Gripper+PING

oss6000

I'm thinking of getting the Gripper kit + the PING kit (both the ultrasonic sensor and the servo) for my Boe Bot (with BS2)...... so my question is would that be ok or would I exceed the power of the 6 v battery pack....

thank u

MSDTech

Power won't be as much a problem as the mechanical interferance. Both devices mount on the front of the BOE-BOT using the same mounting holes. You are going to have to make some serious modifications to use both devices. The BOE-BOT will also tend to be front heavy, so you are going to need to add some additional weight to the rear, like a·higher capacity (and heavier)·battery pack.
I'm in the process of modifing a BOE-BOT to use both the Gripper and a Ping. I'll post some pictures of the system when I get it all put together and working.

oss6000

thnx MSDTech.....looking forward for the pictures

MSDTech

I've got the·third build of the BOE-BOT with the Ping and the Gripper installed and decided to post a few photos of the unit. This is a classic example of "scope creep". It started out as a simple project and each time I analyzed the data on its performance, the thing got more complex.

The fist photo is the first build.·I·found the BOE-BOT wheels had no traction on the carpeting, limiting it to running in the kitchen or bathroom (and it kept heading for the door). The extension to the Ping Bracket was for the infrared detectors, which are mounted under the bracket. This allow it to at least scan for objects close to the bot.

The second photo is where I added the Tank Tread Kit to try to improve the performance on the carpeting, but·it had a habit throwing treads on the the high pile carpeting in my house. It worked in a roaming mode but was still·having problems with sensing close objects due to the height of the ping. It has to be set high to clear the control rods for the gripper.

The third photo is the current configuration. I added a set of the VEX Robotics treads. They are a harder tread and work well in the carpet. I also added a Crustcrawler S3 instrument head. I can now both pan and tilt, so it can look down for obsticles. I also threw on a 2.4 Ghz security camera. At least I can now watch where it is looking and compare that the the debugging telemetry it's sending back to my computer.

Once I get the code in a better shape I'll post a complete write up. I'm shooting for solid roaming code to be completed when school starts this fall. I can mount a poster on it announcing the extra-curricular micorprosser/robotics club I'm starting and it should generate some interest.


Post Edited (MSDTech) : 6/10/2008 3:32:27 AM GMT

CJW

Hi MSDN TEch,

I would like to know how you modify the Ping. As I doing similar thing, using Gripper+Ping at the moment. Can you show me step by step. Thank you

Best Regards,
James

MSDTech

James,

There is no single step by step solution. I've gone through multiple configurations with the two devices. The problem is that if you are working with the BOE-BOT chasis, both devices mount in the same location. The servo for the ping bracket is attached at the same spot where the base for the gripper attaches. Also the gripper has an acutator rod that runs the entire length of the chasis from the rear (where the gripper servo is attached) to the front. You will need to do some metal work to create an alternate mounting scheme. If you look at the first picture I posted, I added an intermediate panel to the BOE-BOT and mounted the ping servo on risers coming up from that. This gave clearance for the gripper, but made the entire unit top heavy and it was unstable. I've tried several different configurations since then but they all ended up too tall and narrow. One other problem with the PING mounted high·is that it has trouble·detecting objects close the the front of the robot.

I finally gave up on the ping bracket and BOE-BOT chasis and built a custom chasis with the Crust Crawler pan-tilt sensor·head. I also added a second servo to activate the gripper paddles - one for each paddle, which allows me to set the sensor head lower on the chasis.·I've attached a photo of the chasis. You can see the servo for the right gripper attached to a rod that just passes between the pan servo and the mounting posts. The current configuration of the sensor head has both the PING and a Sharp IR rangefinder attached. It also has a small security camera attached to allow me to see what the robot is "seeing". With two servos attached to the gripper paddles, it makes it a little more complex to grasp an item, but it does allow the robot to wave a single gripper.

I also considered mounting the PING bracket on the back of the BOE-BOT chasis behind the servo for the Grippers. That would have kept the height down, but I'm not sure how well the PING would have been able to work in that location.

Rick

CJW

hi,

I using a normal boe bot.