Human power amplifier for lifting load with slack prevention apparatus

A method of improving the responsiveness of a hoist that includes an end-effector held by an operator and connected to a load to be lifted, a sensor in the end-effector that measures operator-applied force and sends a signal representing operator-applied force to a controller, and a hoist actuator varying speed of movement of a line transmitting tensile force from the actuator to the end-effector to assist the operator in lifting the load, the method comprising:

• a. estimating load force with a load force estimator;
• b. transmitting a load force signal from the load force estimator to the controller;
• and
• c. programming the controller to control actuator speed as a function of the load force signal and the operator-applied force signal.

A system for improving hoist responsiveness to operator input, wherein the hoist includes an end-effector held by an operator and connectable to a load to be lifted, a sensor in the end-effector detecting operator-imposed force during lifting and sending to a controller a signal representing operator-imposed force, a hoist actuator having an operating speed set by the controller, and a line transmitting tensile force between the actuator and the end-effector to assist the operator in lifting the load, the system comprising:

• a. a load force estimator that determines a force on the line caused by a load being lifted;
• b. the load force estimator sending a load force signal to the controller;
• and
• c. the controller varying lifting speed in response to the operator-imposed force as a function of the load force signal.

A hoist system giving an operator a realistic sense of a lifting task that the operator indicates by operator-applied force to an end-effector connected to a load and connected to a hoist by a line, a signal representing operator-applied force during the lifting task being implemented by a controller, operating an actuator connected to the end-effector by the line, the system comprising:

• a. a load force measurer supplying a load force signal to the controller;
• b. the controller operating the actuator to implement an operator-indicated lifting task variably in response to the load force signal and the operator-applied force signal;
• and
• c. the controller being programmed so that the operator must exert a greater operator-applied force for a heavier load than is required to raise a lighter load at the same speed.

A hoist system controlling load lifting speed responsively to operator input, the hoist system comprising:

• a. a controller receiving signals representing load force and operator-applied force;
• b. the controller being programmed to control lifting speed as a function of both signals;
• and
• c. the controller being further programmed so that a change in load weight increases and a change in operator-applied force cause a change in load speed according to the equation:
• (1+SE+GQE)Δv=(GK+S)Δf+(S+GQ)(ΔW)
• where S represents an actuator sensitivity transfer function, E represents load dynamics, G represents an actuator transfer function, Q represents a controller transfer function operating on p, Δv represents change in end-effector velocity, Δf represents change in operator-applied force, K represents a transfer function of the controller operating on f and ΔW represents change in load weight.

A method of preventing a hoist line from becoming slack, the method comprising:

• a. detecting absence of tensile force in the line;
• b. signaling a controller of an actuator of the hoist whenever the line tensile force is absent;
• and
• c. programming the controller to prevent the actuator from unreeling line in response to operator input of downward movement whenever line tensile force is absent.