward in the direction the jo is pointing, keeping the far end aligned with the center of their own body.
Call the second person the "sensor." This person only moves in response to the actuator, and will immediately stop if the actuator stops. The sensor must endeavor to respond immediately to any movement without hesitation or resistance. Though looking cross-axis to the jo, the sensor will also keep the tip of the jo aligned with the center of their own body.
What happens? Each component is (or should be) moving in a straight line. These lines however, are orthogonal to one another, and so the net result is that the system turns. If the sensor is properly attuned to the impulse of the actuator, and the speeds of each mechanism are matched, the system will trace out an approximation of a circle.
Play around with this and see what you can notice. It's important to realize that the system will revolve around a central area, but neither of the players occupies that center.
Soon you'll get bored, so mix it up a bit. Allow the sensor to walk forward instead of backward, or can alternate between the two. Let the actuator smoothly vary the pace, and randomly start and stop.
Next, we instruct the actuator to try to aim the jo into the center line of the sensor, while still following the axis of the stick. This will be difficult, as an arc with a radius roughly equal to the size of the jo must be traversed in order to get the alignment right. The sensor can easily prevent this by simply adhering to protocol.
However, it's a bit more fun if the sensor occasionally allows this and then quickly changes from one side of the jo to the other, changing hands if it seems useful. The actuator still has to work hard at the attempt.
Now eliminate the jo. The actuator extends a hand or a fist in place of the jo. The sensor places a hand on the back of the actuator's hand. Repeat the progression above, but note the sense of accelerated pace that the closer proximity allows. Experiment with different speeds, so long as things stay safe and productive for exploration and learning.
As you learn the dance from both sides, you may start to see the opportunities arising to execute a throw or a controlling art. Don't be too quick to seize each chance, but loosen up the protocol a bit to allow yourself to express your aikido more.
It's not combat. It's just an exercise.
But it has the potential to turn into a good simulation of combat, so when the time is right, take it there.
Still Point Aikido Systems
Austin TX, USA