explanation the results

hello
i did the design in the next video
http://www.youtube.com/watch?v=yFw61xQpkvY&feature=youtu.be

i applied motor with the shown motion profile
https://www.dropbox.com/s/fkowpqu74tv672p/data%20point.jpg

to rotate the wheelchair as shown in the video

i got this torque

https://www.dropbox.com/s/1xzbanch3olta6u/torque.jpg


how can i show that theoritically or how solidworks find the motor torque ????
thanks

SolidworksMotion Studies