How to Do a Pendulum Sweep
The pendulum sweep has been a staple of Brazilian Jiu Jitsu, both in the realm of competitions and self defense, for several decades now. The fundamental principles of this sweep can be applied across a wide range of positions, as we'll see here. Start with the closed guard versions, and work your way outward and upward in complexity.
The Fundamental Sweep
Start by controlling your partner's right sleeve with your left hand while they're in your closed guard. As they move to stand up, they make a crucial mistake by lifting their opposite (left) leg up, leaving them vulnerable to the pendulum sweep. Hug your partner's leg with your right arm (don't grip, just use the underhooking arm to pivot to a right angle). Next, kick your left leg out to build up momentum, and as soon as you reach the apex of the swing, just chop back (similar in nature to a scissor sweep). Use the momentum of your bottom leg to help kick upward and across against your partner's armpit. Go straight to mount.
One of the great elements of the pendulum sweep is that you're making yourself perpendicular with your partner, which means other opportunities immediately open up (if jiu jitsu is about any two key factors, it's range and angle of attack). Note that you can finish the armlock either from the guard or from the armbar finish position, and this is going to depend on how effective your initial sweep attempt is. It should be relatively easy to transition to the armbar if they're fighting hard enough not to be swept.
Once you hit the right angle, the sky opens up in terms of opportunities. Another such option is the omoplata. Note that when you pivot to the side, your near-side leg is able to transition easily in front of your partner's face, easily allowing a fundamental omoplata entry.
Pants Grip Variation
This move is somewhere in between the classic pendulum sweep and the updated Xande sweep. One benefit here is that your partner doesn't have to start standing up at all in order for you to hit the sweep, and you can simply reach outside of your partner's knee and grip the pants in order to get a similar effect. Another advantage here is that you can keep the pants grip once you reach the top, virtually ensuring that you will end up on top in mount. Further, when you start the movement from guard, you can watch your partner's movement (even better, you can feel it), and just wait for their weight to shift.
Arm Drag Pendulum
The closed guard arm drag position is one of my personal favorites. Start by cross gripping their right sleeve (with your right hand), and pull their arm across. Solidify this by gripping their far armpit with your left hand, making pulling that arm free considerably more difficult. Next, wait for them to start driving in to you (if they don't, you can just go to their back instead). Once they drive in, they are primed for a simple pendulum sweep.
Closed or Open Guard?
Pendulum sweeps are fascinating and beautiful, and likely one of the first moves you gravitate toward from closed guard. It's certainly one of the areas in which I was relatively effective early on, and it stuck with me throughout my career. The interesting thing to watch was how much the position evolved over these years, and continues to evolve today. There are numerous applications for the pendulum motion in BJJ, and we've only glanced at a rich handful of options from one place (closed guard). As always, let me know if these techniques work well for you!