A similar approach can be applied to the dips exercise. Provide assistance with a boost from the ground, or perform the exercise without assistance.
1) Chin-ups are one of the best exercises to build shoulder strength and the biceps.
2) The bars can be set at a heigth that allows a boost from the ground which applies momentum to the pull.
If You have medical condition which might need special attention then seek medical or experts advice. Protection from adult is required when children and elder are using it.