By this, I am assuming you mean that the clamp tips the goal back toward the robot.
This is possible, although not easy. My team was able to design a system that would do this, and we did add it to our robot for a short time, before changing out for a different design. If you plan on doing something like this, keep in mind what motions are actually necessary, and how they are linked.
Assuming a clamp that consists of a fixed portion and moving latch, where the whole clamp has to rotate, the motions are something like this: the direction that the clamp spins around its fulcrum is opposite the direction the whole device needs to rotate to tip the goal, and the clamp must close before the goal can tip to go up, but the reverse must happen to set the goal down gently. So ‘latch, then tip’ going up; and ‘tip, then latch’ going down. How could you go about doing this?
Further explanation
If we assume that motion has to get transfered to the latch from the outside (the part that everything rotates around, and that is firmly attached to the robot), the only point that stays in the same relative space is the pivot point that the clamp rotates around. By using an axle (instead of a screw) joint there, motion can be transferred from “outside” the clamp to “inside” the clamp. However, the latch has to move at a different time than the rest of the clamp, so the axle can not be firmly attached to the clamp (the axle has to be able to rotate in relation to the clamp). If we attach the latch directly to the axle, it will open and close fine, but the clamp will not tip from any input. If you add a hard stop to the latch to restrict its downward movement (so it does not just spin all the way around), the clamp would tip, but not in the direction we want. Remembering back from the description of how the parts have to move, we know the latch has to rotate in the opposite direction as the whole clamp. Two gears will reverse the direction of rotation, so we need to add them in after the motion reaches the clamp, but before it reaches the latch. Adding gears that rotate around the main structure of the clamp, but are only attached to the main axle and the latch will do the trick. Now, when the latch reaches its “closed” position, further rotational input (still in the same direction) will cause the clamp to tip back.
The only thing left to do is to make sure the latch moves before the clamp does, but that can be accomplished by making it easier to rotate the smaller latch rather than the larger clamp assembly. Sometimes, this is already the case because the difference in mass (more specifically the moment of inertia) between the two moving parts causes the lighter latch to move easier than the heavier clamp, but if the parts do not move in the correct order, adding a rubber band to hold the clamp in its “not tipped” position will do the trick. Be careful, however, because this rubber band is working against the motor, requiring even more force.
I can find a picture if that would be more helpful than the wall of text above.
A word of warning if you choose to go down this route: A lot of torque is put on the system. To make the clamp work with minimal overheating, we used a red motor with an external gear reduction of 27, but the motor still got warm after a lot of use. Getting this kind of torque means the system is painfully slow (one of the reasons why we scrapped the idea), so do be aware of that. Motors are also designed to spin, so having them hold in place against a large amount of torque is not doing the motor any favors. On the other hand, pneumatics are great for holding one position for extended periods of time, so if it is an option, I would suggest using something like 2775J’s design that uses pneumatics to accomplish the task more quickly (and in my opinion, more efficiently) than a motor would.