Im trying to build a weird idea for academic purpose. Trying to control a real car using joystick. So for the steering purpose and accelerator pedal, without modifying any internal mechanics, what Im trying to do is to attach a custom device to accelerator pedal and steering column so that it will physically pushes the accelerator using that motorized attachment.

So here are my concerns. With my very little knowledge in motor and these mechanical areas, Im really got confused which is the best motor which serves the purpose. Servo or Stepper. I dont know about these Nema rating as well. So with some theories does Nema 17 does serve the purpose?

Also for both steering and accelerator we should have to hold the positions in some state for some time. So as on considering all these factors Im requesting a good suggestion

  • 1
    \$\begingroup\$ use a servo for the accelerator pedal. you may be able to find one that is strong enough to press the pedal with its arm (sailboat servo may do the job), otherwise build a cam arrangement to press the pedal .... the steering needs a multi-turn actuator, so a stepping motor is probably the best for that \$\endgroup\$
    – jsotola
    May 10, 2018 at 4:23
  • \$\begingroup\$ And this has been done for quadriplegics over 30 years ago I suggest you do some homework and research how are you going to control modern cars use electronic Speed control and braking as done my Mercedes then how much power for steering and braking and safety measures are required for all features and then write a specification to define all input and output variables before you even consider the best method of conversion and control. \$\endgroup\$ May 10, 2018 at 4:51
  • \$\begingroup\$ @TonyStewartolderthandirt This is just for a demo purpose in a closed environment. After evaluation nothing more into it. Just to move and steer the car in an accurate way. Driver will be in car in case if it out of control. \$\endgroup\$ May 10, 2018 at 5:03
  • \$\begingroup\$ @jsotola Sorry.. out of a curiosity, why you suggested servo for the accelerator part. \$\endgroup\$ May 10, 2018 at 5:06
  • \$\begingroup\$ servo subsystems are plentiful and smaller as found in automotive and hobby market with a spring. But for steering which will have more torque , motor or human arms? or do you have to press a kill switch Do you understand Newtons of force? or torque, where is your spec? if not why suggest NEMA size \$\endgroup\$ May 10, 2018 at 10:58

1 Answer 1


I'd strongly suggest you do not use either RC servos or stepper motors.

Buy a Throttle servo designed for a car (many are drive by wire these days), or a cruise control servo. These automatically lose drive if anything goes wrong, or when you stop signaling them. There are plenty on Ebay or Amazon, just search for 'Cruise control servo'

Think of the safety requirements, you cannot afford for any fault to keep the throttle at a wrong setting.

  • \$\begingroup\$ Thats a great piece of information! So a throttle servo will work well for Acceleration and Steering, isnt it. \$\endgroup\$ May 10, 2018 at 11:29
  • \$\begingroup\$ It won't work for steering, it simply does not have enough torque. I'd suggest you will need to either provide a CAN bus entry on a modern vehicle, or build a DC motor driven servo for the application. \$\endgroup\$ May 10, 2018 at 17:32

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