The tank guns I was planning on using on my mech Gold Rush were just not cutting it for me. Problems included gear skipping and motors burning up. So I was forced to ditch them and went for something a bit bigger.
I have temporarily mounted all of Gold Rush’s electronics to the top of his chassis so I could start testing his walking.
Over the last week I have been able to get wireless control working with my AVR micro. Communication to the AVR is being done by sending wireless serial data packets using xbee modules.
At the moment my packets consist of two header bytes (0xff) to designate the start of a new packet. The header is then followed with 4 bytes to hold the values of 2 joystick (horizontal and vertical axis). The packet is then ended with a checksum.
I have created a simple python and wxpython app to simulate the control of two joysticks using some slider widgets. This app simply reads the value of the 4 sliders, forms a data packet and writes it out serially to a xbee module connected to my PC around 30 times a second.
On the micro side I have a second xbee module connected to one of the atmega644′s usarts. The micro is adding every byte it receives on this usart to a ring buffer. Then, when called, a function is able to search this buffer for a full data packet, pull out the joystick data and flush the buffer.
Here is a little video I took to demonstrate it all working. Off camera I am changing the values on the top two sliders in my python app. These two sliders represent the vertical and horizontal axis of a single joystick. In turn the value of each slider determines the walking direction of the robot.
Progress continues with my AVR microcontroller board…
Today I was able to get some simple wireless serial communication tests working.
I followed this great tutorial post on AVR Freaks on creating interrupt driven USART echo program. I then took it a step farther and had each side of the serial link (PC and micro) echo the last character received pulse one.
All in all the test were not very interesting but they do lay groundwork for the development of a control packet structure for driving Gold Rush around.
I got to work on Gold Rush and completely replaced all the stock bioloid brackets used for the legs. All parts were machined from 0.06 inch thick aluminum sheet on a manual vertical mill, bent with a metal brake and media blasted.
I have uploaded two videos of walking gaits that I have been working on for Gold Rush.
First up is a video of an eight step ripple gait:
This video showcases an amble gait as well as a feature that allows the robot change walking gaits on the fly: