This is exactly how I felt when starting out. I made a conscious decision that I wanted that powerful mid section, not just a line like some fitness model.
The key is heavy weights. Train abs just like you would any other muscle you want to develop. Every ab machine does the trick. All you need is a minimum of 4 sets per day, but you want to go as heavy as you can for a good 15-20 reps per set. Soon, you will be stacking the machines and have the strongest core in the gym. Make sure to train lower back as well. You need to create balance been abs and lower back or else you will get lower back pain. This is a mistake I made. My abs are always showing an 8 pack, even when bulked up, but my weak lower back causes me pain at times.
I've done many ab weight variations. At one time I was doing 500 reps on an ab machine. I made it my cardio. Heavy weight, approximately 20 reps per set, rest 30 seconds, then go again. It took a half hour.