May 2009

Grab-n-Go is a NXTCAM controlled vision robot that can locate and pick up a red ball. It combines the drive motor assembly from the 8275 Bulldozer, the track supports from the 8294 Excavator, and Paul Tingey’s Clamp-n-Lift.

After building Wall-E I knew that I had to raise the Power Function motors up from the ground as they caught on obstacles on the floor. I tried a number of designs before stopping to see that the Bulldozer was the best way by far to mount a PF large motor for a tracked drive. It didn’t take me long to mount a track support from Queboid, which was derived from the 8294 Excavator model. So far so good; I have a drive and track assembly that is robust, rigid and proven to work.

To lift a ball I tried build a number of arm assemblies, none of which were satisfactory. I re-visited Paul Tingey’s Clamp-n-Lift design, where a single motor closes the grabber and then causes the grabber to lift the ball. I wanted to mount the NXTCAM as close to the plane of the ball as possible, which implied that I had to modify the Clamp-n-Lift design. After a number of experiments I mounted a smaller Clamp-n-Lift on the end of two parallels lifting arms, mated to a Medium PF motor driving a worm gear. The NXTCAM fit snugly between the lifting arms, and was only obscured when the arm was lowered. The best part was the Clamp-n-Lift would close when the arm lifted, and open as it lowered, which saved me a motor!

The PF motors are controlled via a Mindsensors NRLink mounted at the top of the robot. I mounted a front-facing Mindsensors DROD-Nx to detect obstacles.

Pictures