We’ve made great progress in the cleaning up of PR2Lite into its final configuration.
- Replacing the old desktop-based computer with its converter with a laptop went a long way to clean up the wiring.
- We added a shelf for the laptop above the microcontrollers for the linear actuator and wheel pids.
- The wires now go up in a channel cut into the shelves per its original design.
- In the shelf above the laptop, we put the new DC to AC converter, all the AC adapters (e.g., for the neato the usb hubs, the dynamixels, the kinect), and two powered USB3 Hubs for all the USB-based controllers.
- the next shelf up has three 12v SLA to power the DC to AC adapters. It also holds the joystick.
- The top shelf has the neato board and some battery voltage level detectors.
- The dynamixel CM-5 and USB2Dynamixel were moved down within the moving outer torso.
- The Linear actuator holders for the torso up/down were re-glued.
- Courtesy of excellent Robotis customer service, our new MX-106/MX-64/Velo gripper arm is operational again.
We are currently upgrading the encoders for the wheels and continue to improve the mobility of the base.
Pictures of PR2Lite, which now doesn’t need to be plugged into an outlet to run!
PR2Lite’s arm moving (It planned out it’s movements — see the laptop screen)
Here’s an old video of our wheel mechanism that until now, remained off of the internet. It’s from a long while back, so please ignore my silly voice.
PR2Lite has completed its initial migration to Hydro and Moveit! with the help of its new laptop.
The migration after the fix for the mimic joints was installed went smoothly. The integrated support of moveit with the higher level planner, the lower level planner, rviz, fake joints, mimic joints, the setup assistant, the configuration files, and more makes support for non-PR2 robots much simpler than the older arm navigation in ROS Electric. Having already gone through the learning pains and building some of the necessary infrastructure to get a working arm-navigation from ROS Electric definitely helped the migration go well. Some of the old PR2Lite custom configuration files and PR2Lite controllers overlap the newly provided generic functionality provided by Moveit, but it doesn’t seem to cause any operational issues and provides some improved flexibility at a cost of increased configuration complexity. Including the torso lift as part of PR2Lite’s arm navigation results in much better plans.
In summary, we wish Moveit! had been around a few years ago.
The pr2lite_moveit_config and moveit_pr2lite code for arm navigation has been uploaded to git_hub:
We are now beginning a phase of cleaning up of PR2Lite:
- replace the old desktop-based computer with its cumbersome DC-AC converter with the nicer laptop
- We currently rely mostly on a tethered robot. We’re about to change that to improve pr2lite mobility. Unlike the current configuration, we’ll make it easy to be able between switch from battery power and tethered power. To accomplish this, we’ll use a new DC-AC converter to power the following components that need either a wall-adapter or additional power:
- the Laptop power adapter
- the USB power for the hikuyo lidar
- powered USB3/USB2 hubs for the IMU and microtrollers
- the power chord of the kinect
- the power for the Dynamixel servos
- the power adapter for the neato lidar
- wireless hub
- The wheels and the linear actuators will have their own dedicated batteries.
- add low-battery alarms to avoid silent errors with our linear actuator and wheel drivers
- clean up the wire mess.
- continue to improve the reliability of the microcontrollers
- upgrade the resolution of the wheel encoders
In parallel, we’ll continue to test 2D navigation (hydro version not yet checked in), the new MX-based arm, and more.
The Velo Gripper wrist is nearly complete! Here is a separate update for just the Velo Gripper wrist.
We have also detached the right arm to make new drill holes to accommodate the MX64 and MX106 servos we’re putting in. The shoulder’s MX64 servo (not pictured) fit in with minimal effort, which is nice.
We were having troubles with the long cables that controlled the linear actuators and wheels; the signals would get too many collisions because the wires were too long. Frank had trouble converting the cables into smaller cables, DB9 connectors, and RS485 signals originally, but has since gotten them to work. Version 1 did not work, but Version 2 did. Both are pictured below.
We also have a new Ubuntu System 76 laptop (quadcore i7 with SSD) which will replace our current computer in the robot, and open up some space. We’re also moving to the Hydro ROS release and moveit! arm control sometime in the future. Here’s a picture of the laptop:
Here are three pictures of PR2Lite at Maker Faire 2013 that Melonee Wise took! This was when we had PR2Lite attempt to play chess with Michael Ferguson’s Maxwell.
Thanks Melonee! If you want to check out some of her other Maker Faire pictures, here’s the link!
We’ve made a large step in our integration with Willow Garage’s Velo2G Gripper. I completed my design on AutoDesk Inventor 2013 of the wrist, which controls the Velo Gripper and rotates. I also designed other parts which will complete our upgraded lower arm. I had to change holes and parts to accommodate for larger servos like the MX106 and MX64. Here is a screenshot of the final drawing.
We ordered the pieces to be cut from Mr. Plastics in San Leandro, got them about a week later, and started putting the parts together. The pieces fit in snugly, so glue is not entirely necessary. Here is a picture of the wrist attached to the Velo2G before glue.
Here is an online link to our August 2013 SERVO Magazine article about our updates to PR2Lite.
We have an earlier article about PRLite in the December 2011 article of SERVO Magazine. Here is a link to that as well.
August 2013 SERVO Article
December 2011 SERVO Article