Rotary follower platform: how to implement?

Question

Sensors

There is a task: to make a certain turntable that will automatically turn a certain side towards the sensor. The distance from the platform to the sensor is no more than 50 meters. Angle of rotation 90-100 degrees (between extreme positions).
To begin with, he is interested in how the electronic part is: how to implement this in general, or in which direction to dig.
But I will not refuse advice on the mechanical part in two versions: 1. prototype, without load; 2. working sample - the weight of the cargo on the platform is up to 50 kg.