Choosing the right gear system and motor for Robotics project

Hello all. I am currently attempting to design a robotic system that will allow disabled children to crawl. At the moment I am trying to choose the appropriate actuators for my project. I have a max torque requirement from the system of around 60n/m. I need the motor to have a brake that doesn’t require electrical power and a way of measuring the angular position of my actuator. For the project the actuator doesn’t need to run continuously, the actuator only needs a range of around 0-180 degrees. So far, the best idea I have come up with is a high ratio planetary gearbox with a worm gear to prevent back drivability without power. A potentiometer is likely to be used to measure angular position. I was just wondering, as I am quite new to the world of robotics, what would be the next step in designing my gear system, or is there a solution I have not come across yet? Am I missing anything important I need to know. I have attached pictures to try and highlight my question. I am currently only concerning the top leg actuators.

Thanks in advance,
Peter Wright

@PeterWright93 Welcome to the RobotShop Community.

If the requirement is that the braking effect doesn’t require power, then yes, a worm gear seems best. The alternative would be an electromagnetic brake which is normally ON, so when power is applied, the brake is OFF so the actuator can rotate. Alternatively, since I cannot quite tell what the motion is, there might be the possibility of using a linear actuator, which is also self-locking.

The closest such worm gear motors RobotShop sells can be found here: