Sc mc python examples

special command sequences that are interesting

Below are some special command that result in some interesting robot behavior. These special commands can be provided via 'do_command.py', or 'pfcmdmenu.exe', or directly in python with the method 'do_command' in the module 'pfcmd.py'.

The special command sequences below are listed in braces as comma separated values. For example for the sequence [100, 200, 300]

With do_command.py you would type: do_command.py -p <serial port> -s 100 200 300

With pfcmdmenu.exe, in the string box : 100 200 300

With python, assuming pf is an instance of pfcmd.py: result = pf.do_command('special', [100, 200, 300])

read robot status

• [104] # read SC status info
• [1101] # get motor mode
• [1106] # get encoder positions
• [1420] # get MC SM state
• [1105] # get motor velocity
• [1116] # read MC ADCs
• [1120] # get overload status values
• [230] # get IMU enable

prepare the hardware

Take the robot out of its boot mode so that it can be controlled externally. Generally the following special commands achieve this:

• [231, 0] # IMU off - to minimize possible loss of commands over the FUP
• [173,77,7] # demux statemachine to idle mode
• [170,77,17] # primary statemachine to the 'do nothing state'
• [1421, 17] # MC statemachine to a 'do nothing success state'

move robot back - fort in voltage mode

After preparing the hardware above, can use special command 1115 to command a fixed voltage across the motor:

• [1115, 1000, 0, 6] # qVq = 1000, mode = 6 (voltage
• sleep 1 sec
• [1115, -1000, 0, 6] # qVq=-1000
• sleep 1 sec
• [1115, 0,0,0] # short the motor leads

enter trajectory mode

The trajectory mode will servo the robot to the goal position. This is achieved by adjusting the sent point of a virtual spring (whos parmeters) are adjusted. The goal point for the VS is set based on diffeence equstion that produces an exponential response to a position step input.

• [1318, 100] # set goal position to 100 need to be careful to limit the goal position to valid positions!!!
• [1421, 41] # go to trajectory control mode, robot immediatly jumps!
• sleep 1 sec
• [1318, 500] # servo to position 500