The open-close-open-step-sweep drill is a judo drill that I use to improve efficiency in my aikido training. In this drill, you open your hip by pointing your toes on one foot outward, away from your body. Then close your hips by moving your other leg so that the toes on each foot are facing one another. Open the other hip again, and sweep with the opposite foot. Efficient movement is extremely important in aikido, because it allows you to quickly respond to any situation. Moving efficiently allows you to cut out “beats” or “steps”. The effect is that you can respond much more quickly without actually moving faster.
The open-close of your hips in this drill creates a coil effect. This helps send you in the direction you need to be going. Since the coil helps give you an extra “boost”, you are expending less energy. Once you understand how this drill works, you can practice it in your walking kata, if your dojo does this. If not, you can practice this on your own to become more efficient in your movements and improve your aikido overall.